|Abstracts on Global Climate Change|
Modelling and measuring the spectral bidirectional reflectance factor of snow-covered sea ice: an intercomparison study
Li, SS Zhou, XB
HYDROLOGICAL PROCESSES 18:18 3559-3581
Broadband albedo is a very important geophysical parameter in the Earth surface-atmosphere interaction in either global climate change or hydrological cycle and snowmelt runoff studies. To derive the broadband albedo accurately from satellite optical sensor observation at limited bands and at a single observation angle, the bidirectional reflectance factor (BRF) has to be specified quantitatively. In the present albedo derivation algorithms from the satellite radiance data, the BRF is either modelled or observed. Questions may arise as to how well a BRF model can be in the broadband albedo derivation. To help answer such questions, we studied the performance of a snow-surface BRF model for two specific cases under large solar zenith angles (65degrees and 85degrees). We measured snow-surface spectral directional reflectance under clear skies. The snow physical properties, such as snow grain size and snow density, at the same sites were also measured. In situ snow physical data are used to simulate the snow-surface BRF and hemispherical directional reflectance factor (HDRF) through a multilayered azimuth- and zenith-dependent plane-parallel radiative transfer model. The field measurements and BRF and HDRF simulations all reveal the forward-scattering nature of snow surface under large solar incidence angles, but the BRF model results depict the strongest forward-scattering patterns under such solar zenith angles. Because the HDRF is simulated through coupling of the surface BRF with radiative transfer in the atmosphere, the resulting HDRF patterns agree with the field measurements better than the simulated BRF does. The deviation of the simulated HDRF from field-based clear-sky directional reflectance (FCDR) is within +/- 10% for the central (viewing zenith angle <45degrees) and lateral sides of the viewing hemisphere. This level of agreement between the simulated HDRF and FCDR also implies that the simulated BRF model can provide remote-sensing estimates of spectral albedo with an uncertainty of +/- 10% for the same part of the viewing hemisphere. Further improvement in BRF model performance requires better handling of single scattering properties of snow grains, surface roughness, and atmospheric correction. Also, better procedures and techniques in field measurement are necessary for more accurate assessment of the performance of BRF models. Copyright (C) 2004 John Wiley Sons, Ltd.
Paleoclimate and faunal evolution in the Plio-Pleistocene of Africa and South America
Quinteros, RB Behrensmeyer, AK Ormazabal, GC
AMEGHINIANA 41:4 641-649
PALEOCLIMATE AND FAUNAL EVOLUTION IN THE PLIO-PLEISTOCENE OF AFRICA AND SOUTH AMERICA. Climatic change is often hypothesized to be a major variable in forcing evolutionary change. Recent work on Pliocene and Pleistocene fossil mammals from the Turkana Basin of Kenya and Ethiopia shows that climate may play an important role in the spread of savanna environments, and thus in the increasing abundance of mammals adapted to open and seasonally and conditions. If global climate change is behind some of these trends in East Africa, we hypothesize that similar patterns of faunal change may occur elsewhere. An analysis of fossil mammals from the Pampean region of Argentina shows an increase in the number of species adapted to open and seasonally and conditions through the Plio-Pleistocene. The South American pattern is not identical to the East African pattern, but both show a significant increase in open and and adapted mammals shortly after 2 million years ago, at the very beginning of the Pleistocene. Although global climate change may be invoked as a common cause of these intercontinental trends, local and regional geography and tectonics play a critical role in modulating the global signal.
Geographical potential of Argentine ants (Linepithema humile Mayr) in the face of global climate change
Roura-Pascual, N Suarez, AV Gomez, C Pons, P Touyama, Y Wild, AL Peterson, AT
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES 271:1557 2527-2534
Determining the spread and potential geographical distribution of invasive species is integral to making invasion biology a predictive science. We assembled a dataset of over 1000 occurrences of the Argentine ant (Linepithema humile), one of the world’s worst invasive alien species. Native to central South America, Argentine ants are now found in many Mediterranean and subtropical climates around the world. We used this dataset to assess the species’ potential geographical and ecological distribution, and to examine changes in its distributional potential associated with global climate change, using techniques for ecological niche modelling. Models developed were highly predictive of the species’ overall range, including both the native distributional area and invaded areas worldwide. Despite its already widespread occurrence, L. humile has potential for further spread, with tropical coastal Africa and southeast Asia apparently vulnerable to invasion. Projecting ecological niche models onto four general circulation model scenarios of future (2050s) climates provided scenarios of the species’ potential for distributional expansion with warming climates: generally, the species was predicted to retract its range in tropical regions, but to expand at higher latitude areas.
The impact of surface-adsorbed phosphorus on phytoplankton Redfield stoichiometry
Sanudo-Wilhelmy, SA Tovar-Sanchez, A Fu, FX Capone, DG Carpenter, EJ Hutchins, DA
NATURE 432:7019 897-901
The Redfield ratio of 106 carbon: 16 nitrogen: 1 phosphorus in marine phytoplankton(1) is one of the foundations of ocean biogeochemistry, with applications in algal physiology(2), palaeoclimatology(3) and global climate change(4). However, this ratio varies substantially in response to changes in algal nutrient status(5) and taxonomic affiliation(6,7). Here we report that Redfield ratios are also strongly affected by partitioning into surface-adsorbed and intracellular phosphorus pools. The C: N: surface-adsorbed P (80 - 105 C: 15 - 18 N: 1 P) and total (71 - 80 C: 13 - 14 N: 1 P) ratios in natural populations and cultures of Trichodesmium were close to Redfield values and not significantly different from each other. In contrast, intracellular ratios consistently exceeded the Redfield ratio ( 316 - 434 C: 59 - 83 N: 1 intracellular P). These high intracellular ratios were associated with reduced N-2 fixation rates, suggestive of phosphorus deficiency. Other algal species also have substantial surface-adsorbed phosphorus pools, suggesting that our Trichodesmium results are generally applicable to all phytoplankton. Measurements of the distinct phytoplankton phosphorus pools may be required to assess nutrient limitation accurately from elemental composition. Deviations from Redfield stoichiometry may be attributable to surface adsorption of phosphorus rather than to biological processes, and this scavenging could affect the interpretation of marine nutrient inventories and ecosystem models.
Initial public perceptions of deep geological and oceanic disposal of carbon dioxide
Palmgren, CR Morgan, MG De Bruin, WB Keith, DW
ENVIRONMENTAL SCIENCE & TECHNOLOGY 38:24 6441-6450
Two studies were conducted to gauge likely public perceptions of proposals to avoid releasing carbon dioxide from power plants to the atmosphere by injecting it into deep geological formations or the deep ocean. Following a modified version of the mental model interview method, Study 1 involved face-to-face interviews with 18 nontechnical respondents. Respondents shared their beliefs after receiving basic information about the technologies and again after getting specific details. Many interviewees wanted to frame the issue in the broader context of alternative strategies for carbon management, but public understanding of mitigation strategies is limited. The second study, administered to a sample of 126 individuals, involved a closed-form survey that measured the prevalence of general beliefs revealed in study 1 and also assessed the respondent’s views of these technologies. Study results suggest that the public may develop misgivings about deep injection of carbon dioxide because it can be seen as temporizing and perhaps creating future problems. Ocean injection was seen as more problematic than geological injection. An approach to public communication and regulation that is open and respectful of public concerns is likely to be a prerequisite to the successful adoption of this technology.
Evolution of late glacial ice-marginal lakes on the northwestern Canadian Shield and their influence on the location of the Dubawnt Lake palaeo-ice stream
Stokes, CR Clark, CD
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 215:1-2 155-171
During deglaciation of the North American Laurentide Ice Sheet large proglacial lakes developed in positions where proglacial drainage was impeded by the ice margin. For some of these lakes, it is known that subsequent drainage had an abrupt and widespread impact on North Atlantic Ocean circulation and climate, but less is known about the impact that the lakes exerted on ice sheet dynamics. This paper reports palaeogeographic reconstructions of the evolution of proglacial lakes during deglaciation across the northwestern Canadian Shield, covering an area in excess of 1,000,000 km(2) as the ice sheet retreated some 600 km. The interactions between proglacial lakes and ice sheet flow are explored, with a particular emphasis on whether the disposition of lakes may have influenced the location of the Dubawnt Lake ice stream. This ice stream falls outside the existing paradigm for ice streams in the Laurentide Ice Sheet because it did not operate over fined-grained till or lie in a topographic trough. Ice margin positions and a digital elevation model are utilised to predict the geometry and depth of proglacial takes impounded at the margin at 30-km increments during deglaciation. Palaeogeographic reconstructions match well with previous independent estimates of lake coverage inferred from field evidence, and results suggest that the development of a deep lake in the Thelon drainage basin may have been influential in initiating the ice stream by inducing calving, drawing down ice and triggering fast ice flow. This is the only location alongside this sector of the ice sheet where large (>3000 km(2)), deep lakes (similar to120 m) are impounded for a significant length of time and exactly matches the location of the ice stream. It is speculated that the commencement of calving at the ice sheet margin may have taken the system beyond a threshold and was sufficient to trigger rapid motion but that once initiated, calving processes and losses were insignificant to the functioning of the ice stream. It is thus concluded that proglacial lakes are likely to have been an important control on ice sheet dynamics during deglaciation of the Laurentide Ice Sheet. (C) 2004 Elsevier B.V. All rights reserved.
RNA/DNA ratios as indicators of metabolic activity in four species of Caribbean reef-building corals
Buckley, BA Szmant, AM
MARINE ECOLOGY-PROGRESS SERIES 282: 143-149
Global climate change and the anthropogenic degradation of tropical reef environments can have deleterious consequences for the health of reef-building corals. Bioindicators of coral status aid in efforts to identify those species and populations that are most threatened, which can help focus conservation efforts. The RNA/DNA ratio is an index of protein synthetic capacity and is expected to reflect an organism’s investment in growth. Here, we measured a decrease in the RNA/DNA ratio in both the symbiotic anemone Aiptasia pallida exposed to light-deprivation in the laboratory, and in natural populations of the coral Porites astreoides along a depth gradient, suggesting that the RNA/DNA ratio may have depended upon metabolic activity. Also, RNA/DNA ratios in the coral Montastraea annularis were higher in the winter and spring (when higher growth rates may have been supported) than in summer, at an inshore and an offshore reef in the Florida Keys. Site-specific disparity in bleaching patterns at these 2 reefs may partly explain the differences in their RNA/DNA ratios. Finally, significant interspecific variation was observed in 3 co-occurring species of the genus Montastraea: M. annularis, M. cavernosa and M, faveolata, demonstrating the potential for variability in protein synthetic capacity even between closely related species. These results support the use of the RNA/DNA ratio as an indicator of metabolic activity in natural populations of corals.
The influence of the global climate change on the forest ecosystems in the low tatras Mts
Balaz, P Mindas, J
EKOLOGIA-BRATISLAVA 23: Suppl. 2 1-12
The paper presents the results of possible regional effects of global climate change on the tree species composition of mountain forest ecosystems. Our model area has been represented by the valleys: Vajskova and Lomnista in Low Tatras Mts region. The suitability of the current and future changed climatic conditions for particular species has been assessed by means of the analysis of the bioclimatic area of each examined tree species. The analysis has been done for the tree species as follows: Norway spruce (Picea abies), silver fir (Abies alba), European beech (Fagus sylvatica), mountain pine (Pinus mugo), sycamore maple (Acer pseudoplatanus), European ash (Fraxinus excelsior), European larch (Larix decidua), mountain ash (Sorbus aucuparia) and cembra pine (Pinus cembra). The results hint at the possibility of considerable changes in the tree composition of mountain forests in the future. The climatic changes will probably have a negative impact primarily on silver fir, Norway spruce and mountain pine - important commercial and stand building species, The effects of the climatic changes are also expected on other species.
Will OPEC lose from the Kyoto Protocol?
Barnett, J Dessai, S Webber, M
ENERGY POLICY 32:18 2077-2088
A range of energy-economy models forecast losses to members of the Organisation of Petroleum Exporting Countries (OPEC) should the Kyoto Protocol come into force. These forecasts are a powerful influence in the United Nations Framework Convention on Climate Change negotiations. They are used by OPEC to advance the agenda on the impacts of response measures, covertly arguing for compensation for lost oil revenues arising from implementation of the Protocol. This paper discusses this issue, and explores the key assumptions of these models and their uncertainties. Assumptions about carbon leakage, future availability of oil reserves, substitution, innovation, and capital turnover are considered. The paper suggests that losses will not affect OPEC countries equally, and that these losses are not likely to be as substantial as the models forecast. A range of policy measures are proposed to lessen any impact the Protocol may have on OPEC. (C) 2003 Elsevier Ltd. All rights reserved.
Declining extent of open-water refugia for top predators in Baffin Bay and adjacent waters
Heide-Jorgensen, MP Laidre, K
AMBIO 33:8 487-494
Global climate change is expected to severely impact Arctic ecosystems, yet predictions of impacts are complicated by region-specific patterns and nonuniform trends. Twentyfour open-water overwintering areas (or “microhabitats”) were identified to be of particular importance for eight seabird and marine mammal species in the eastern Canadian High Arctic and Baffin Bay. Localized trends in the available fraction of open-water were examined in March during 1979-2001, derived from approximate sea ice concentrations from satellite-based microwave telemetry. Declines in the fraction of open-water were identified at microhabitats in Baffin Bay, Davis Strait, coastal West Greenland, and Lancaster Sound. Increases in open-water were observed in Hudson Bay, Hudson Strait, and Foxe Basin. The biological importance of each microhabitat was examined based on species distribution and abundance. Potential consequences of reduced open-water for top marine predators include impacts on foraging efficiency and oxygen and prey availability.
Are climate change impacts already affecting tropical forest biomass?
GLOBAL ENVIRONMENTAL CHANGE-HUMAN AND POLICY DIMENSIONS 14:4 299-302
Tropical forests contain large stocks of carbon and any change in the balance of inflows and outflows of carbon to the biomass of standing forest has potentially important consequences for the global carbon cycle and related greenhouse warming, as well as for tropical biodiversity. Despite unresolved controversies over observed changes in biomass and gas fluxes, current observations indicate the likelihood that additional climate change would have substantial impacts on tropical forests and would reinforce their contributions to global climate change. Climate change impacts are already affecting tropical forest biomass. (C) 2004 Elsevier Ltd. All rights reserved.
New evidence for a volcanically, tectonically, and climatically active Mars
Marquez, A Fernandez, C Anguita, F Farelo, A Anguita, J de la Casa, MA
ICARUS 172:2 573-581
Geological analysis of Mars imagery supports the hypothesis that the planet has been the site of recent (< 10 Ma) volcanic and tectonic processes and glacier flow, and makes most likely previous suggestions of continuing endogenic and exogenic activity. Tectonic structures which deform very slightly cratered (at MOC scales) surfaces of Tharsis Montes and surrounding regions Seem to attest to active tectonism (both extensional and transcurrent) on Mars. Exogenic processes in this region, such as a glacial origin for the aureole deposits on the northwestern flanks of the Tharsis Montes shield volcanoes, are supported by new data. The very recent age of these structures could be the first direct confirmation that drastic changes in obliquity are modulating the martian climate, such that an increase in obliquity would result in equatorial glaciers taking the place of the receding polar ice caps. If this and other concurring research is extended and confirmed. the ‘alive Mars’ Which would emerge would constitute a most appealing place for exobiology and comparative planetology. (C) 2004 Elsevier Inc. All rights reserved.
Impact analysis of climate change for an Alpine catchment using high resolution dynamic downscaling of ECHAM4 time slices
Kunstmann, H Schneider, K Forkel, R Knoche, R
HYDROLOGY AND EARTH SYSTEM SCIENCES 8:6 1030-1044
Global climate change affects spatial and temporal patterns of precipitation and so has a major impact on surface and subsurface water balances. While global climate models are designed to describe climate change on global or continental scales, their resolution is too coarse for them to he suitable for describing regional climate change. Therefore, regional climate models are applied to downscale the coarse meteorological fields to a much higher spatial resolution to take account of regional climate phenomena. The changes of atmospheric state due to regional climate change must be translated into surface and sub-surface water fluxes so that the impact on water balances in specific catchments can be investigated. This can be achieved by the coupled regional climatic/hydrological simulations presented here. The non-hydrostatic regional climate model MCCM was used for dynamic downscaling for two time slices of a global climate model Simulation with the GCM ECHAM4 (IPCC scenario IS92a, ‘business as usual) from 2.8 degrees x 2.8 degrees to 4 x 4 km(2) resolution for the years 1991-1999 and 203 1-2039. This allowed derivation of detailed maps showing changes in precipitation and temperature in a region of southern Germany and the central Alps. The performance of the downscaled ECHAM4 to reproduce the seasonality of precipitation in central Europe for the recent climate was investigated by comparison with dynamically downscaled ECMWF reanalyses in 20 x 20 km2 resolution. The downscaled ECHAM4 Fields underestimate precipitation significantly in summer. The ratio of mean monthly downscaled ECHAM4 and ECMWF, precipitation showed little variation. so it was used to adjust the course of precipitation for the ECHAM4/MCCM fields before it was applied in the hydrological model. The high resolution meteorological fields were aggregated to 8-hour time steps and applied to the distributed hydrological model WaSiM to simulate the water balance of the alpine catchment of the river Ammer (c. 700 km(2)) at 100 x 100 m(2) resolution. To check the reliability of the Coupled regional climatic/hydrological simulation results for the recent climate, they were compared with those of a station-based hydrological simulation for the period 1991-1999. This study shows the changes in the temperature and precipitation distributions in the catchment from the recent climate to the future climate scenario and how these will affect the frequency distribution of runoff.
Solving the climate problem - Technologies available to curb CO2 emissions
Socolow, R Hotinski, R Greenblatt, JB Pacala, S
ENVIRONMENT 46:10 8-19
In an effort to avoid serious ecological disruption and global climate change,low-carbon energy strategies need to be implemented on a world-wide scale along with the introduction of carbon policies and carbon management.
Long-term changes in migration timing of adult Atlantic salmon (Salmo salar) at the southern edge of the species distribution
Juanes, F Gephard, S Beland, K
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES 61:12 2392-2400
The Connecticut River historically represented the southernmost extent of the North American range of Atlantic salmon (Salmo salar), but the native population was extirpated 200 years ago by dam construction. An extensive restoration effort has relied upon stock transfers from more northerly rivers, especially the Penobscot River (Maine). Recent work has shown differences in age structure between donor and derivative populations. Here we focus on a related life-history trait, the timing of the adult migration. We examined 23 years of migration timing data collected at two capture locations in the Connecticut River drainage. We found that both dates of first capture and median capture dates have shifted significantly earlier by about 0.5 days(.)year(-1). To conclude whether this is a consequence of local adaptation or a coast-wide effect, we also quantified changes in migration timing of more northerly stocks (in Maine and Canada). We found that the changes in migration timing were not unique to the Connecticut River stock and instead observed coherent patterns in the shift towards earlier peak migration dates across systems. These consistent shifts are correlated with long-term changes in temperature and flow and may represent a response to global climate change.
The Earth Simulator: roles and impacts
PARALLEL COMPUTING 30:12 1279-1286
The Earth Simulator Research Project started in March 2002 with the primary objective of producing reliable prediction data for global climate change. Within a couple of months after the start of operation, the Earth Simulator achieved an amazing performance of 35.86 Teraflops (about 90% of the peak performance of 40.96 Teraflops) in the Linpack benchmark test and, more surprisingly, 26.58 Teraflops for a typical application program of global atmospheric circulation model (called AFES) with a horizontal resolution of 10km. These facts ensure us that the real contribution of the Earth Simulator be far greater than originally expected. Undoubtedly, the Earth Simulator would work to make a paradigm shift in science, industry, and human thinking, as well as finding the best human’s wisdom to keep a sustainable symbiotic relationship with nature. (C) 2004 Elsevier B.V. All rights reserved.
Changes in lagoonal marsh morphology at selected northeastern Atlantic coast sites of significance to migratory waterbirds
Erwin, RM Sanders, GM Prosser, DJ
WETLANDS 24:4 891-903
Five lagoonal salt marsh areas, ranging from 220 ha to 3,670 ha, were selected from Cape Cod, Massachusetts to the southern DelMarVa peninsula, Virginia, USA to examine the degree to which Spartina marsh area and microhabitats had changed from the early or mid- 1900s to recent periods. We chose areas based on their importance to migratory bird populations, agency concerns about marsh loss and sea-level rise, and availability of historic imagery. We georeferenced and processed aerial photographs from a variety of sources ranging from 1932 to 1994. Of particular interest were changes in total salt marsh area, tidal creeks, tidal flats, tidal and non-tidal ponds, and open water habitats. Nauset Marsh, within Cape Cod National Seashore, experienced an annual marsh loss of 0.40% (19% from 1947 to 1994) with most loss attributed to sand overwash and conversion to open water. At Forsythe National Wildlife Refuge in southern New Jersey, annual loss was 0.27% (17% from 1932 to 1995), with nearly equal attribution of loss to open water and tidal pond expansion. At Curlew Bay, Virginia, annual loss was 0.20% (9% from 1949 to 1994) and almost entirely due to perimeter erosion to open water. At Gull Marsh, Virginia, a site chosen because of known erosional losses, we recorded the highest annual loss rate, 0.67% per annum, again almost entirely due to erosional, perimeter loss. In contrast, at the southernmost site, Mockhorn Island Wildlife Management Area, Virginia, there was a net gain of 0.09% per annum (4% from 1949 to 1994), with tidal flats becoming increasingly vegetated. Habitat. implications for waterbirds are considerable; salt marsh specialists such as laughing gulls (Larus atricilla), Forster’s terns (Sterna forsteri), black rail, (Laterallus jamaicensis), seaside sparrow (Ammodramus maritimus), and saltmarsh sharp-tailed sparrow (Ammodramus caudacutus) are particularly at risk if these trends continue, and all but the laughing gull are species of concern to state and federal managers.
Mineral stress: the missing link in understanding how global climate change will affect plants in real world soils
Lynch, JP St Clair, SB
FIELD CROPS RESEARCH 90:1 101-115
Many natural and agricultural ecosystems are characterized by sub-optimal availability of mineral nutrients and ion toxicities. Mineral stresses are likely to have important, complex, and poorly understood interactions with global climate change variables. For example, most terrestrial vegetation is supported by weathered soils with some combination of low P, low Ca, Al toxicity, and Mn toxicity. Each of these stresses has complex, yet distinct, interactions with global change variables, making it very difficult to predict how plants in these environments will respond to future climate scenarios. Important, yet poorly understood, interactions include the effects of transpiration on root acquisition of soluble nutrients, particularly Ca and Si, the effects of altered root architecture on the acquisition of immobile nutrients, particularly P, the effects of altered root exudate production on Al toxicity and transition metal acquisition, and the interaction of photochemical processes with transition metal availability. The interaction of Mn toxicity with light intensity and other global change variables is discussed as an example of the complexity and potential importance of these relationships. Current conceptual models of plant response to multiple resource limitations are inadequate. Furthermore, substantial genetic variation exists in plant responses to mineral stress, and traits improving adaptation to one stress may incur tradeoffs for adaptation to other stresses. Root traits under quantitative genetic control are of central importance in adaptation to many mineral stresses. An integration of quantitative genetics with mechanistic and conceptual models of plant response to mineral stresses is needed if we are to understand plant response to global change in real-world soils. (C) 2004 Elsevier B.V. All rights reserved.
Genomics and the physiologist: bridging the gap between genes and crop response
Edmeades, GO McMaster, GS White, JW Campos, H
FIELD CROPS RESEARCH 90:1 5-18
Plant physiologists have traditionally studied the relationship between crop performance (the phenotype) and the environment. Global change processes present multiple challenges to crop performance that can be met effectively by changing the crop environment through management, and by modifying the crop genome (the genotype) through plant breeding and molecular biology. In order to increase the reliability of crop performance prediction based upon genetic information, new tools are needed to more effectively relate observed phenotypes to genotypes. The emerging discipline of genomics offers promise of providing such tools, and may provide a unique opportunity to enhance genetic gains and stabilize global crop production. Genomics has developed from the confluence of genetics, automated laboratory tools for generating DNA- and RNA-based data, and methods of information management. Functional genomics concentrates on how genes function, alone and in networks, while structural genomics focuses on physical and structural aspects of the genome. The traditional strengths of physiology lie in interpreting whole plant response to environmental signals, dissecting traits into component processes, and predicting correlated responses when genes and pathways are perturbed. These complement information on the genetic control of signal transduction, gene expression, gene networks and candidate genes. Combining physiological and genetic information can provide a more complete model of gene-to-phenotype relationships and genotype-by-environment interactions. Phenotypic screening procedures that more accurately identify underlying genetic variation, and crop models that incorporate Mendelian genetic controls of key processes provide two tangible examples of fruitful collaboration between physiologists and geneticists. These point to a productive complementary relationship between disciplines that will speed progress towards stable and adequate food production, despite challenges posed by global climate change. (C) 2004 Published by Elsevier B.V.
Improving drought tolerance in maize: a view from industry
Campos, H Cooper, A Habben, JE Edmeades, GO Schussler, JR
FIELD CROPS RESEARCH 90:1 19-34
Significant yield losses in maize (Zea mays L.) from drought are expected to increase with global climate change as temperatures rise and rainfall distribution changes in key traditional production areas. The success of conventional crop improvement over the past 50 years for drought tolerance forms a baseline against which new genetic methods must be compared. Selection based on performance in multi-environment trials (MET) has increased grain yield under drought through increased yield potential and kernel set, rapid silk exertion, and reduced barrenness, though at a lower rate than under optimal conditions. Knowledge of the physiology of drought tolerance has been used to dissect the trait into a series of key processes. This has been complemented by genetic dissection through the identification of QTL associated with these same traits. Both have been used to identify suitable organ- and temporal-specific promoters and structural genes. Phenotyping capacity has not kept pace with the exponential increase in genotypic knowledge, and large-scale managed stress environments (MSE) are now considered essential to further progress. These environments provide ideal settings for conducting massively parallel transcript profiling studies, and for validating candidate regions and genes. Genetic and crop physiological models of key processes are now being used to confirm the value of traits for target environments, and to suggest efficient breeding strategies. Studies of gene to phenotype relationships suggest that most putative drought tolerance QTL identified thus far are likely to have limited utility for applied breeding because of their dependency on genetic background or their sensitivity to the environment, coupled with a general lack of understanding of the biophysical bases of these context dependencies. Furthermore, the sample of weather conditions encountered during progeny selection within the multi environment testing of conventional breeding programs can profoundly affect allele frequency in breeding populations and the stress tolerance of elite commercial products. We conclude that while gains in kernels per plant can be made by exploiting native genetic variation among elite breeding lines, improvements in functional stay-green or in root distribution and function may require additional genetic variation from outside the species. Genomic tools and the use of model plants are considered indispensable tools in this search for new ways of optimizing maize yield under stress. (C) 2004 Elsevier B.V. All rights reserved.
Dynamics of carbon sequestration in a coastal wetland using radiocarbon measurements
Choi, YH Wang, Y
GLOBAL BIOGEOCHEMICAL CYCLES 18:4 -
[ 1] Coastal wetlands are sensitive to global climate change and may play an important role in the global carbon cycle. However, the dynamics of carbon ( C) cycling in coastal wetlands and its response to sea level change associated with global warming is still poorly understood. In this study, we estimated the long-term and short-term rates of C accumulation, using C and C isotopic measurements of peat cores collected along a soil chronosequence, in a coastal wetland in north Florida. The long-term C accumulation rates determined by examining the C inventory and the radioactive decay of radiocarbon as a function of depth in the peat cores decrease with time from -130 +/- 9 g C/m(2)/yr over the last century to -13 +/- 2 g C/m(2)/yr over the millennium timescale. The short-term C accumulation rates estimated by examining the differences in the radiocarbon and C contents of the surfacial peat between archived ( 1985, 1988) and present ( 1996 and 1997) samples range from 42 to 193 g C/m(2)/yr in low marsh, from 18 to 184 g C/m(2)/yr in middle marsh, and from -50 to 181 g C/m(2)/yr in high marsh. The high end-values of our estimated short-term C accumulation rates are comparable to the estimated rates of C sequestration in coastal wetlands reported by Chmura et al. [ 2003], but are significantly higher than our estimated long-term rates in the marshes and are also much higher than the published rates of C sequestration in northern peatlands. The higher recent rates of C accumulation in coastal marshes, in comparison with the longer-term rates, are due to slow but continuous decomposition of organic matter in the peat over time. However, other factors such as increased primary production in the coastal wetland over the last decades or century, due to a rise in mean sea level and/or CO2 and nitrogen fertilization effect, could also have contributed to the large difference between the recent and longer-term rates. Our data indicate that salt marshes in this area have been and continue to be a sink for atmospheric carbon dioxide. Because of higher rates of C sequestration and lower CH4 emissions, coastal wetlands could be more valuable C sinks per unit area than other ecosystems in a warmer world.
Heat stress induces different forms of cell death in sea anemones and their endosymbiotic algae depending on temperature and duration
Dunn, SR Thomason, JC Le Tissier, MDA Bythell, JC
CELL DEATH AND DIFFERENTIATION 11:11 1213-1222
Bleaching of reef building corals and other symbiotic cnidarians due to the loss of their dinoflagellate algal symbionts (=zooxanthellae), and/or their photosynthetic pigments, is a common sign of environmental stress. Mass bleaching events are becoming an increasingly important cause of mortality and reef degradation on a global scale, linked by many to global climate change. However, the cellular mechanisms of stress-induced bleaching remain largely unresolved. In this study, the frequency of apoptosis-like and necrosis-like cell death was determined in the symbiotic sea anemone Aiptasia sp. using criteria that had previously been validated for this symbiosis as indicators of programmed cell death (PCD) and necrosis. Results indicate that PCD and necrosis occur simultaneously in both host tissues and zooxanthellae subject to environmentally relevant doses of heat stress. Frequency of PCD in the anemone endoderm increased within minutes of treatment. Peak rates of apoptosis-like cell death in the host were coincident with the timing of loss of zooxanthellae during bleaching. The proportion of apoptosis-like host cells subsequently declined while cell necrosis increased. In the zooxanthellae, both apoptosis-like and necrosis-like activity increased throughout the duration of the experiment (6 days), dependent on temperature dose. A stress-mediated PCD pathway is an important part of the thermal stress response in the sea anemone symbiosis and this study suggests that PCD may play different roles in different components of the symbiosis during bleaching.
Investigation of plasma irregularity sources associated with charged dust in the earth’s mesosphere
Scales, WA Ganguli, G
SCIENTIFIC EXPLORATION, PLANETARY PROTECTION, ACTIVE EXPERIMENTS AND DUSTY PLASMAS 34:11 2402-2408
Noctilucent clouds (NLCs) and polar mesospheric summer echoes (PMSEs) are two phenomena at the forefront of near earth space science. NLCs are high altitude clouds in the earth’s mesosphere that are formed from aerosol particles. The increase in the occurence of NLCs over time is believed to have profound implications on global climate change. PMSEs are believed to be related to NLCs and are strong radar echoes from mesospheric turbulence in the 50 MHz to 1.3 GHz range. Currently, there is no universally accepted explanation for the irregularities thought to produce PMSEs. Recent simultaneous sounding rocket, radar, and lidar observations of NLCs and PMSEs have provided a more detailed description of the electrodynamics and plasma configuration inside NLCs and the relationship to PMSEs. Particularly important is the simultaneous observation of charged aerosols, electron depletions, and small-scale electric field irregularities in the PMSE generation region. This work considers the consequences of the recent experimental observations on ultimately understanding the generation mechanism for PMSEs and the relationship to NLCs. A model for the electrodynamics and plasma configuration in the charged aerosol boundary layer will be described that indicates that plasma flows are expected to exist in the equilibrium. The possible role of these plasma flows in producing electron turbulence and irregularities in the charged aerosol boundary layer that may ultimately result in PMSEs is discussed. (C) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.
The response of two Glomus mycorrhizal fungi and a fine endophyte to elevated atmospheric CO2, soil warming and drought
Staddon, PL Gregersen, R Jakobsen, I
GLOBAL CHANGE BIOLOGY 10:11 1909-1921
Plantago lanceolata plants were grown under various environmental conditions in association with the mycorrhizal fungi Glomus mosseae, G. caledonium and a fine endophyte either individually or all together. Using a time-course approach, we investigated the effects of elevated atmospheric CO2 (eCO(2)), soil warming and drought and their interactions on root length colonized (RLC) by mycorrhizal fungi and extraradical mycorrhizal hyphal (EMH) production. Plant growth responded as would be expected to the environmental manipulations. There was no plant growth-independent effect of eCO(2) on mycorrhizal colonization; however, EMH production was stimulated by eCO(2), i.e. there was increased partitioning of below-ground carbon to the EMH. Soil warming directly stimulated both percent RLC by the Glomus species and EMH density; soil warming did not affect RLC by the fine endophyte. Drought decreased percent RLC for the fine endophyte, but not for the Glomus species. The presence of one mycorrhizal fungus did not affect the response of another to the environmental variables. There was no evidence of any interactive effects of the environmental variables on RLC, but there were significant environmental interactions on EMH production. In particular, the stimulatory effects of eCO(2) and soil warming on EMH density were not additive. The results are discussed in terms of the soil carbon cycle, highlighting some crucial gaps in our knowledge. If future environmental changes affect mycorrhizal fungal turnover and respiration, then this could have important implications for the terrestrial carbon cycle.
The impact of global climate change on tropical forest biodiversity in Amazonia
Miles, L Grainger, A Phillips, O
GLOBAL ECOLOGY AND BIOGEOGRAPHY 13:6 553-565
Aim To model long-term trends in plant species distributions in response to predicted changes in global climate. Location Amazonia. Methods The impacts of expected global climate change on the potential and realized distributions of a representative sample of 69 individual Angiosperm species in Amazonia were simulated from 1990 to 2095. The climate trend followed the HADCM2GSa1 scenario, which assumes an annual 1% increase of atmospheric CO2 content with effects mitigated by sulphate forcing. Potential distributions of species in one-degree grid cells were modelled using a suitability index and rectilinear envelope based on bioclimate variables. Realized distributions were additionally limited by spatial contiguity with, and proximity to, known record sites. A size-structured population model was simulated for each cell in the realized distributions to allow for lags in response to climate change, but dispersal was not included. Results In the resulting simulations, 43% of all species became non-viable by 2095 because their potential distributions had changed drastically, but there was little change in the realized distributions of most species, owing to delays in population responses. Widely distributed species with high tolerance to environmental variation exhibited the least response to climate change, and species with narrow ranges and short generation times the greatest. Climate changed most in north-east Amazonia while the best remaining conditions for lowland moist forest species were in western Amazonia. Main conclusions To maintain the greatest resilience of Amazonian biodiversity to climate change as modelled by HADCM2GSa1, highest priority should be given to strengthening and extending protected areas in western Amazonia that encompass lowland and montane forests.
Interpretation of Arctic aerosol properties using cluster analysis applied to observations in the Svalbard area
Treffeisen, R Herber, A Strom, J Shiobara, M Yamagata, TY Holmen, K Kriews, M Schrems, O
TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY 56:5 457-476
Atmospheric aerosols play an important role in global climate change, directly through radiative forcing and indirectly through their effect on cloud properties. Numerous measurements have been performed in the last three decades in order to characterize polar aerosols. Information about aerosol characteristics is needed to calculate induced changes in the Earth’s heat balance. However, this forcing is highly variable in space and time. Accurate quantification of forcing by aerosols will require combined efforts, assimilating information from different sources such as satellite, aircraft and surface-based observations. Adding to the complexity of the problem is that the measurements themselves are often not directly comparable as they vary in spatial/temporal resolution and in the basic properties of the aerosol that they measure. Therefore it is desirable to close the gap between the differences in temporal and spatial resolution and coverage among the observational approaches. In order to keep the entire information content and to treat aerosol variability in a consistent and manageable way an approach has to be achieved which enables one to combine these data. This study presents one possibility for linking together a complex Arctic aerosol data set in terms of parameters, timescale and place of measurement as well as meteorological parameters. A cluster analysis was applied as a pattern recognition technique. The data set is classified in clusters and expressed in terms of mean statistical values, which represent the entire database and its variation. For this study, different time-series of microphysical, optical and chemical aerosol parameters as well as meteorological parameters were analysed. The database was obtained during an extensive aerosol measurement campaign, the ASTAR 2000 (Arctic Study of Tropospheric Aerosol and Radiation) field campaign, with coordinated simultaneous ground-based and airborne measurements in the vicinity of Spitsbergen (Svalbard). Furthermore, longterm measurements at two ground-based sites situated at different altitudes were incorporated into the analysis. The approach presented in this study allows the necessary linking of routine long-term measurements with short-term extensive observations. It also involves integration of intermittent vertical aerosol profile measurements. This is useful for many applications, especially in climate research where the required data coverage is large.
Decomposition of soil and plant carbon from pasture systems after 9 years of exposure to elevated CO2: impact on C cycling and modeling
de Graaff, MA Six, J Harris, D Blum, H van Kessel, C
GLOBAL CHANGE BIOLOGY 10:11 1922-1935
Elevated atmospheric CO2 may alter decomposition rates through changes in plant material quality and through its impact on soil microbial activity. This study examines whether plant material produced under elevated CO2 decomposes differently from plant material produced under ambient CO2. Moreover, a long-term experiment offered a unique opportunity to evaluate assumptions about C cycling under elevated CO2 made in coupled climate-soil organic matter (SOM) models. Trifolium repens and Lolium perenne plant materials, produced under elevated (60 Pa) and ambient CO2 at two levels of N fertilizer (140 vs. 560 kg ha(-1) yr(-1)), were incubated in soil for 90 days. Soils and plant materials used for the incubation had been exposed to ambient and elevated CO2 under free air carbon dioxide enrichment conditions and had received the N fertilizer for 9 years. The rate of decomposition of L. perenne and T. repens plant materials was unaffected by elevated atmospheric CO2 and rate of N fertilization. Increases in L. perenne plant material C : N ratio under elevated CO2 did not affect decomposition rates of the plant material. If under prolonged elevated CO2 changes in soil microbial dynamics had occurred, they were not reflected in the rate of decomposition of the plant material. Only soil respiration under L. perenne, with or without incorporation of plant material, from the low-N fertilization treatment was enhanced after exposure to elevated CO2. This increase in soil respiration was not reflected in an increase in the microbial biomass of the L. perenne soil. The contribution of old and newly sequestered C to soil respiration, as revealed by the C-13-CO2 signature, reflected the turnover times of SOM-C pools as described by multipool SOM models. The results do not confirm the assumption of a negative feedback induced in the C cycle following an increase in CO2, as used in coupled climate-SOM models. Moreover, this study showed no evidence for a positive feedback in the C cycle following additional N fertilization.
Is climate change affecting wolf populations in the High Arctic?
CLIMATIC CHANGE 67:1 87-93
Gobal climate change may affect wolves in Canada’s High Arctic (80degrees N) acting through three trophic levels (vegetation, herbivores, and wolves). A wolf pack dependent on muskoxen and arctic hares in the Eureka area of Ellesmere Island denned and produced pups most years from at least 1986 through 1997. However, when summer snow covered vegetation in 1997 and 2000 for the first time since records were kept, halving the herbivore nutrition-replenishment period, muskox and hare numbers dropped drastically, and the area stopped supporting denning wolves through 2003. The unusual weather triggering these events was consistent with global-climate-change phenomena.
Climate change and the distribution of climatic resources for tourism in North America
Scott, D McBoyle, G Schwartzentruber, M
CLIMATE RESEARCH 27:2 105-117
Tourism is a major sector of the global economy, and it is strongly influenced by climate. At some travel destinations, climate represents the natural resource on which the tourism industry is predicated. Global climate change has the potential to alter the distribution of climate assets among tourism destinations, with implications for tourism seasonality, demand and travel patterns. Changes in the length and quality of the tourism season have considerable implications for the long-term profitability of tourism enterprises and competitive relationships between destinations. This analysis utilizes a ‘tourism climate index’ (TCI) that incorporates 7 climate variables relevant to general tourism activities (i.e. sightseeing) to assess the spatial and temporal distribution of climate resources for tourism in North America under baseline conditions (1961-1990) and 2 climate change scenarios (CGCM2-B2 and HadCM3-A1F1) for the 2050s and 2080s. The analysis found that a substantive redistribution of climate resources for tourism will be possible in the later decades of the 21st century, particularly in the warmer and wetter HadCM3-A1F1 scenario. The number of cities in the USA with ‘excellent’ or’ ideal’ TCI ratings (TCI > 80) in the winter months is likely to increase, so that southern Florida and Arizona could face increasing competition for winter sun holiday travelers and the seasonal ‘snowbird’ market (retirees from Canada and the northern states of the USA, who spend 2 to 6 mo in winter peak and optimal climate destinations). In contrast, lower winter TCI ratings in Mexico suggest it could become less competitive as a winter sun holiday destination. In Canada, a longer and improved warm-weather tourism season may enhance its competitiveness in the international tourism marketplace, with potentially positive implications for its current international tourism account deficit.
Effect of elevated CO2 concentration and vapour pressure deficit on isoprene emission from leaves of Populus deltoides during drought
Pegoraro, E Rey, A Bobich, EG Barron-Gafford, G Grieve, KA Malhi, Y Murthy, R
FUNCTIONAL PLANT BIOLOGY 31:12 1137-1147
To further our understanding of the influence of global climate change on isoprene production we studied the effect of elevated [CO2] and vapour pressure deficit (VPD) on isoprene emission rates from leaves of Populus deltoides Bartr. during drought stress. Trees, grown inside three large bays with atmospheres containing 430, 800, or 1200 mumol mol(-1) CO2 at the Biosphere 2 facility, were subjected to a period of drought during which VPD was manipulated, switching between low VPD ( approximately 1 kPa) and high VPD ( approximately 3 kPa) for several days. When trees were not water-stressed, elevated [CO2] inhibited isoprene emission and stimulated photosynthesis. Isoprene emission was less responsive to drought than photosynthesis. As water-stress increased, the inhibition of isoprene emission disappeared, probably as a result of stomatal closure and the resulting decreases in intercellular [CO2] (C-i). This assumption was supported by increased isoprene emission under high VPD. Drought and high VPD dramatically increased the proportion of assimilated carbon lost as isoprene. When measured at the same [CO2], leaves from trees grown at ambient [CO2] always had higher isoprene emission rates than the leaves of trees grown at elevated [CO2], demonstrating that CO2 inhibition is a long-term effect.
Vulnerability of waterborne diseases to climate change in Canada: A review
Charron, DF Thomas, MK Waltner-Toews, D Aramini, JJ Edge, T Kent, RA Maarouf, AR Wilson, J
JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH-PART A-CURRENT ISSUES 67:20-22 1667-1677
This project addresses two important issues relevant to the health of Canadians: the risk of waterborne illness and the health impacts of global climate change. The Canadian health burden from waterborne illness is unknown, although it presumably accounts for a significant proportion of enteric illness. Recently, large outbreaks with severe consequences produced by E. coli O157:H7 and Cryptosporidium have alarmed Canadians and brought demands for political action. A concurrent need to understand the health impacts of global climate changes and to develop strategies to prevent or prepare for these has also been recognized. There is mounting evidence that weather is often a factor in triggering waterborne disease outbreaks. A recent study of precipitation and waterborne illness in the United States found that more than half the waterborne disease outbreaks in the United States during the last half century followed a period of extreme rainfall. Projections of international global climate change scenarios suggest that, under conditions of global warming most of Canada may expect longer summers, milder winters, increased summer drought, and more extreme precipitation. Excess precipitation, floods, high temperatures, and drought could affect the risk of waterborne illness in Canada. The existing scientific information regarding most weather-related adverse health impacts and on the impacts of global climate change on health in Canada is insufficient for informed decision making. The results of this project address this need through the investigation of the complex systemic interrelationships between disease incidence, weather parameters, and water quality and quantity, and by projecting the potential impact of global climate change on those relationships.
The potential distribution of zebra mussels in the United States
Drake, JM Bossenbroek, JM
BIOSCIENCE 54:10 931-941
The range expansion of zebra mussels (Dreissena polymorpha) in North America has been rapid and costly in both economic and ecological terms. joint social, political, and scientific ventures such as the 100th Meridian Initiative aim to reduce the spread of zebra mussels by eliminating the unintended transport of the species and preventing its westward expansion. Here we forecast the potential distribution of zebra mussels in the United States by applying a machine-learning algorithm for nonparametric prediction of species distributions (genetic algorithm for rule-set production, or GARP) to data about the current distribution of zebra mussels in the United States and 11 environmental and geological covariates. Our results suggest that much of the American West will be uninhabitable for zebra mussels. Nonetheless, some catchments along the West Coast and in the southeastern United States exhibit considerable risk of invasion and should be monitored carefully. Possible propagule dispersal to these places should be managed proactively.
Responses of foraminiferal isotopic variations at ODP Site 1143 in the southern South China Sea to orbital forcing
Tian, J Wang, PX Cheng, XR
SCIENCE IN CHINA SERIES D-EARTH SCIENCES 47:10 943-953
The foraminiferal delta(18)O and delta(13)C records for the past 5 Ma at ODP Site 1143 reveal the linear responses of the Plio-Pleistocene climatic changes in the southern South China Sea to orbital forcing at the obliquity and precession bands. The phase of the 5180 variations with the orbital forcing is opposite to that of the delta(13)C, which may be caused by the frequent El Nino events from the equatorial Pacific. The amplification of the Northern Hemisphere Ice Sheet at similar to3.3 Ma probably affected the development of the 100-ka climatic cycles. Its further spreading may spur the 100-ka climatic cycle to become the dominant cycle in the late Pleistocene. The “Mid-Pleistocene Transition” event has localized influence on the isotopic variations in the southern South China Sea. The foraminiferal delta(13)C records for the past 5 Ma at Site 1143 are highly coherent with the orbital forcing at the long eccentricity band, and lead the delta(18)O records at the shorter eccentricity band, highlighting the importance of the carbon cycle in the global climate change.
Can climate data from METEOSAT improve wildlife distribution models?
Suarez-Seoane, S Osborne, PE Rosema, A
ECOGRAPHY 27:5 629-636
Global climate change generated by human activities is likely to affect agroecosystems in several ways: reinforcing intensification in northern and western Europe, and extensification in the Mediterranean countries. If we are to predict the consequences of global warming for wildlife, distribution models have to include climate data. The METEOSAT temporal series from EWBMS offers an attractive alternative to using climatic surfaces derived from ground stations. The aim of this paper is to test whether this climatic satellite data can improve the distribution models obtained previously by Suarez-Seoane et al. using habitat variables for three agro-steppe bird species: great bustard, little bustard and calandra lark in Spain. Rainfall, radiation balance, evapotranspiration and soil moisture images were incorporated together with the other variables used as predictors in the published stepwise GAM models. Changes in the predicted distributions from the habitat only and climate-habitats models were assessed by reference to the CORINE land cover categories. Inclusion of climatic variables from METEOSAT led to statistically superior models for all three species. There were large differences in the climatic variables selected and the original variables dropped among the species. Evapotranspiration variables were the most frequently selected. Maps of the differences between the habitat and climate-habitat models showed very different patterns for the three species. Inclusion of climate variables led to a wider range of land cover types being deemed suitable. Despite the statistical superiority of models, care is needed in deciding whether to use climatic variables because they may emphasize the fundamental rather than the realized niche. Used together, however, habitat and climate models can provide new insights into factors limiting species distributions and how they may respond to climate change.
Age-related environmental sensitivity and weather mediated nestling mortality in white storks Ciconia ciconia
Jovani, R Tella, JL
ECOGRAPHY 27:5 611-618
We studied environmental sensitivity and mortality related to weather inclemency in white stork nestlings Ciconia ciconia in their southern European boundary (Donana, SW Spain). The study of homeothermy acquisition and fault bars (i.e. a measure of stress on feathers) revealed that stork nestlings were specially sensitive to environmental conditions occurring before 20 d of age. Accordingly, most of nestling mortality concentrated during this sensitive period: 91% of deaths corresponded to nestlings younger than 20 d, 73% concentrating on nestlings up to 10 d-old. Nestling mortality and total breeding failure were highly variable among years, being especially high when rainy periods coincided with the early live of nestlings (between 1 April and 15 May). Maximum temperatures had a positive correlation with breeding success and nestling survival but this effect disappeared when controlling for rainfall. Our results are in agreement with previous studies conducted in other white stork populations in other latitudes. We suggest that this could be the result of a low homeothermy capacity of young nestlings jointly with an early breeding phenology that expose white storks to rain, but not to high temperatures. In the context of global climate change we suggest that the current decrease on spring rainfall could increase nestling survival while punctual rainy springs could have a negative effect on the reproduction of white storks.
PARAGON - An integrated approach for characterizing aerosol climate impacts and environmental interactions
Diner, DJ Ackerman, TP Anderson, TL Bosenberg, J Braverman, AJ Charlson, RJ Collins, WD Davies, R Holben, BN Hostetler, CA Kahn, RA Martonchik, JV Menzies, RT Miller, MA Ogren, JA Penner, JE Rasch, PJ Schwartz, SE Seinfeld, JH Stephens, GL Torres, O Travis, LD Wielicki, BA Yu, B
BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 85:10 1491-+
Aerosols exert myriad influences on the earth’s environment and climate, and on human health. The complexity of aerosol-related processes requires that information gathered to improve our understanding of climate change must originate from multiple sources, and that effective strategies for data integration need to be established. While a vast array of observed and modeled data are becoming available, the aerosol research community currently lacks the necessary tools and infrastructure to reap maximum scientific benefit from these data. Spatial and temporal sampling differences among a diverse set of sensors, nonuniform data qualities, aerosol mesoscale variabilities, and difficulties in separating cloud effects are some of the challenges that need to be addressed. Maximizing the long-term benefit from these data also requires maintaining consistently well-understood accuracies as measurement approaches evolve and improve. Achieving a comprehensive understanding of how aerosol physical, chemical, and radiative processes impact the earth system can be achieved only through a multidisciplinary, inter-agency, and international initiative capable of dealing with these issues. A systematic approach, capitalizing on modern measurement and modeling techniques, geospatial statistics methodologies, and high-performance information technologies, can provide the necessary machinery to support this objective. We outline a framework for integrating and interpreting observations and models, and establishing an accurate, consistent, and cohesive long-term record, following a strategy whereby information and tools of progressively greater sophistication are incorporated as problems of increasing complexity are tackled. This concept is named the Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON). To encompass the breadth of the effort required, we present a set of recommendations dealing with data interoperability; measurement and model integration; multisensor synergy; data summarization and mining; model evaluation; calibration and validation; augmentation of surface and in situ measurements; advances in passive and active remote sensing; and design of satellite missions. Without an initiative of this nature, the scientific and policy communities will continue to struggle with understanding the quantitative impact of complex aerosol processes on regional and global climate change and air quality.
Nitrogen input mediates the effect of free-air CO2 enrichment on mycorrhizal fungal abundance
Staddon, PL Jakobsen, I Blum, H
GLOBAL CHANGE BIOLOGY 10:10 1678-1688
Plots containing Lolium perenne L., Trifolium repens L. or a mixture of both plant species were exposed to elevated atmospheric CO2 (eCO(2)) for 10 consecutive seasons using free-air CO2 enrichment technology at ETH Zurich, Switzerland. The CO2 treatment was crossed with a two-level nitrogen (N) fertilization treatment. In the tenth year, soil samples were collected on three occasions through the growing season to assess the impact of eCO(2) and N fertilization on mycorrhizal fungal abundance. Soil moisture content, which varied with harvest date, was linked to the vegetation type and was higher under eCO(2). Root weight density was affected by vegetation type: lower for clover, higher for grass. Root weight density was stimulated by eCO(2) and decreased by high N fertilization. The percent root length colonized by mycorrhizal fungi was lowest in the clover plots and highest in the grass plots. High N significantly decreased root length colonized. There was no overall effect of eCO(2) on root length colonized; however, there was a significant eCO(2)x N interaction: eCO(2) increased root length colonized at high N, but decreased root length colonized at low N. Extraradical mycorrhizal hyphal density was linked to soil moisture content. Extraradical mycorrhizal hyphal density was not affected by eCO(2) or high N individually, but as for root length colonized, there was a significant eCO(2)x N interaction: eCO(2) increased extraradical mycorrhizal hyphal density at low N but not at high N. These environmental effects on root colonization and external mycorrhizal hyphae were independent of soil moisture content and root weight density. This field study demonstrated a significant mediating effect of N fertilization on the response of arbuscular mycorrhizal fungi to eCO(2) irrespective of any change in root biomass.
Risk and climate change: Perceptions of key policy actors in Canada
RISK ANALYSIS 24:5 1395-1406
This article examines factors that predict perceptions of risk associated with global climate change. The research focuses on the perceptions of those associated with climate change policy making in the prairie region of Canada. The data are from an online survey (n = 851) of those policy actors. The analysis integrates several dominant approaches to the study of risk perception: psychometric approaches that examine the effects of cognitive structure; demographic assessments that examine, for example, differences in perception based on gender or family status; and political approaches that suggest that one’s position in the policy process may affect his or her perceived risk. Attitudes toward climate change are to a degree predicted by all of these factors, but only when indirect effects are observed. Sociodemographic characteristics have little direct effect on perceived risk, but do affect general beliefs that affect risk perceptions. Perceived risk is related more strongly to these general beliefs or world views than to more specific beliefs about the effects of climate change on weather patterns. Position within the policy process also contributes to our understanding of perceptions, with industry and governmental actors demonstrating similar attitudes, which contrast with environmental groups and university researchers.
Divergent pheromone-mediated insect behaviour under global atmospheric change
Mondor, EB Tremblay, MN Awmack, CS Lindroth, RL
GLOBAL CHANGE BIOLOGY 10:10 1820-1824
While the effects of global atmospheric changes on vegetation and resulting insect populations(‘bottom-up interactions’) are being increasingly studied, how these gases modify interactions among insects and their natural enemies (‘top-down interactions’) is less clear. As natural enemy efficacy is governed largely by behavioural mechanisms, altered prey finding and prey defence may change insect population dynamics. Here we show that pheromone-mediated escape behaviours, and hence the vulnerability of insects to natural enemies, are divergent under atmospheric conditions associated with global climate change. Chaitophorus stevensis, a common aphid on trembling aspen trees, Populus tremuloides, have diminished escape responses in enriched carbon dioxide (CO2) environments, while those in enriched ozone (O-3) have augmented escape responses, to alarm pheromone. These results suggest that divergent pheromone-mediated behaviours could alter predator-prey interactions in future environments.
Municipal heat wave response plans
Bernard, SM McGeehin, MA
AMERICAN JOURNAL OF PUBLIC HEALTH 94:9 1520-1522
Approximately 400 people die from extreme heat each year in the United States, and the risk of heat waves may increase as a result of global climate change. Despite the risk of heat-related morbidity and mortality, many cities lack written heat response plans. In a review of plans from 18 cities at risk for heat-related mortality, we found that many cities had inadequate or no heat response plans. This is an important area for further investigation and government attention.
Sea level rise affecting the Vietnamese Mekong Delta: Water elevation in the flood season and implications for rice production
Wassmann, R Hien, NX Hoanh, CT Tuong, TP
CLIMATIC CHANGE 66:1-2 89-107
In this study, we assessed the impact of sea level rise, one of the most ascertained consequences of global climate change, for water levels in the Vietnamese Mekong Delta (VMD). We used a hydraulic model to compute water levels from August to November-when flooding is presently critical-under sea level rise scenarios of 20 cm (= Delta20) and 45 cm (= Delta45), respectively. The outputs show that the contour lines of water levels will be shifted up to 25 km (Delta20) and 50 km (Delta45) towards the sea due to higher sea levels. At the onset of the flood season ( August), the average increment in water levels in the Delta is 14.1 cm (Delta20) and 32.2 cm (Delta45), respectively. At the peak of the flood season ( October), high discharge from upstream attenuates the increment in water level, but average water level rise of 11.9 cm (Delta20) and 27.4 cm (Delta45), respectively, still imply a substantial aggravation of flooding problems in the VMD. GIS techniques were used to delineate areas with different levels of vulnerability, i.e., area with high (2.3 mio ha = 60% of the VMD), medium (0.6 mio ha = 15%) and low (1 mio ha = 25%) vulnerability due to sea level rise. Rice production will be affected through excessive flooding in the tidally inundated areas and longer flooding periods in the central part of the VMD. These adverse impacts could affect all three cropping seasons, Mua (main rainfed crop), Dong Xuan (Winter-Spring) and He Thu (Summer-Autumn) in the VMD unless preventive measures are taken.
Predicting the distribution of ground beetle species (Coleoptera, Carabidae) in Britain using land cover variables
Eyre, MD Rushton, SP Luff, ML Telfer, MG
JOURNAL OF ENVIRONMENTAL MANAGEMENT 72:3 163-174
Predictions of plant and animal species distributions are important for conservation and for the assessment of large-scale ecosystem change. Land cover data are becoming more widely available for use in land management and conservation. We use a logistic regression modelling approach to investigate the utility of these data for modelling. The relationship between the distribution of 137 British ground beetles species and land cover was investigated using data from 1687 10 kin national grid squares. Land cover data were simplified using ordination and the axes used as predictors in logistic regression with presence absence data for individual beetle species as response variables. Significant regression models were generated for all species with first and second axis scores. The amounts of variation explained by models were generally low, but predictions derived from models generally matched the known distributions of the species in Britain. Species with coastal preferences were poorly modelled and predicted to occur throughout lowland Britain whilst a number of species occurring in southern Britain were predicted to occur into Scotland. A validation exercise comparing model predictions with new data from a survey of 59 10 km(2) produced mixed results with the distribution of grassland species being better predicted than riverine species. Jackknifing was used to assess the robustness of models for four species which differed in their apparent responses to the land cover variables. Methods for improving the predictive power of these models and their potential for use in assessing the impact of global climate change are discussed. (C) 2004 Elsevier Ltd. All rights reserved.
Wind-mediated diel variation in flow speed in a Jamaican back reef environment: Effects on ecological processes
Genovese, SJ Witman, JD
BULLETIN OF MARINE SCIENCE 75:2 281-293
The movement of water plays an important role in a number of physiological (e.g., metabolic rate, nutrient uptake) and ecological (e.g., foraging, fertilization) processes for coral reef organisms. In the back reef of Discovery Bay, Jamaica, daytime mean flow speeds were on average, 61% greater than at night during a given 24 hr period. Wind speed was a significant predictor of flow speed in these shallow water environments, with the variation in wind speed able to explain 30% of the variation in flow speed. Porter’s (1985) yearlong wind speed record in Discovery Bay indicated that the time of maximum daily wind speed occurred during daylight hours for 93% of the year. Activity of the fireworm, Hermodice carunculata (Pallas, 1766), represented by total abundance in six, 1 x 30 m transects was negatively correlated with flow speed. Atmospheric and oceanographic conditions enhancing wind-dependent water flow in back reef environments include prevalent tradewinds and negligible tidal currents, which suggests that the diel variation in flow speed documented for Discovery Bay may be a common phenomenon in similar environments. Such predictable environmental variability may be an important selective agent shaping the evolution of diel rhythms of reef invertebrates and algae. Therefore, recent atmospheric and climatological shifts (e.g., frequency of El Nino events, global climate change) may exert additional selective pressure on the organisms found in these environments.
Estimating burned area for Tropical Africa for the year 1990 with the NOAA-NASA Pathfinder AVHRR 8km land dataset
Ruiz, JAM Garbin, MC
INTERNATIONAL JOURNAL OF REMOTE SENSING 25:17 3389-3410
The international scientific community recognizes the long-term monitoring of biomass burning as important for global climate change, vegetation disturbance and land cover change research on the Earth’s surface. Although high spatial resolution satellite images may offer a more detailed view of land surfaces, their limited area coverage and temporal sampling have restricted their use to local research rather than global monitoring. Low spatial resolution images provide an invaluable source for the detection of burned areas in vegetation cover (scars) at global scale along time. However, the automated burned area mapping algorithm applicable at continental or global scale must be sufficiently robust to accommodate the global variation in burned scar signals. Here, the estimation of the percentage of a pixel area affected by a fire is crucial. In a first step, an empirical method is used which is based on a function between the change in Normalized Difference Vegetation Index (NDVI) and the surface area affected by fire. Next, a new statistical method, based on the Monte Carlo algorithm, is applied to compute probabilities of burned pixels percentages in different neighbourhood conditions.
Neighbour identity modifies effects of elevated temperature on plant performance in the High Arctic
Dormann, CF van der Wal, R Woodin, SJ
GLOBAL CHANGE BIOLOGY 10:9 1587-1598
Competition among plants in extreme environments such as the High Arctic has often been described as unimportant, or even nonexistent; environmental factors are thought to overrule any negative plant-plant interactions. However, few studies have actually addressed this question experimentally in the Arctic, and those that did found only little evidence for competition. Such species interactions will presumably become more important in the future, as Global Climate Change takes effect on terrestrial ecosystems. We investigated plant-plant interactions in the High Arctic, following the growth of Luzula confusa and Salix polaris in pure and mixed stands, and under elevated-temperature treatment over 2 years. To understand the mechanisms of competition, a parallel experiment was undertaken in phytotrons, manipulating competition, temperature and nutrient availability. Our findings indicate that competition is acting in the natural vegetation, and that climatic warming will alter the balance of interactions in favour of the dwarf shrub S. polaris. The phytotron experiment suggested that the mechanism is a higher responsiveness of Salix to nutrient availability, which increased under warming in the field. While Luzula showed a positive response to higher temperature in the lab, its performance in mixed stands in the field was actually reduced by warming, indicating a competitive repression of growth by Salix. The growth of Salix was also reduced by the presence of Luzula, but it was still able to profit from warming. Our findings suggest that climatic warming will result in greater shrub dominance of High Arctic tundra, but we also conjecture that grazing could reverse the situation to a graminoid-dominated tundra. These two divergent scenarios would have different implications for ecosystem feedbacks to climatic change.
Variation in climate warming along the migration route uncouples arrival and breeding dates
Ahola, M Laaksonen, T Sippola, K Eeva, T Rainio, K Lehikoinen, E
GLOBAL CHANGE BIOLOGY 10:9 1610-1617
Migratory species are of special concern in the face of global climate change, since they may be affected by changes in the wintering area, along the migration route and at the breeding grounds. Here we show that migration and breeding times of a trans-Saharan migrant, the pied flycatcher Ficedula hypoleuca, closely follow local temperatures along the migration route and at the breeding grounds. Because of differences in long-term temperature trends of short within-spring periods, the migration period and the time interval between migration and breeding dates of this species have extended in SW Finland. Temperatures in northern parts of Central Europe have risen at the time when the first migrants arrive there, facilitating their migration northward. Temperatures later in the spring have not changed, and the last individuals arrive at the same time as before. The timing of breeding has not advanced because temperatures at the breeding site after arrival have not changed. These results show that the pied flycatchers can speed up their migration in response to rising temperatures along the migration route. Our results strongly indicate that the effects of climate change have to be studied at the appropriate time and geographical scales for each species and population concerned.
Climate change: Conflict of observational science, theory, and politics
AAPG BULLETIN 88:9 1211-1220
Debate over whether human activity causes Earth climate change obscures the immensity of the dynamic systems that create and maintain climate on the planet. Anthropocentric debate leads people to believe that they can alter these planetary dynamic systems to prevent what they perceive as negative climate impacts on human civilization. Although politicians offer simplistic remedies, such as the Kyoto Protocol, global climate continues to change naturally. Better planning for the inevitable dislocations that have followed natural global climate changes throughout human history requires us to accept the fact that climate will change, and that human society must adapt to the changes. Over the last decade, the scientific literature reported a shift in emphasis from attempting to build theoretical models of putative human impacts on climate to understanding the planetwide dynamic processes that are the natural climate drivers. The current scientific literature is-beginning to report the history of past climate change, the extent of natural climate variability, natural system drivers, and the episodicity of many climate changes. The scientific arguments have broadened from focus upon human effects on climate to include the array of natural phenomena that have driven global climate change for eons. However, significant political issues with long-term social consequences continue their advance. This paper summarizes recent scientific progress in climate science and arguments about human influence on climate.
Coral reefs in a century of rapid environmental change
SYMBIOSIS 37:1-3 1-31
Coral reefs are the most diverse marine ecosystem and embrace possibly millions of plant, animal and protist species. Mutualistic symbioses are a fundamental feature of coral reefs that have been used to explain their structure, biodiversity and existence. Complex inter-relationships between hosts, habitats and symbionts belie closely coupled nutrient and community dynamics that create the circumstances for “something from nothing” (or the “oasis in a nutrient desert”). The flip side of these dynamics is a close dependency between species, which results in a series of non-linear relationships as conditions change. These responses are being highlighted as anthropogenic influences increase across the world’s tropical and subtropical coastlines. Caribbean as well as Indo-Pacific coral populations are now in a serious decline in many parts of the world. This has resulted in a significant reorganization of how coral reef ecosystems function. Among the spectra of changes brought about by humans is rapid climate change. Mass coral bleaching - the loss of the dinoflagellate symbionts from reef-building corals - and mortality has affected the world’s coral reefs with increasing frequency and intensity since the late 1970s. Mass bleaching events, which often cover thousands of square kilometres of coral reefs, are triggered by small increases (+1-3degreesC) in water temperature. These increases in sea temperature are often seen during warm phase weather conditions (e.g. ENSO) and are increasing in size and magnitude. The loss of living coral cover (e.g. 16% globally in 1998, an exceptionally warm year) is resulting in an as yet unspecified reduction in the abundance of a myriad of other species. Projections from general circulation models (GCM) used to project changes in global temperature indicate that conditions even under the mildest greenhouse gas emission scenarios may exceed the thermal tolerances of most reef-building coral communities. Research must now explore key issues such as the extent to which the thermal tolerances of corals and their symbionts are dynamic if bleaching and disease are linked; how the loss of high densities of reef-building coral will affect other dependent species; and, how the loss of coral populations will affect the millions of people globally who depend on coral reefs for their daily survival.
High-resolution vegetation and climate change associated with Pliocene Australopithecus afarensis
Bonnefille, R Potts, R Chalie, F Jolly, D Peyron, O
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 101:33 12125-12129
Plio-Pleistocene global climate change is believed to have had an important influence on local habitats and early human evolution in Africa. Responses of hominin lineages to climate change have been difficult to test, however, because this procedure requires well documented evidence for connections between global climate and hominin environment. Through high-resolution pollen data from Hadar, Ethiopia, we show that the hominin Australopithecus afarensis accommodated to substantial environmental variability between 3.4 and 2.9 million years ago. A large biome shift, up to 5degreesC cooling, and a 200- to 300-mm/yr rainfall increase occurred just before 3.3 million years ago, which is consistent with a global marine delta(18)O isotopic shift.
The gypsy moth life stage model: landscape-wide estimates of gypsy moth establishment using a multi-generational phenology model
ECOLOGICAL MODELLING 176:1-2 155-171
A multi-generational model of gypsy moth phenology was developed from existing literature and used to assess the risk of establishment of this exotic pest across North America based on the suitability of 4457 locations in satisfying the temperature requirements for seasonal development. Approximately 595 million hectares of North America is estimated to be climatically suitable for gypsy moth establishment. Limits to the potential range exist in the southern United States because of limits to diapause development, and in northern Canada because of slower prediapause and larval development. A 1.5 degreesC increase in mean daily maximum and minimum temperatures, as might occur with global climate change, would result in a range expansion in the north, a range contraction in the south, and a net increase in range of approximately 16%. The model is described and the probable limitations to establishment are discussed. Crown Copyright (C) 2004 Published by Elsevier B.V. All rights reserved.
Environmental magnetic record of paleoclimate change from the Eocene-Oligocene stratotype section, Massignano, Italy
Jovane, L Florindo, F Dinares-Turell, J Turell, S
GEOPHYSICAL RESEARCH LETTERS 31:15 -
A high-resolution environmental magnetic study of the Massignano section, Italy (Global Stratotype Section and Point for the Eocene-Oligocene boundary), has been performed to test whether a clear magnetic signature associated with climatic change is recognizable in this record. Our results reveal the existence of alternating intervals with high and low magnetic mineral concentrations similar to the pattern of rock magnetic property variations observed from an environmental magnetic study of the CIROS-1 sediment core from Antarctica. These results suggest that an external forcing mechanism drove the sedimentary response to global climate change prior to the major Oi-1 cooling event at the Eocene-Oligocene boundary.
Nitrate assimilation in plant shoots depends on photorespiration
Rachmilevitch, S Cousins, AB Bloom, AJ
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 101:31 11506-11510
Photorespiration, a process that diminishes net photosynthesis by approximate to25% in most plants, has been viewed as the unfavorable consequence of plants having evolved when the atmosphere contained much higher levels of carbon dioxide than it does today. Here we used two independent methods to show that exposure of Arabidopsis and wheat shoots to conditions that inhibited photorespiration also strongly inhibited nitrate assimilation. Thus, nitrate assimilation in both dicotyledonous and monocotyledonous species depends on photorespiration. This previously undescribed role for photorespiration (i) explains several responses of plants to rising carbon dioxide concentrations, including the inability of many plants to sustain rapid growth under elevated levels of carbon dioxide; and (h) raises concerns about genetic manipulations to diminish photorespiration in crops.
Larval salamander response to uv radiation and predation risk: Color change and microhabitat use
Garcia, TS Stacy, J Sih, A
ECOLOGICAL APPLICATIONS 14:4 1055-1064
Adaptations to avoid or cope with harmful ultraviolet radiation (UVR) have evolved in many amphibian species. Sublethal levels of UVR can select for simple responses in larval amphibians, such as dark pigmentation or preference for UVR-protected microhabitats (i.e., under cover or in deep water). This Study focuses on color response to UVR, and whether avoidance behaviors like refuge use and depth choice depend on larval body color. We quantified responses to ambient levels of UVR in four experiments in semi-field conditions using two sister species of salamander larvae that differ in their evolutionary history of UVR exposure. Both Ambystoma barbouri and A. texanum larvae darkened in response to UVR, and when given the choice of refuge, significantly increased the proportion of time spent in hiding. Additionally, both species used deeper microhabitats when exposed to UVR, but only A. barbouri larvae showed a preference for shallow waters when UVR was blocked out. Neither of these behaviors seemed to be color dependent, with larvae from both species taking refuge and preferring deep water in the presence of UVR, regardless of body color. Interesting behavioral trade-offs arose when larvae were confronted with conflicting selection pressures from UVR and predation risk. Risk from predatory fish forces larvae to shallow areas, while UVR forces larvae into deeper water. Thus, the combination of the two selection pressures creates a conflict in optimal depth choice. Faced with this conflict, A. barbouri preferred deeper, risky areas to shallow water with high UVR exposure. Ambystoma texanum responded to predation risk with a preference for shallow water, but did not significantly alter depth in response to UVR. Given the opportunity to mediate exposure to UVR and predation risk by altering depth choices, neither species changed color in response to either UVR or predation risk. Overall, these changes in behavior and color may affect larval feeding, competition, and predation rates and could thus alter aquatic community structure.
Biodiversity, biosphere reserves, and the big apple - A study of the New York Metropolitan Region
Solecki, WD Rosenzweig, C
URBAN BIOSPHERE AND SOCIETY: PARTNERSHIP OF CITIES 1023: 105-124
The objectives of this article were to assess the dimensions of biodiversity-urban society interactions within the New York Metropolitan Region, a 31-county area with a population of 21.5 million, and to explore pathways to reconcile dysfunctional relationships between these two ever-entwined systems. The article builds on the premise that urban biodiversity exists at a crucial nexus of ecological and societal interactions, linking local, regional, and global scales, and that urban ecologies are projected to become even more dynamic in the future, particularly as a result of global climate change. The pathway proposed to reconcile the biodiversity-urban society relationships is the incorporation of biosphere reserve strategies into regional environmental planning efforts focused on the New York/New Jersey Harbor/Estuary specifically and on the greater New York Metropolitan Region in general. The concepts of the “ecological footprint” and vulnerability to global environmental change are used to analyze the current interactions between biodiversity and urban society, and to evaluate the efficacy of adopting biosphere reserve strategies in the region. New York has long been at the forefront of American environmentalism and landscape planning. Coupled with this history is a still small but growing interest in regional environmental planning efforts (e.g., the U.S. EPA Harbor Estuary Program) and green infrastructure (e.g., the 2002 Humane Metropolis Conference organized by the Ecological Cities Project). The research presented here aims to contribute to these nascent activities. As a megacity, New York may serve as a model for other major cities of the world.
Photosynthetic down-regulation over long-term CO2 enrichment in leaves of sour orange (Citrus aurantium) trees
Adam, NR Wall, GW Kimball, BA Idso, SB Webber, AN
NEW PHYTOLOGIST 163:2 341-347
Understanding how trees are affected by a long-term increase in atmospheric CO2 is crucial to understanding the future impact of global climate change. Measurements of photosynthetic characteristics were made in sour orange trees (Citrus aurantium) growing under an enhanced CO2 atmosphere and N-replete soil for 14 yr to determine whether photosynthetic down-regulation had occurred. Photosynthesis, A : C-i gas exchange relationships and Rubisco activity and content were measured throughout the 14th year of the experiment. The CO2-induced enhancement ratio of photosynthesis was calculated and compared with estimates of the enhancement of cumulative wood biomass production. Content of the large subunit of Rubisco was significantly reduced by CO2 enrichment indicating that down-regulation had occurred. A high correlation between the CO2-induced enhancement of photosynthesis and the enhancement of cumulative wood biomass production suggested that the decline in wood biomass production was closely related to the decline in photosynthesis. These results indicate that long-term CO2 enrichment can result in photosynthetic down-regulation in leaves of trees, even under nonlimiting N conditions. (C) New Phytologist (2004). No claim to original US government works.
Response of different decomposer communities to the manipulation of moisture availability: potential effects of changing precipitation patterns
Taylor, AR Schroter, D Pflug, A Wolters, V
GLOBAL CHANGE BIOLOGY 10:8 1313-1324
The potential impacts of changes in precipitation patterns associated with global climate change on the relationship between soil community diversity and litter decomposition were investigated. For a period of ca. 5 months, two decomposer communities in litterbags (1000 and 45 mum mesh size) containing spruce litter were subjected to two irrigation treatments: constant and fluctuating (drying/rewetting) moisture conditions. The latter were expected to induce moisture stress on the decomposer communities. The two mesh sizes were used to exclude different faunal components from the decomposer communities. The 1000 mum mesh excluded only the macrofauna, whereas the 45 mum mesh excluded both the macro- and mesofauna. In the short-term perspective of the present study, mesofauna abundance showed no response to imposed fluctuating moisture conditions. Irrespective of the presence of mesofauna, mass loss, microbial biomass and the control mechanisms, regulating carbon mineralization appeared unaffected by fluctuating moisture conditions. The reduction in the functional/structural diversity of the decomposer communities in the 45 mum litterbags resulted in strongly increased Nematoda abundance but it did not alter the response of Nematoda to fluctuating moisture conditions. Processes in the nitrogen (N)-cycle and mass loss were sensitive indicators of changes in the structural and functional complexity of decomposer communities. However, a negative effect of fluctuating moisture conditions on extractable N was coupled to the presence of mesofauna. Extremes in rainfall patterns, generated by climate change, may have a negative impact on the availability of nutrients, particularly N, for plants. This effect could be amplified by an additional impoverishment in the structural and functional complexity of the respective decomposer communities.
Global climate change and infectious disease
Parola, R Raoult, D
ARCHIVES DE PEDIATRIE 11:8 1018-1025
Cell death and degeneration in the symbiotic dinoflagellates of the coral Stylophora pistillata during bleaching
Franklin, DJ Hoegh-Guldberg, P Jones, RJ Berges, JA
MARINE ECOLOGY-PROGRESS SERIES 272: 117-130
Rising sea temperatures are increasing the incidences of mass coral bleaching (the dissociation of the coral-algal symbiosis) and coral mortality. In this study, the effects of bleaching (induced by elevated light and temperature) on the condition of symbiotic dinoflagellates (Symbiodinium sp.) within the tissue of the hard coral Stylophora pistillata (Esper) were assessed using a suite of techniques. Bleaching of S. pistillata was accompanied by declines in the maximum potential quantum yield of photosynthesis (F-v/F-m, measured using pulse amplitude modulated [PAM] fluorometry), an increase in the number of Sytox-green-stained algae (indicating compromised algal membrane integrity and cell death), an increase in 2’,7’-dichlorodihydrofluroscein diacetate (H(2)DCFDA)stained algae (indicating increased oxidative stress), as well as ultrastructural changes (vacuolisation, losses of chlorophyll, and an increase in accumulation bodies). Algae expelled from S. pistillata exhibited a complete disorganisation of cellular contents; expelled cells contained only amorphous material. In situ samples taken during a natural mass coral bleaching event on the Great Barrier Reef in February 2002 also revealed a high number of Sytox-labelled algae cells in symbio. Dinoflagellate degeneration during bleaching seems to be similar to the changes resulting from senescence-phase cell death in cultured algae. These data support a role for oxidative stress in the mechanism of coral bleaching and highlight the importance of algal degeneration during the bleaching of a reef coral.
Identity and diversity of coral endosymbionts (zooxanthellae) from three Palauan reefs with contrasting bleaching, temperature and shading histories
Fabricius, KE Mieog, JC Colin, PL Idip, D Van Oppen, MJH
MOLECULAR ECOLOGY 13:8 2445-2458
The potential of corals to associate with more temperature-tolerant strains of algae (zooxanthellae, Symbiodinium) can have important implications for the future of coral reefs in an era of global climate change. In this study, the genetic identity and diversity of zooxanthellae was investigated at three reefs with contrasting histories of bleaching mortality, water temperature and shading, in the Republic of Palau (Micronesia). Single-stranded conformation polymorphism and sequence analysis of the ribosomal DNA internal transcribed spacer (ITS)1 region was used for genotyping. A chronically warm but partly shaded coral reef in a marine lake that is hydrographically well connected to the surrounding waters harboured only two single-stranded conformation polymorphism profiles (i.e. zooxanthella communities). It consisted only of Symbiodinium D in all 13 nonporitid species and two Porites species investigated, with the remaining five Porites harbouring C.. Despite the high temperature in this lake (> 0.5degrees above ambient), this reef did not suffer coral mortality during the (1998) bleaching event, however, no bleaching-sensitive coral families and genera occur in the coral community. This setting contrasts strongly with two other reefs with generally lower temperatures, in which 10 and 12 zooxanthella communities with moderate to low proportions of clade D zooxanthellae were found. The data indicate that whole coral assemblages, when growing in elevated seawater temperatures and at reduced irradiance, can be composed of colonies associated with the more thermo-tolerant clade D zooxanthellae. Future increases in seawater temperature might, therefore, result in an increasing prevalence of Symbiodinium phylotype D in scleractinian corals, possibly associated with a loss of diversity in both zooxanthellae and corals.
Quantifying the water vapour feedback associated with post-Pinatubo global cooling
Forster, PMD Collins, M
CLIMATE DYNAMICS 23:2 207-214
There is an ongoing important debate about the role of water vapour in climate change. Predictions of future climate change depend strongly on the magnitude of the water vapour feedback and until now models have almost exclusively been relied upon to quantify this feedback. In this work we employ observations of water vapour changes, together with detailed radiative calculations to estimate the water vapour feedback for the case of the Mt. Pinatubo eruption. We then compare our observed estimate with that calculated from a relatively large ensemble of simulations from a complex coupled climate model. We calculate an observed water vapour feedback parameter of -1.6 Wm(-2) K-1, with uncertainty placing the feedback parameter between -0.9 to -2.5 Wm(-2) K-1. The uncertain is principally from natural climate variations that contaminate the volcanic cooling. The observed estimates are consistent with that found in the climate model, with the ensemble average model feedback parameter being -2.0 Wm(-2) K-1, with a 5-95% range of -0.4 to -3.6 Wm(-2) K-1 (as in the case of the observations, the spread is due to an inability to separate the forced response from natural variability). However, in both the upper troposphere and Southern Hemisphere the observed model water vapour response differs markedly from the observations. The observed range represents a 40%-400% increase in the magnitude of surface temperature change when compared to a fixed water vapour response and is in good agreement with values found in other studies. Variability, both in the observed value and in the climate model’s feedback parameter, between different ensemble members, suggests that the long-term water vapour feedback associated with global climate change could still be a factor of 2 or 3 different than the mean observed value found here and the model water vapour feedback could be quite different from this value; although a small water vapour feedback appears unlikely. We also discuss where in the atmosphere water vapour changes have their largest effect on surface climate.
Mycorrhizal fungi as drivers of ecosystem processes in heathland and boreal forest biomes
Read, DJ Leake, JR Perez-Moreno, J
CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE 82:8 1243-1263
The importance of mycorrhizas in heathland and boreal forest biomes, which together cover much of the landmass of the Northern Hemisphere and store most of the global stocks of carbon, is reviewed. The taxonomic affinities of the organisms forming these symbiotic partnerships are assessed, and the distinctive structural features of the ericoid mycorrhizas of heathland dwarf shrubs and the ectomycorrhizas of boreal forest trees are described. It is stressed that neither in terms of the geographical distribution of the plants nor in terms of the occurrence of their characteristic mycorrhizas in the soil profile should these biomes be considered to be mutually exclusive. What unites them is their apparent affinity for acidic organic soils of inherently low accessibility of the major nutrients nitrogen (N) and phosphorus (P). These properties relate directly to the nature of the nutrient-poor recalcitrant litter produced by their host plants and through positive-feedback mechanisms that are reinforced by selective removal of labile nutrients by the mycorrhizas. We suggest that coevolution of these plant litter traits with mycorrhizal associations that are adapted to them has been one of the defining features of these ecosystems. Ericoid and ectomycorrhizal fungi have biochemical and physiological attributes that make them highly efficient at scavenging for organic sources of N and P in surface soil horizons. In so doing, they restrict supplies of these elements to the decomposer communities. Case studies involving exploitation of N and P in defined organic substrates are described. In both biomes the dominant plants depend upon the abilities of their fungal partners to recover nutrients, so the symbioses control nutrient cycles, productivity, species composition, and functioning of these ecosystems. It is in this context that the fungal symbionts are here considered to be drivers of nutritional processes in their respective biomes. Through their influences upon the quality of carbon residues mycorrhizal fungi must also affect the sink-source balance for this key element in soil. There is an urgent need for the evaluation of the relative contributions of symbiotic and saprotrophic components of the microflora to the processes of carbon storage and cycling in these biomes, particularly in the context of global climate change and impacts of anthropogenic pollutant N deposition.
Adaptation to temperate climates
Bradshaw, WE Zani, PA Holzapfel, CM
EVOLUTION 58:8 1748-1762
Only model organisms live in a world of endless summer. Fitness at temperate latitudes reflects the ability of organisms in nature to exploit the favorable season, to mitigate the effects of the unfavorable season, and to make the timely switch from one life style to the other. Herein, we define fitness as Ry, the year-long cohort replacement rate across all four seasons, of the mosquito, Wyeomyia smithii, reared in its natural microhabitat in processor-controlled environment rooms. First, we exposed cohorts of W. smithii, from southern, midlatitude, and northern populations (30-50degreesN) to southern and northern thermal years during which we factored out evolved differences in photoperiodic response. We found clear evidence of evolved differences in heat and cold tolerance among populations. Relative cold tolerance of northern populations became apparent when populations were stressed to the brink of extinction; relative heat tolerance of southern populations became apparent when the adverse effects of heat could accumulate over several generations. Second, we exposed southern, midlatitude, and northern populations to natural, midlatitude day lengths in a thermally benign midlatitude thermal year. We found that evolved differences in photoperiodic response (1) prevented the timely entry of southern populations into diapause resulting in a 74% decline in fitness, and (2) forced northern populations to endure a warm-season diapause resulting in an 88% decline in fitness. We argue that reciprocal transplants across latitudes in nature always confound the effects of the thermal and photic environment on fitness. Yet, to our knowledge, no one has previously held the thermal year constant while varying the photic year. This distinction is crucial in evaluating the potential impact of climate change. Because global warming in the Northern Hemisphere is proceeding faster at northern than at southern latitudes and because this change represents an amelioration of the thermal environment and a concomitant increase in the duration of the growing season, we conclude that there should be more rapid evolution of photoperiodic response than of thermal tolerance as a consequence of global warming among northern, temperate ectotherms.
Elevated CO2 alters birch resistance to Lagomorpha herbivores
Mattson, WJ Kuokkanen, K Niemela, P Julkunen-Tiitto, R Kellomaki, S Tahvanainen, J
GLOBAL CHANGE BIOLOGY 10:8 1402-1413
We studied the three-way interaction of elevated CO2, nitrogen (N), and temperature (T), and the two-way interaction of elevated CO2 and early-season defoliation on the secondary chemistry and resistance of Eurasian silver birch (Betula pendula) and North American paper birch (B. papyrifera) against the Eurasian hare (Lepus timidus) and the North American eastern cottontail rabbit (Sylvilagus floridanus), respectively. Elevated CO2 decreased the palatability of winter-dormant silver and paper birch stems to both hares and rabbits, respectively. But the effect on hares was only apparent at intermediate levels of N fertilization. Elevated T had no effect on palatability. The effects of elevated CO2, N, and T on levels of silver birch bark phenolics and terpenoids were dominated by two-way interactions between N and CO2, and N and T. Generally, however, N amendments elicited a parabolic response in carbon partitioning to most biosynthetic classes of silver birch phenolics (i.e. highest concentrations occurring at intermediate N). CO2 elevation was most enhancing at highest levels of N. On the other hand, T increases, more often than not, elicited reductions in phenolics, but especially so at the highest N level. In the case of B. papyrifera, elevated CO2 increased carbon partitioning to Folin-Denis stem and branch phenolics and condensed tannins. Early-season defoliation, on the other hand, had no effect on phenolics and tannins but lowered both N and energy levels of branches. Elevated CO2 substantially ameliorated the negative effects of severe defoliation on tree growth. These results support the hypothesis that continuing anthropogenic alterations of the atmosphere may trigger significant changes in plant phenotypic resistance to mammalian herbivores owing to an increasing net carbon balance between the highly vagile supply and demand capacities of plant carbon sources and sinks.
Determination of black carbon in natural organic matter by chemical oxidation and solid-state C-13 Nuclear Magnetic Resonance spectroscopy
Simpson, MJ Hatcher, PG
ORGANIC GEOCHEMISTRY 35:8 923-935
Black carbon is an important component of natural organic matter that may play a significant role in global climate change. However, the complexity of natural organic matter has resulted in a milieu of methods and accompanying black carbon values that make it difficult to delineate the proportion of black carbon in soil and sedimentary total carbon budgets, Here we report on a chemical oxidation method that removes lignin and then facilitates black carbon to be estimated from solid-state C-13 Nuclear Magnetic Resonance (NMR) spectroscopy. The resulting black carbon values are lower in comparison to those reported by other researchers but may be a more accurate method for estimating black carbon in a range of natural organic matter samples from different environments. (C) 2004 Elsevier Ltd. All rights reserved.
Simulated long-term changes in river discharge and soil moisture due to global warming
Manabe, S Milly, PCD Wetherald, R
HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES 49:4 625-642
By use of a coupled ocean-atmosphere-land model, this study explores the changes of water availability, as measured by river discharge and soil moisture, that could occur by the middle of the 21st century in response to combined increases of greenhouse gases and sulphate aerosols based upon the “IS92a” scenario. In addition, it presents the simulated change in water availability that might be realized in a few centuries in response to a quadrupling of CO2, concentration in the atmosphere. Averaging the results over extended periods, the radiatively forced changes, which are very similar between the two sets of experiments, were successfully extracted. The analysis indicates that the discharges from Arctic rivers such as the Mackenzie and Ob’ increase by up to 20% (of the pre-Industrial Period level) by the middle of the 21st century and by up to 40% or more in a few centuries. In the tropics, the discharges from the Amazonas and Ganga-Brahmaputra rivers increase substantially. However, the percentage changes in runoff from other tropical and many mid-latitude rivers are smaller, with both positive and negative signs. For soil moisture, the results of this study indicate reductions during much of the year in many semiarid regions of the world, such as the southwestern region of North America, the northeastern region of China, the Mediterranean coast of Europe, and the grasslands of Australia and Africa. As a percentage, the reduction is particularly large during the dry season. From middle to high latitudes of the Northern Hemisphere, soil moisture decreases in Summer but increases in winter.
The effects of infrared loading and water table on soil energy fluxes in northern peatlands
Noormets, A Chen, JQ Bridgham, SD Weltzin, JF Pastor, J Dewey, B LeMoine, J
ECOSYSTEMS 7:5 573-582
Increased radiative forcing is an inevitable part of global climate change, yet little is known of its potential effects on the energy fluxes in natural ecosystems. To simulate the conditions of global warming, we exposed peat monoliths (depth, 0.6 m; surface area, 2.1 m(2)) from a bog and fen in northern Minnesota, USA, to three infrared (IR) loading (ambient, +45, and +90 W m(-2)) and three water table (-16, -20, and -29 cm in bog and -1, -10 and -18 cm in fen) treatments, each replicated in three mesocosm plots. Net radiation (Rn) and soil energy fluxes at the top, bottom, and sides of the mesocosms were measured in 1999, 5 years after the treatments had begun. Soil heat flux (G) increased proportionately with IR loading, comprising about 3%-8% of Rn. In the fen, the effect of IR loading on G was modulated by water table depth, whereas in the bog it was not. Energy dissipation from the mesocosms occurred mainly via vertical exchange with air, as well as with deeper soil layers through the bottom of the mesocosms, whereas lateral fluxes were 10-20-fold smaller and independent of IR loading and water table depth. The exchange with deeper soil layers was sensitive to water table depth, in contrast to G, which responded primarily to IR loading. The qualitative responses in the bog and fen were similar, but the fen displayed wider seasonal variation and greater extremes in soil energy fluxes. The differences of G in the bog and fen are attributed to differences in the reflectance in the long waveband as a function of vegetation type, whereas the differences in soil heat storage may also depend on different soil properties and different water table depth at comparable treatments. These data suggest that the ecosystem-dependent controls over soil energy fluxes may provide an important constraint on biotic response to climate change.
Diurnal temperature range as an index of global climate change during the twentieth century
Braganza, K Karoly, DJ Arblaster, JM
GEOPHYSICAL RESEARCH LETTERS 31:13 -
The usefulness of global-average diurnal temperature range (DTR) as an index of climate change and variability is evaluated using observations and climate model simulations representing unforced climate variability and anthropogenic climate change. On decadal timescales, modelled and observed intrinsic variability of DTR compare well and are independent of variations in global mean temperature. Observed reductions in DTR over the last century are large and unlikely to be due to natural variability alone. Comparison of observed and anthropogenic-forced model changes in DTR over the last 50 years show much less reduction in DTR in the model simulations due to greater warming of maximum temperatures in the models than observed. This difference is likely attributed to increases in cloud cover that are observed over the same period and are absent in model simulations.
Seasonal thermal signatures of heat transfer by water exchange in an underground vault
Perrier, F Morat, P Yoshino, T Sano, O Utada, H Gensane, O Le Mouel, JL
GEOPHYSICAL JOURNAL INTERNATIONAL 158:1 372-384
The temperature of a 10-point vertical profile at the rock-atmosphere interface has been monitored since 2000 September in an underground vault at Aburatsubo, Japan, where resistivity variations have been reported in association with earthquakes. The non-ventilated vault is characterized by an annual temperature variation of about 1.2degreesC peak to peak, compatible with thermal diffusion in the surrounding tuff rock, and by a long-term temperature increase of about 0.1degreesC per year, possibly due to a local or global climate change. Owing to a careful relative calibration of the 10 thermistors used in this experiment, these data establish that the ceiling temperature is higher than the floor temperature by 0.04 to 0.28degreesC. Transient temperature variations are observed in association with human presence or with typhoons, with a characteristic spatial pattern revealing structural heterogeneity. Variations with periods ranging from 1 day to 1 week, with an amplitude two time larger and a phase advance on the floor with respect to the ceiling, are observed from November to May. Variations with periods larger than 1 week, with an amplitude two times smaller and a phase lag on the floor with respect to the ceiling, are observed from June to October. These cycles are linked to the sign of the seasonal heat flux. We propose an interpretation in which heat transfer in the cavity is dominated by diffusion of water vapour from June to October (heat flux downwards, summer regime) and by convective water transport from November to May (heat flux upwards, winter regime). The water flow inferred from this model can be used to predict the water saturation of the rock as a function of time. Because of a permanent radiative heat flux from top to bottom, the upward water flow in the winter regime is larger than the downward water flow in the summer regime, resulting in a slow depletion of water from the rock below the cavity. This unbalanced water flow could contribute to an observed steady secular increase of rock resistivity, and possibly also to the long-term temperature increase of 0.1degreesC per year. It is important to understand these processes in the context of underground geophysical observatories, underground waste storage and contaminant transport, as well as for the preservation of cultural items such as cave paintings.
Reconstructing the Pleistocene geography of the Aphelocoma jays (Corvidae)
Peterson, AT Martinez-Meyer, E Gonzalez-Salazar, C
DIVERSITY AND DISTRIBUTIONS 10:4 237-246
Understanding historical distributions of species and evolving lineages has been a topic of considerable interest, yet methods used to date have not provided detailed, quantitative distributional hypotheses. Here, we present a technique based on models of species’ ecological niches and Pleistocene climate reconstructions that provides such hypotheses, providing the example of reconstructions for the Aphelocoma jays. We demonstrate in general a greater degree than expected of stability in jay species’ distributional areas back through at least the most recent glaciation event, and that existing patterns of genetic differentiation may date to before the Late Pleistocene glaciations. More generally, the method offers the potential for reconstructing historical distributions of species or lineages, and providing a detailed geographic framework for addressing many biogeographic and systematic questions.
Scale-dependent climate signals drive breeding phenology of three seabird species
Frederiksen, M Harris, MP Daunt, F Rothery, P Wanless, S
GLOBAL CHANGE BIOLOGY 10:7 1214-1221
Breeding at the right time is essential for animals in seasonal climates in order to ensure that the energy demands of reproduction, particularly the nutritional requirements of growing young, coincide with peak food availability. Global climate change is likely to cause shifts in the timing of peak food availability, and in order to adapt successfully to current and future climate change, animals need to be able to adjust the time at which they initiate breeding. Many animals use environmental cues available before the breeding season to predict the seasonal peak in food availability and adjust their phenology accordingly. We tested the hypothesis that regulation of breeding onset should reflect the scale at which organisms perceive their environment by comparing phenology of three seabird species at a North Sea colony. As predicted, the phenology of two dispersive species, black-legged kittiwake (Rissa tridactyla) and common guillemot (Uria aalge), correlated with a large-scale environmental cue (the North Atlantic Oscillation), whereas a resident species, European shag (Phalacrocorax aristotelis), was more affected by local conditions (sea surface temperature) around the colony. Annual mean breeding success was lower in late years for European shags, but not for the other two species. Since correlations among climate patterns at different scales are likely to change in the future, these findings have important implications for how migratory animals can respond to future climate change.
Cadmium effects on mitochondrial function are enhanced by elevated temperatures in a marine poikilotherm, Crassostrea virginica Gmelin (Bivalvia : Ostreidae)
JOURNAL OF EXPERIMENTAL BIOLOGY 207:15 2639-2648
Marine intertidal mollusks, such as oysters, are exposed to multiple stressors in estuaries, including varying environmental temperature and levels of trace metals, which may interactively affect their physiology. In order to understand the combined effects of cadmium and elevated temperature on mitochondrial bioenergetics of marine mollusks, respiration rates and mitochondrial volume changes were studied in response to different cadmium levels (0-1000 mumol l(-1)) and temperatures (15, 25 and 35degreesC) in isolated mitochondria from the eastern oyster Crassostrea virginica acclimated at 15degreesC. It was found that both cadmium and temperature significantly affect mitochondrial function in oysters. Elevated temperature had a rate-enhancing effect on state 3 (ADP-timulated) and states 4 and 4+ (representative of proton leak) respiration, and the rate of temperature-dependent increase was higher for states 4 and 4+ than for state 3 respiration. Exposure of oyster mitochondria to 35degreesC resulted in a decreased respiratory control and phosphorylation efficiency (P/O ratio) compared to that of the-acclimation temperature (15degreesC), while an intermediate temperature (25degreesC) had no effect. Cadmium exposure did not lead to a significant volume change in oyster mitochondria in vitro. Low levels of cadmium (1-5 mumol l(-1)) stimulated the rate of proton leak in oyster mitochondria, while not affecting ADP-stimulated state 3 respiration. In contrast, higher cadmium levels (10-50 mumol l(-1)) had little or no effect on proton leak, but significantly inhibited state 3 respiration by 40-80% of the control rates. Elevated temperature increased sensitivity of oyster mitochondria to cadmium leading to an early inhibition of ADP-stimulated respiration and an onset of complete mitochondrial uncoupling at progressively lower cadmium concentrations with increasing temperature. Enhancement of cadmium effects by elevated temperatures suggests that oyster populations subjected to elevated temperatures due to seasonal warming or global climate change may become more susceptible to trace metal pollution, and vice versa.
Phasing of deglacial warming and laurentide ice sheet meltwater in the Gulf of Mexico
Flower, BP Hastings, DW Hill, HW Quinn, TM
GEOLOGY 32:7 597-600
Evidence is emerging that the tropical climate system played a major role in global climate change during the last deglaciation. However, existing studies show that deglacial warming was asynchronous across the tropical band, complicating the identification of causal mechanisms. The Orca Basin in the northern Gulf of Mexico is ideally located to record subtropical Atlantic sea-surface temperature (SST) warming in relation to mellwater input from the Laurentide Ice Sheet. Paired delta(18)O and Mg/Ca data on the planktonic foraminifer Globigerinoides ruber from core EN32-PC6 are used to separate deglacial changes in SST and delta(18)O of seawater. SST as calculated from Mg/Ca data increased by >3 degreesC from ca. 17.2 to 15.5 ka in association with Heinrich event I and was not in phase with Greenland air temperature. Subtracting temperature effects from delta(18)O values in G. ruber reveals two excursions representing Laurentide meltwater input to the Gulf of Mexico, one of >1.5parts per thousand from ca. 16.1 to 15.6 ka and a second major spike of >2.5parts per thousand from ca. 15.2 to 13.0 ka that encompassed meltwater pulse 1A and peaked ca. 13.8 ka during the Bolling-Allerod. Conversion to salinity through the use of a Laurentide meltwater end member of -25parts per thousand indicates that near-surface salinity decreased by 2parts per thousand-4parts per thousand during these spikes. These results suggest that Gulf of Mexico SST warming preceded peak Laurentide Ice Sheet decay and the Bolling-Allerod interval by >2 k.y. and that heat was retained in the subtropical Atlantic during Heinrich event 1, consistent with modulation of deglaciall climate by thermohaline circulation.
Dating the earliest lowland glaciation of eastern England: a pre-MIS 12 early Middle Pleistocene Happisburgh glaciation
Lee, JR Rose, J Hamblin, RJO Moorlock, BSP
QUATERNARY SCIENCE REVIEWS 23:14-15 1551-1566
This paper outlines the evidence for the Happisburgh Glaciation-the first Middle Pleistocene glaciation of lowland eastern England and the adjacent margins of the North Sea Basin. We propose that this glaciation occurred during a pre-Elsterian/Anglian (MIS 12) cold stage based on evidence of clasts of till, erratics and heavy minerals from the third youngest terrace of the ‘pre-glacial’ Bytham River in southern Norfolk. The heavy minerals show a progressive increase in glacially sourced materials from the bottom to the top of the Bytham River third terrace sediments. The till clasts are correlated with the extensive deposits of the Happisburgh Formation on the basis of their colour, heavy minerals and particle size properties. Thus, the Happisburgh Glaciation occurred during the accumulation of the Bytham River terrace deposits and prior to MIS 12, when the Bytham River system was destroyed by the Anglian glaciation. In the absence of any geochronology or robust biostratigraphy, the age of the Happisburgh Glaciation is estimated by the synchronisation of the pattern of large-scale river activity with patterns of Milankovitch-forced global climate change. On this basis, and assuming the British Ice Sheet acted in phase with global patterns of ice volume, the Happisburgh Glaciation is considered to have occurred during MIS 16 and be equivalent of the Don Glaciation of eastern Europe. (C) 2004 NERC. Published by Elsevier Ltd. All rights reserved.
Tedlar bag sampling technique for vertical profiling of carbon dioxide through the atmospheric boundary layer with high precision and accuracy
Schulz, K Jensen, ML Balsley, BB Davis, K Birks, JW
ENVIRONMENTAL SCIENCE & TECHNOLOGY 38:13 3683-3688
Carbon dioxide is the most important greenhouse gas other than water vapor, and its modulation by the biosphere is of fundamental importance to our understanding of global climate change. We have developed a new technique for vertical profiling of CO2 and meteorological parameters through the atmospheric boundary layer and well into the free troposphere. Vertical profiling of CO2 mixing ratios allows estimates of landscape-scale fluxes characteristic of similar to100 km(2) of an ecosystem. The method makes use of a powered parachute as a platform and a new Tedlar bag air sampling technique. Air samples are returned to the ground where measurements of CO2 mixing ratios are made with high precision (less than or equal to0.1%) and accuracy (less than or equal to0.1%) using a conventional nondispersive infrared analyzer. Laboratory studies are described that characterize the accuracy and precision of the bag sampling technique and that measure the diffusion coefficient of CO2 through the Tedlar bag wall. The technique has been applied in field studies in the proximity of two AmeriFlux sites, and results are compared with tower measurements of CO2.
Analysis of the conflict between omission and commission in low spatial resolution dichotomic thematic products: The Pareto Boundary
Boschetti, L Flasse, SP Brivio, PA
REMOTE SENSING OF ENVIRONMENT 91:3-4 280-292
During the last few years, the remote sensing community has been trying to address the need for global synthesis to support policy makers on issues such as deforestation or global climate change. Several global thematic products have been derived from large datasets of low-resolution remotely sensed data, the latter providing the best trade-off between spatial resolution, temporal resolution and cost. However, a standard procedure for the validation of such products has not been developed yet. This paper proposes a methodology, based on statistical indices derived from the widely used Error Matrix, to deal with the specific issue of the influence of the low spatial resolution of the dataset on the accuracy of the end-product, obtained with hard classification approaches. In order to analyse quantitatively the trade-off between omission and commission errors, we suggest the use of the ‘Pareto Boundary’, a method rooted in economics theory applied to decisions with multiple conflicting objectives. Starting from a high-resolution reference dataset, it is possible to determine the maximum user and producer’s accuracy values (i.e. minimum omission and commission errors) that could be attained jointly by a low-resolution map. The method has been developed for the specific case of diebotomic classifications and it has been adopted in the evaluation of burned area maps derived from SPOT-VGT with Landsat ETM+ reference data. The use of the Pareto Boundary can help to understand whether the limited accuracy of a low spatial resolution map is given by poor performance of the classification algorithm or by the low resolution of the remotely sensed data, which had been classified. (C) 2004 Elsevier Inc. All rights reserved.
Simulating the spatio-temporal variability of streamflow response to climate change scenarios in a mesoscale basin
Drogue, G Pfister, L Leviandier, T El Idrissi, A Iffly, JF Matgen, P Humbert, J Hoffmann, L
JOURNAL OF HYDROLOGY 293:1-4 255-269
A continuous rainfall-runoff simulation was performed to assess the potential effect of climate changes on the streamflow regimes and water resources of tributaries of the Alzette river basin extending over 1176 km(2), mainly in the Grand Duchy of Luxembourg. characterized by various hydrological patterns. Global climate change scenarios for the 2050 horizon, based on GCM projections from the KNMI and UKHI synoptic runs, were disaggregated into mesoscale daily PET and rainfall series. Seasonal expected PET changes were proportionally applied to present daily values, whereas future hyetographs were empirically constructed according to observed trends in rainfall time series for the study area. The various ways of applying the mesoscale rainfall scenarios exert a significant influence on the magnitude and spatial distribution of streamflow responses. The comparison of future and present hydrographs also shows that the impact of mesoscale climate change is extremely variable with regard to the considered hydrological variable. The spatial variability of streamflow responses is largely conditioned by climatic and physiographical characteristics of the sub-basins. The winter period is most affected by altered climate conditions and some sub-re ions appear to be particularly sensitive in terms of changes in low or high flows. (C) 2004 Elsevier B.V. All rights reserved.
Decadal-scale climate drivers for glacial dynamics in Glacier National Park, Montana, USA
Pederson, GT Fagre, DB Gray, ST Graumlich, LJ
GEOPHYSICAL RESEARCH LETTERS 31:12 -
Little Ice Age (14th-19th centuries A. D.) glacial maxima and 20th century retreat have been well documented in Glacier National Park, Montana, USA. However, the influence of regional and Pacific Basin driven climate variability on these events is poorly understood. We use tree-ring reconstructions of North Pacific surface temperature anomalies and summer drought as proxies for winter glacial accumulation and summer ablation, respectively, over the past three centuries. These records show that the 1850’s glacial maximum was likely produced by similar to70 yrs of cool/wet summers coupled with high snowpack. Post 1850, glacial retreat coincides with an extended period (>50 yr) of summer drought and low snowpack culminating in the exceptional events of 1917 to 1941 when retreat rates for some glaciers exceeded 100 m/yr. This research highlights potential local and ocean-based drivers of glacial dynamics, and difficulties in separating the effects of global climate change from regional expressions of decadal-scale climate variability.
Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: constraints from ODP Leg 204
Trehu, AM Long, PE Torres, ME Bohrmann, G Rack, FR Collett, TS Goldberg, DS Milkov, AV Riedel, M Schultheiss, P Bangs, NL Barr, SR Borowski, WS Claypool, GE Delwiche, ME Dickens, GR Gracia, E Guerin, G Holland, M Johnson, JE Lee, YJ Liu, CS Su, X Teichert, B Tomaru, H Vanneste, M Watanabe, M Weinberger, JL
EARTH AND PLANETARY SCIENCE LETTERS 222:3-4 845-862
Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, we sampled the gas hydrate stability zone (GHSZ) from the seafloor to its base in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30-40% of pore space or 20-26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs. Elsewhere, the average gas hydrate content of the sediments in the gas hydrate stability zone is generally < 2% of the pore space, although this estimate may increase by a factor of 2 when patchy zones of locally higher gas hydrate content are included in the calculation. These patchy zones are structurally and stratigraphically controlled, contain up to 20% hydrate in the pore space when averaged over zones similar to 10 m thick, and may occur in up to similar to 20% of the region imaged by 3D seismic data. This heterogeneous gas hydrate distribution is an important constraint on models of gas hydrate formation in marine sediments and the response of the sediments to tectonic and environmental change. Published by Elsevier B.V.
Soil carbon sequestration impacts on global climate change and food security
SCIENCE 304:5677 1623-1627
The carbon sink capacity of the world’s agricultural and degraded soils is 50 to 66% of the historic carbon loss of 42 to 78 gigatons of carbon. The rate of soil organic carbon sequestration with adoption of recommended technologies depends on soil texture and structure, rainfall, temperature, farming system, and soil management. Strategies to increase the soil carbon pool include soil restoration and woodland regeneration, no-till farming, cover crops, nutrient management, manuring and sludge application, improved grazing, water conservation and harvesting, efficient irrigation, agroforestry practices, and growing energy crops on spare lands. An increase of 1 ton of soil carbon pool of degraded cropland soils may increase crop yield by 20 to 40 kilograms per hectare (kg/ha) for wheat, 10 to 20 kg/ha for maize, and 0.5 to 1 kg/ha for cowpeas. As well as enhancing food security, carbon sequestration has the potential to offset fossil-fuel emissions by 0.4 to 1.2 gigatons of carbon per year, or 5 to 15% of the global fossil-fuel emissions.
Release of methane from a volcanic basin as a mechanism for initial Eocene global warming
Svensen, H Planke, S Malthe-Sorenssen, A Jamtveit, B Myklebust, R Eidem, TR Rey, SS
NATURE 429:6991 542-545
A 200,000-yr interval of extreme global warming marked the start of the Eocene epoch about 55 million years ago. Negative carbon-and oxygen-isotope excursions in marine and terrestrial sediments show that this event was linked to a massive and rapid (similar to10,000 yr) input of isotopically depleted carbon(1,2). It has been suggested previously that extensive melting of gas hydrates buried in marine sediments may represent the carbon source(3,4) and has caused the global climate change. Large-scale hydrate melting, however, requires a hitherto unknown triggering mechanism. Here we present evidence for the presence of thousands of hydrothermal vent complexes identified on seismic reflection profiles from the Voring and More basins in the Norwegian Sea. We propose that intrusion of voluminous mantle-derived melts in carbon-rich sedimentary strata in the northeast Atlantic may have caused an explosive release of methane-transported to the ocean or atmosphere through the vent complexes-close to the Palaeocene/Eocene boundary. Similar volcanic and metamorphic processes may explain climate events associated with other large igneous provinces such as the Siberian Traps (similar to250 million years ago) and the Karoo Igneous Province (similar to183 million years ago).
Changing global climate: Historical carbon and nitrogen budgets and projected responses of Ohio’s cropland ecosystems
Evrendilek, F Wali, MK
ECOSYSTEMS 7:4 381-392
As the evidence of global climate change continues to mount, its consequences for cropland productivity assume particular significance. Against the backdrop of past agricultural practices, simulation models offer a glimpse into the future, showing the effect of temperature changes on crop production. In this study, we first quantified the carbon (C) and nitrogen (N) budgets of Ohio’s cropland ecosystems using inventory yield data of corn for grain, oat, and all wheat for the period 1866-1996 and soybean for the period 1924-96. Then we explored the responses of Ohio’s continuous soybean croplands to changes in temperature, carbon dioxide (CO2) concentration, initial soil organic C and N (SOC-N) pools, soil texture, and management practices by developing a simple cropland ecosystem model (CEM) and performing a long-term sensitivity analysis. Finally, CEM simulations were evaluated against independent observations of SOC values (0-19 cm) averaged over 470 northwest Ohio sites between 1954 and 1987 under conventional tillage and rotations of corn-soybean-winter wheat by using the historical yield data (r(2) = 0.8). The C contents per hectare of crop harvests increased by 178% for oats, 300% for corn for grain, and 652% for all wheat between 1866 and 1996 and by 305% for soybean between 1924 and 1996. Ohio croplands acted as C-N sources, releasing average net ecosystem emissions (NEE), including the removal of harvested C-N, of 4,598 kg CO2 ha(-1) and 141 kg N ha(-1) in 1886 and 205 kg CO2 ha(-1) (except for the corn-for-grain cropland) and 39 kg N ha(-1) in 1996. The continuous corn croplands continued to become a C sink, sequestering 255 kg C ha(-1) in 1996. Results of the sensitivity analysis for Ohio’s continuous soybean croplands revealed that the SOC pool increased by 6.9% and decreased by 7.5% in response to a doubled CO2 concentration and a temperature increase of 2.8degreesC over 100 years, respectively. The sequestration potential of the SOC pool increased by 6.5% at a rate of 24.6 kg C ha(-1) y(-1) for the same period with finer soil texture (loam to silty clay loam). The shift from conventional to conservation residue practice led to an 11% increase in the steady-state SOC storage at a rate of 42 kg C ha(-1) y(-1) for 100 years.
Ecological issues and risk assessment in China
Fu, BJ Liu, GH Wang, XK Ouyang, ZY
INTERNATIONAL JOURNAL OF SUSTAINABLE DEVELOPMENT AND WORLD ECOLOGY 11:2 143-149
As a result of economic development and population explosion, global ecological environments have been severely disturbed and markedly changed. An ecological crisis involving desertification, soil erosion, degradation of land quality, loss of biodiversity and global climate change has been brought about all over the world. In order to manage ecosystems efficiently, it is necessary to assess ecological risk at multiple scales. Ecological risk is the probability that a region and/or site will experience defined ecological or environmental problems. In this paper, the ecological risks of soil erosion, desertification, and acid deposition have been assessed on a national scale according to natural and human factors, such as topography, soil, vegetation and climate. This assessment has provided very useful information for ecological environmental management in China.
Effects of global climate change on geographic distributions of vertebrates in North Queensland
ECOLOGICAL MODELLING 174:4 347-357
This paper assesses potential changes in the distributions of 12 endemic rainforest vertebrates of the Wet Tropics of Northeastern Australia in response to global warming predictions. It is based on projecting models of current geographic distribution to modelled future conditions taken from regional climate models. In comparing vertebrate species with different mobility, adaptation potential and distribution, consequences of global warming for elements of the regional biodiversity were investigated. The bioclimatic program. BIOCLIM, was used to determine the current climatic ranges and the potential changes in the distributions of the 12 species Linder four climate change scenarios for the year 2100. Results suggest that even species with currently wide climatic ranges may become vulnerable. Species distribution area decreased by more than 50% on average. Furthermore, the remaining predicted range decreased from an average of 90% under a conservative scenario, to about 40% under a less conservative scenario. These results show how sensitively some species could react to climate change and emphasise the need for rapid action on global warming for biodiversity conservation. (C) 2003 Published by Elsevier B.V.
Water scarcity under scenarios for global climate change and regional development in semiarid northeastern Brazil
de Araujo, JC Doll, D Guntner, A Krol, M Abreu, CBR Hauschild, M Mendiondo, EM
WATER INTERNATIONAL 29:2 209-220
The state of Ceara, located in semiarid northeastern Brazil, suffers under irregularly recurring droughts that go along with water scarcity. Structural policies to control and reduce water scarcity, as water supply and demand management, should be seen as long-term planning, and thus must consider climate change and regional development. To this end, the present research proposes a model-based global change scenario. Water stress is assessed for 184 municipalities in Ceara between 2001 and 2025. For this purpose, four global change scenarios are developed, considering both global climate change and the effects of development policies. Climatic, hydrological, and water use models are applied and a proposed index computed for identification of long-term water stress. Application of the methodology in the focus area shows that, if no effective intervention measures are taken, up to almost 60 percent of the municipalities of the state may suffer under long-term water scarcity by 2025. On average, municipalities in the state of Ceara have a water shortage probability for the next 25 years ranging from 9 percent to 20 percent annually, depending on the scenario. The 10 percent most stressed municipalities have a probability of over 80 percent annually of facing water scarcity in the scenario period (25 years). Results also show that a decentralized development policy can compensate for the possible severe effects of climatic trends on future water availability over the scenario period.
The impacts of human activities on the water-land environment of the Shiyang River basin, an arid region in northwest China
Kang, SZ Su, XL Tong, L Shi, PZ Yang, XY Abe, YK Du, TS Shen, QL Zhang, JH
HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES 49:3 413-427
The Shiyang River basin is a typical interior river basin that faces water shortage and environmental deterioration in the and northwest of China. Due to its arid climate, limited water resources and some inappropriate water-related human activities, the area has developed serious loss of vegetation, and gradual soil salinization and desertification, which have greatly impeded the sustainable development of agriculture and life in this region. In this paper, the impacts of human activities on the water-soil environment in Shiyang River basin are analysed in terms of precipitation, runoff in branches of the river, inflow into lower reaches, water conveyance efficiency of the canal system and irrigation water use efficiency in the field, replenishment and exploitation of groundwater resources, soil salinization, vegetation cover and the speed of desertification. The results show that human activities and global climate change have no significant influence on the precipitation, but the total annual runoff in eight branch rivers showed a significant decrease over the years. The proportion of water use in the upper and middle reaches compared to the lower reach was increased from 1:0.57 in the 1960s, to 1:0.27 in the 1970s and 1:0.09 in the 1990s. A reduction of about 74% in the river inflow to the lower reaches and a 15-m drop in the groundwater table have occurred during the last four decades. Strategies for improving the water-soil environment of the basin, such as the protection of the water resources of the Qilian Mountains, sustainable use of water resources, maintenance of the balance between land and water resources, development of water-saving agriculture, diverting of water from other rivers and control of soil desertification, are proposed. The objective of this paper is to provide guidelines for reconstruction of the sustainable water management and development of agriculture in this region.
Growth responses to ultraviolet-B radiation of two Carex species dominating an Argentinian fen ecosystem
Zaller, JG Searles, PS Caldwell, MM Flint, SD Scopel, AL Sala, OE
BASIC AND APPLIED ECOLOGY 5:2 153-162
Solar ultraviolet-B radiation (UV-B, 280-315 nm) in the Southern Hemisphere has been increasing over the last few decades due to seasonal stratospheric ozone depletion associated with the ‘ozone hole’ and a more general erosion of the stratospheric ozone layer. We studied the effect of UV-B radiation on growth responses of Carex curta and C. decidua, the two most dominant sedges in a fen ecosystem in Tierra del Fuego (Argentina) in field plots and growth chambers where U-V-B radiation was manipulated using different transparent plastic films that either transmitted or attenuated UV-B radiation. In the field, leaf and spike elongation of both species was unaffected by UV-B treatments in all four seasons studied (1997/98 through 2000/2001). Specific leaf areas (SLA) were only measured in the last two seasons and remained unaffected by UV-B for both species in the third field season. However, SLA decreased for C. curta in the fourth season but increased for C. decidua under near-ambient UV-B. Ecosystem specific root length was unaffected by UV-B. Although UV-B did not have a statistically significant effect on biomass production, there was a trend for a 15% higher production under near-ambient UV-B in the fourth year (P = 0.064). In the growth chambers, simulated ambient UV-B approximately equivalent to ambient UV-B in Tierra del Fuego stimulated seedling emergence of C. curta but reduced emergence of C. decidua; leaf elongation remained unaffected in both species. While plant morphology of C. curta remained unaffected by UV-B radiation, C. decid-ua had fewer tillers per plant, however tillers had more leaves and biomass under simulated ambient UV-B than under reduced UV-B radiation. The SLA of C. curta was unaffected by UV-B treatments; however, it was significantly lower for C. decidua under simulated ambient UV-B. Root morphology remained unaffected by UV-B for C. curta but roots of C. decidua were significantly thicker under simulated ambient UV-B. Taken collectively, our findings demonstrate that even moderate changes in UV-B radiation (e.g., corresponding to those expected with current stratospheric ozone depletion) may influence growth, morphology and biomass allocation in a species-specific manner for these native sedges in growth chambers and might also affect competitive relationships of these species in the field.
Ecophysiological response to severe drought in Pinus halepensis Mill. trees of two provenances
Atzmon, N Moshe, Y Schiller, G
PLANT ECOLOGY 171:1-2 15-22
As a result of predicted regional climatic changes the need to select for the more drought-tolerant genotypes (ecotypes) among Mediterranean conifers has become clear. Aleppo pine (Pinus halepensis Mill.) seems to be one of the most drought-tolerant pine species. Nevertheless, the existence of geographical trends in their genetic differentiation indicates potentially large differences in drought-tolerance among provenances. This assumption was verified by the finding of large variation among provenances in their internal water relations. Hence, the aim of this stud), was to compare the ecophysiological behaviour of several Aleppo pine provenances under contrasting climatic conditions. Growth parameters (height and diameter) and survival rate were measured in two provenance trials, one planted under sub-desertic conditions at the northern edge of the Negev desert, and the second under thermo-Mediterranean climatic conditions in the central coastal plains, Israel. Ecophysiological parameters such as: predawn needle water potential, sap flow in the xylem (i.e. transpiration), photosynthesis and water-use efficiency were measured in trees of selected provenances. The results suggest that it is not possible to predict provenance performance under harsh conditions from their performance under more favourable ones. Therefore, selection must be carried out under the exact conditions in which the trees from the resultant selection will be planted. The present study clearly emphasises the need for broad selection programs of P. halepensis.
Long-term tillage and crop rotation effects on microbial biomass and C and N mineralization in a Brazilian Oxisol
Balota, EL Colozzi, A Andrade, DS Dick, RP
SOIL & TILLAGE RESEARCH 77:2 137-145
Crop rotation and tillage impact microbial C dynamics, which are important for sequestering C to offset global climate change and to promote sustainable crop production. Little information is available for these processes in tropical/subtropical agroecosystems, which cover vast areas of terrestrial ecosystems. Consequently, a study of crop rotation in combination with no tillage (NT) and conventional tillage (CT) systems was conducted on an Oxisol (Typic Haplorthox) in an experiment established in 1976 at Londrina, Brazil. Soil samples were taken at 0-50, 50-100 and 100-200 mm depths in August 1997 and 1998 and evaluated for microbial biomass carbon (MBC) and mineralizable C and N. There were few differences due to crop rotation, however there were significant differences due to tillage. No tillage systems increased total C by 45%, microbial biomass by 83% and MBC:total C ratio by 23% at 0-50 mm depth over CT. C and N mineralization increased 74% with NT compared to CT systems for the 0-200 mm depth. Under NT, the metabolic quotient (CO2 evolved per unit of MBC) decreased by 32% averaged across soil depths, which suggests CT produced a microbial pool that was more metabolically active than under NT systems. These soil microbial properties were shown to be sensitive indicators of long-term tillage management under tropical conditions. (C) 2003 Elsevier B.V. All rights reserved.
Prepared for the GHG steamroller?
Kolwey, N Shepard, M
POWER 148:5 26-+
Global climate change is shaping up as a dominant environmental, business, and regulatory issue for the 21st century. Many utilities are formulating a strategy for reducing their greenhouse gas emissions-a handful have even inventoried and begun to cut them voluntarily-but quite a few remain in denial. The early birds are seeking a double competitive edge: reduced risk of not being ready to meet expected mandatory carbon caps and a “green” reputation in the marketplace.
Verification of magnetostratigraphic scales of miocene core section from Lake Baikal
Horiuchi, K Gol’dberg, EL Matsuzaki, H Kobayashi, K Shibata, Y
GEOLOGIYA I GEOFIZIKA 45:3 408-412
The dynamics of cosmogenic Be-10 contents in the BDP-96-1 (100 to 200 m) and BDP-98-2 (200 to 600 m) cores was used to test published magnetostratigraphic scales for the Miocene section and to time the core base. Only one of three alternative scales for the BDP-98 core tested against the Be-10 decay of T-1/2 = 1.5 myr showed a perfect consistency with the decay law. The basal age of the 600 m BDP-98 section was estimated at 8.4 myr.
Scenarios for sea level on the Finnish coast
Johansson, MM Kahma, KK Boman, H Launiainen, J
BOREAL ENVIRONMENT RESEARCH 9:2 153-166
The linkage between global climate change and sea level on the Finnish coast was studied. Scenarios were calculated for the long-term mean sea level in the future, based on the global change scenarios given by the Intergovernmental Panel on Climate Change. The effects of global mean sea level, local land uplift and the water balance of the Baltic Sea were taken into account. The effect of the water balance was estimated with the North Atlantic Oscillation (NAO) index. In most cases the rise in water level is expected to balance the land uplift in the Gulf of Finland, and the past declining trend of the relative sea level is not expected to continue. In the Gulf of Bothnia, the stronger land uplift rate still results in a fall of the relative mean sea level in the future. The uncertainties in the scenarios are large. Scenarios for the intra-annual variability of the sea level were constructed by extrapolating the 20th century trends of increasing variability.
Photosynthetic responses of Larrea tridentata to seasonal temperature extremes under elevated CO2
Naumburg, E Loik, ME Smith, SD
NEW PHYTOLOGIST 162:2 323-330
Elevated CO2 potentially decreases the effects of temperature stress on photosynthesis. Under both freezing and high temperatures previous studies have shown that elevated CO2 can particularly enhance photosynthetic rates, although results from freezing studies are more variable. Here we show gas exchange responses of Larrea tridentata to elevated CO2 over a 6-yr. period when temperature stress events may have had a significant effect on photosynthesis in the field. Nighttime freezing air temperatures decreased subsequent daytime photosynthetic rates, stomatal conductance, and the maximum yield of PSII similarly under ambient and elevated CO2. Further, we found no statistically significant relationship between leaf temperature and photosynthetic enhancement. Overall, the degree of photosynthetic enhancement under elevated CO2 was directly proportional to the response of stomatal conductance to CO2. Thus, elevated CO2 does not significantly affect apparent physiological responses of Larrea to temperature extremes. However, because of the tight relationship between stomatal conductance and photosynthetic enhancement, potential climate change effects on stomatal conductance will significantly influence Larrea performance in the future.
MSA in Beijing aerosol
Yuan, H Wang, Y Zhuang, GS
CHINESE SCIENCE BULLETIN 49:10 1020-1025
Methane sulphonate (MSA) and sulfate (SO42-) the main oxidation products of dimethyl sulfide (DMS), are the target of atmospheric chemistry study, as sulfate aerosol would have important impact on the global climate change. It is widely believed that DMS is mainly emitted from phytoplankton production in marine boundary layer (MBL), and MSA is usually used as the tracer of non-sea-salt sulfate (nss-SO42- ) in marine and coastal areas (MSA/SO42- = 1/18). Many observations of MSA were in marine and coastal aerosols.. To our surprise, MSA was frequently (>60%) detected in Beijing TSP, PM10, and PM2.5 aerosols, even in the samples collected during the dust storm period. The concentrations of MSA were higher than those measured in marine aerosols. Factor analysis, correlation analysis and meteorology analysis indicated that there was no obvious marine influence on Beijing aerosols. DMS from terrestrial emissions and dimethyl sulphoxide (DMSO) from industrial wastes could be the two possible precursors of MSA. Warm and low-pressure air masses and long time radiation were beneficial to the formation of MSA. Anthropogenic pollution from regional and local sources might be the dominant contributor to MSA in Beijing aerosol. This was the first report of MSA in aerosols collected in an inland site in China. This new finding would lead to the further study on the balance of sulfur in inland cities and its global biogeochemical cycle.
Superensemble prediction of regional precipitation over Korea
Kim, MK Kang, IS Park, CK Kim, KM
INTERNATIONAL JOURNAL OF CLIMATOLOGY 24:6 777-790
Seasonal precipitation at the decadal time scale is predicted using the downscaling super ensemble (DSE) method, which is developed by combining the superensemble procedure with a statistical downscaling method in this study. The multimodel data utilized are the long-term integration of six atmosphere-ocean general circulation models (AOGCMs) and the downscaling method is based on the singular value decomposition with the empirical orthogonal function (EOF) truncation to correct the systematic bias in the dynamic models. Interestingly, even though prediction skill in the training period is increased with increasing number of AOGCMs used, the skill is often decreased in the independent period. It is found that prediction skill in the independent period continues to rise when we use an optimal combination of predictors. The optimum combination used in constructing the superensemble model is the super-3 ensemble, which is a combination of three AOGCMs (CCCma, CSIRO, and NCAR) among the six AOGCMs used in this study. In general, the first four EOFs of sea-level pressure (SLP) in the super-3 ensemble are very similar to those of the observed SLP. The dynamic link between Korean winter precipitation and East Asian monsoon circulation in the super-3 ensemble is similar to that of the observed indicating that the super-3 ensemble realistically simulates the circulations in the East Asian monsoon region. The cross-validation for the prediction of the super-3 ensemble shows that the correlation skill score is about 0.49, which is significant at the 5% level. The results provide hope for regional climate prediction in decadal time-scales using superensemble methods together with statistical downscaling. Copyright (C) 2004 Royal Meteorological Society.
Climate change mitigation in Turkey
ENERGY SOURCES 26:6 563-573
One of the most contentious issues in the debate over global climate change is the perceived divide between interests and obligations of developed and developing countries. Equity demands that developed countries act first to reduce emissions. That principle is embedded in the 1992 United Nations Framework Convention on Climate Change and in the 1997 Kyoto Protocol, which sets binding emission targets for developed countries only. With the Protocol now likely to enter into force, the focus will turn increasingly to the question of developing country emissions. Turkey’s high rate of energy-related carbon emissions growth is expected to accelerate, with emissions climbing from 60 million tons in 2002 to almost 220 million tons in 2020. Carbon intensity in Turkey is higher than the western developed country average. Energy-intensive, inefficient industries remain under government control with soft budget constraints, contributing to undisciplined energy use. Planned industrial privatizations may close the oldest and most inefficient operations and modernize surviving ones. Elimination of energy price subsidies could stimulate energy conservation, reducing energy and emissions growth below current projections. This article reviews energy consumption and climate change mitigation in Turkey.
Water level variability and trends in Lake Constance in the light of the 1999 centennial flood
Johnk, KD Straile, D Ostendorp, W
LIMNOLOGICA 34:1-2 15-21
The extreme flood of Lake Constance in 1999 focused attention on the variability of annual lake levels. The year 1999 not only brought one of the highest floods of the last 180 years but also one of the earliest in the season. The 1999 extreme event was caused by heavy rainfall in the alpine and pre-alpine regions. The influence of precipitation in the two distinct regional catchments on lake level variations can be quantified by correlation analysis. The long-term variations in lake level and precipitation show similar patterns. This is seen through the use of spectral analysis, which gives similar bands of spectral densities for precipitation and lake level time series. It can be concluded from the comparison of these results with the analysis of climate change patterns in northern Europe, i.e. the index of the North Atlantic Oscillation, that the regional effects on lake level variations are more pronounced than those of global climate change.
Spatiotemporal influences of climate on altitudinal treeline in northern Patagonia
Daniels, LD Veblen, TT
ECOLOGY 85:5 1284-1296
Tree radial growth and seedling establishment of Nothofagus pumilio at alpine treeline near 40degrees S latitude in Chile and Argentina show time- and site-dependent relationships to interannual- and decadal-scale climate variation. Six treelines were sampled at two spatial scales corresponding to regional and local climates. A shift in climate from cool-wet to warm-dry conditions facilitated comparison of climate-vegetation relationships during two distinct periods: 1957-1976 and 1977-1996. For each treeline, tree radial growth and seedling establishment were correlated against monthly and seasonal temperature, precipitation, moisture availability, and two indices of El Ni (n) over tildeo-Southern Oscillation (ENSO): southern oscillation index (SOI) and sea surface temperature (SST). Four key aspects of climatic influences on N. pumilio radial growth and seedling establishment were as follows. (1) The relationship between krummholz radial growth and temperature variation was nonlinear. (2) Moisture availability was the dominant climatic factor influencing seedling establishment, although temperature-precipitation interactions resulted in variability among study areas. (3) Climate conditions that facilitated Nothofagus pumilio seedling establishment were distinct, and often opposite, from those that enhanced radial growth. (4) The relationships of radial growth and seedling demography with climate and ENSO differed among study areas and have been unstable over the past 40 years. Observed spatial and temporal instabilities in vegetation-climate relationships demonstrate the complexity of treeline dynamics in northern Patagonia under a changing climate. We conclude that a directional increase in temperature, as predicted by current global climate scenarios, will not necessarily result in an upslope expansion of the N. pumilio forests growing at altitudinal treeline in northern Patagonia.
Prediction of a global climate change on Jupiter
NATURE 428:6985 828-831
Jupiter’s atmosphere, as observed in the 1979 Voyager space craft images, is characterized by 12 zonal jet streams and about 80 vortices, the largest of which are the Great Red Spot and three White Ovals that had formed(1) in the 1930s. The Great Red Spot has been observed(2) continuously since 1665 and, given the dynamical similarities between the Great Red Spot and the White Ovals, the disappearance(3,4) of two White Ovals in 1997-2000 was unexpected. Their longevity and sudden demise has been explained(5) however, by the trapping of anticyclonic vortices in the troughs of Rossby waves, forcing them to merge. Here I propose that the disappearance of the White Ovals was not an isolated event, but part of a recurring climate cycle which will cause most of Jupiter’s vortices to disappear within the next decade. In my numerical simulations, the loss of the vortices results in a global temperature change of about 10 K, which destabilizes the atmosphere and thereby leads to the formation of new vortices. After formation, the large vortices are eroded by turbulence over a time of similar to60 years-consistent with observations of the White Ovals-until they disappear and the cycle begins again.
Public perceptions of unusually warm weather in the UK: impacts, responses and adaptations
Palutikof, JP Agnew, MD Hoar, MR
CLIMATE RESEARCH 26:1 43-59
Evidence of socio-economic sensitivity to climate variability is accumulating and is largely based on modelling studies. This paper examines the impacts of climate extremes (unusually hot summers and unusually warm winters) from the perspective of the perception of the general public. Postal surveys were conducted for 2 regions in the UK: (1) southern England and (2) central and southern Scotland. Information was gathered regarding attitudes to warm climate anomalies, the perceived risks and benefits of recent extremes, and the perceived potential risks and benefits of such anomalies becoming more common in the future. The impacts of climate extremes were assessed with regard to (1) the individual’s ‘everyday life’ and (2) the national ‘good’. The responses indicate a high level of awareness of the impacts of climate extremes and deep concerns about global warming tempered by an appreciation that there is potential for both positive and negative outcomes. For several issues, the perception of respondents from Scotland and England differed significantly. In particular, more English than Scottish residents judge unusually warm summers as having a severe negative impact on agriculture and air quality than do Scottish residents. We suggest that regional differences in climate could at least in part explain the apparent geographic differences in response. The results indicate both short-term and long-term adaptive and behavioural responses to a season of exceptional warmth and a willingness to implement further lifestyle adjustments for a hypothetical future in which such events become more common.
Appropriate measures for conservation of terrestrial carbon stocks - Analysis of trends of forest management in Southeast Asia
Phat, NK Knorr, W Kim, S
FOREST ECOLOGY AND MANAGEMENT 191:1-3 283-299
The 21st century has brought new challenges for forest management at a time when global climate change is becoming increasingly apparent. Additional to various goods and services being provided to human beings, forest ecosystems are a large store of terrestrial carbon and account for a-major part of the carbon exchange between the atmosphere and the land surface. Depending on the management regime, forests can thus be either a sink, or a source of atmospheric carbon. Southeast Asia or ASEAN comprises 10 countries of different cultures and political background. Rapid economic development and fast-growing population in the region have raised much concern over the use of natural resources, especially forest resources. This study aims at finding the appropriate measures for sustainable use and management of tropical forests on a long-term basis. Between 1990 and 2000, about 2.3 million ha of forest were cleared every year and lost to other forms of land use. In terms of carbon emissions, a net amount of approximately 465 million t per year were released to the atmosphere over the same period, which amounts to 29% of the global net carbon release from deforestation worldwide. This study provides an approach to analyzing the implications of alternative forest and land management options on forest carbon stocks. This is done in three steps: First, observed trends in land use are expressed in terms of a model in order to create a scenario for the period 1980-2050. Second, forest management practices and timber production rates are analyzed and three management scenarios are created: (1) continuing the current rate of exploitation, (2) management for long-term economic gains, and (3) climate-beneficial management. Third, the impact of the three scenarios on regional carbon storage is estimated on the basis of a carbon balance model. Comparing the additional rate of carbon sequestration of scenario (3) over scenario (2), and taking into account differing management costs, we also discuss a framework for industrialized countries to invest in carbon credits in the region in order to fulfil their commitments under present and future climate protection agreements. (C) 2004 Elsevier B.V. All rights reserved.
Risk and damage of southern pine beetle outbreaks under global climate change
FOREST ECOLOGY AND MANAGEMENT 191:1-3 61-71
This study, using the panel data modeling approach, investigates the relationships between climatic variables and southern pine beetle (SPB) (Dendroctonus frontalis Zimmermann) infestations and assesses the impact of global climate change on SPB infestation risk and damage. The panel data model alleviates possible collinearity among climatic variables, accounts for the effect of omitted or unobserved variables, and incorporates natural and human adaptation, thus representing a more robust approach to analyzing climate change impacts. SPB outbreaks in Louisiana and Texas appeared to move together; infestations in Alabama, Arkansas, Georgia, Florida, Mississippi, South Carolina, North Carolina, and Tennessee were highly correlated; and Virginia demonstrated its unique temporal pattern of SPB outbreaks. Salvage harvest was found to be helpful in lessening future infestation risk. Warmer winters and springs would positively contribute to SPB outbreaks with spring temperature showing a more severe and persistent impact than winter temperature; increases in fall temperature would ease SPB outbreaks; and summer temperature would have a mixed impact on SPB infestations. Compared to temperature, precipitation would have a much smaller impact on SPB infestations. While increases in the previous winter, spring, and fall precipitation would enhance SPB outbreak risk in the current year, a wetter summer would reduce infestations 3 years later. Global climate change induced by doubling atmospheric CO2 concentration would intensify SPB infestation risk by 2.5-5 times. If the changes in the area and productivity of southern pine forests due to climate change are accounted for, SPB would cause even more severe damage, 4-7.5 times higher than the current value of trees killed annually. (C) 2003 Elsevier B.V. All rights reserved.
Seedling establishment of a boreal tree species (Pinus sylvestris) at its southernmost distribution limit: consequences of being in a marginal Mediterranean habitat
Castro, J Zamora, R Hodar, JA Gomez, JM
JOURNAL OF ECOLOGY 92:2 266-277
1 We analyse the factors controlling seedling establishment of Scots pine at its southernmost geographical limit (southern Spain), by monitoring emergence, survival and growth for up to 4 years in the microhabitats to which seeds are dispersed. Naturally established seedlings were monitored in two mountain ranges, and experimental sowings were performed both in woodlands and in adjacent successional shrublands into which the forest could expand. 2 Emergence was high in all microhabitats, although it was highest under the canopy of shrubs. Overall survival was low, with c. 90% of seedlings dying in the first growing season (c. 98% after several growing seasons). Survival differed among microhabitats, being highest under shrubs and extremely low (or zero) under pines or in bare soil. 3 Seedling growth was the highest in areas of bare soil, intermediate under shrubs, and very low under pines. 4 Establishment under pines was prevented by both mortality and poor performance, and good performance cannot counteract high mortality in the open. Shrubs, however, acted as nurse plants, buffering summer drought without reducing radiation to levels critical for growth, and protecting seedlings from ungulate trampling, hail and frost heave. 5 Patterns of recruitment were similar for woodland stands and successional shrublands. In addition, patterns of survival for naturally established seedlings were similar to those of seedlings originating from experimental sowings. 6 Juveniles were positively associated with shrubs but negatively with bare soil or areas below pine canopies. The facilitative effect of shrubs on seedling survival therefore changes the spatial pattern of recruitment from that determined by germination. 7 Overall, processes controlling seedling establishment in these southern Scots pine forests differ sharply from those operating in its main distribution area. The comparison among contrasting geographical ranges may contribute to an understanding of the role of environmental conditions in the balance between competition and facilitation, and assist in forecasting plant regeneration responses to global climate change.
Impact of global warming and locally changing climate on tropical cloud forest bats
JOURNAL OF MAMMALOGY 85:2 237-244
Significant changes in local climate and correlated changes in non mammalian vertebrate populations have been documented in the Monteverde cloud forest in the Tileran Mountains of northern Costa Rica, leading to the prediction that corroborative changes should occur in bat populations. Habitat changes resulting from development for ecotourism, including a 19% increase in forest, might also be expected to impact bat populations. Analysis of data collected between 1973 and 1999 in Monteverde supports the hypothesis, although changes are less dramatic than those shown for birds, reptiles, and amphibians in earlier studies. Capture rates did not change significantly during the 27 year sample period, but relative species abundance increased, and at least 24 new species (of mostly lowland distribution) were recorded in the study area during the 1980s, 1990s, and through early 2002. These changes are likely a consequence of climatic change following global warming, forest clearing. and an increase in amount of secondary forest. This latter factor is a result of changes in land use due to development for tourism.
A decision matrix approach to evaluating the impacts of land-use activities undertaken to mitigate climate change - An editorial essay
Kueppers, LM Baer, P Harte, J Haya, B Koteen, LE Smith, ME
CLIMATIC CHANGE 63:3 247-257
Land-use activities that affect the global balance of greenhouse gases have been a topic of intense discussion during ongoing climate change treaty negotiations. Policy mechanisms that reward countries for implementing climatically beneficial land-use practices have been included in the Bonn and Marrakech agreements on implementation of the Kyoto Protocol. However some still fear that land-use projects focused narrowly on carbon gain will result in socioeconomic and environmental harm, and thus conflict with the explicit sustainable development objectives of the agreement. We propose a policy tool, in the form of a multi-attribute decision matrix, which can be used to evaluate potential and completed land-use projects for their climate, environmental and socioeconomic impacts simultaneously. Project evaluation using this tool makes tradeoffs explicit and allows identification of projects with multiple co-benefits for promotion ahead of others. Combined with appropriate public participation, accounting, and verification policies, a land-use activity decision matrix can help ensure that progressive land management practices are an effective part of the solution to global climate change.
Tree rings of Norway spruce (Picea abies (L.) Karsten) in Lithuania as drought indicators: dendroecological approach
POLISH JOURNAL OF ECOLOGY 52:2 201-210
Dendroecological research on the radial growth of Norway spruce in Lithuania during the 20(th) century has been conducted. Hypothesis of the study is following,: intensity of droughts during the 20(th) century is the main factor determining the state of spruce forests in Lithuania. Aim of the study was to estimate the impact of dry spring and summer climate conditions on Norway spruce during the 20(th) century with a respect to global climate change. Climate impact on the radial of spruce using multivariate regression techniques and detection of pointer years (i.e. years with narrow tree rings in the majority of trees) was investigated. The results show that for radial growth of spruce the most important factor is humid beginning of summer and that from four to six pointer years to droughts during the 20(th) century are attributed.
Effects of tree density and stand age on carbon allocation patterns in postfire lodgepole pine
Litton, CM Ryan, MG Knight, DH
ECOLOGICAL APPLICATIONS 14:2 460-475
Validating the components of the carbon (C) budget in forest ecosystems is essential for developing allocation rules that allow accurate predictions of C pools and fluxes. In addition, a better understanding of the effects of natural disturbances on C cycling is critical, particularly in light of alterations to disturbance regimes that may occur with global climate change. However, quantitative data about how postfire differences in ecosystem structure affect C allocation patterns are lacking. For this study, we examined how above- and belowground C pools, fluxes, and allocation patterns varied with fire-initiated differences in tree density and stand age in lodgepole pine stands in Yellowstone National Park of four forest types: low (< 1000 trees/ha), moderate (7000-40 000 trees/ha), and high tree densities (>50 000 trees/ha) in 13-year-old stands, and in similar to110-year-old mature stands. C pools in live biomass and detritus were estimated with allometric equations and direct sampling. Aboveground net primary productivity (ANPP) was estimated as aboveground biomass increment plus fine litterfall, and total belowground carbon allocation (TBCA) was estimated using a C balance approach. Our results indicate that the magnitude of C pools and fluxes varies greatly with fire-initiated differences in tree density and stand age. Coarse woody debris and mineral soil carbon accounted for the majority of total ecosystem C in young stands (91-99%), in contrast to mature stands where the largest amount of C was found in live biomass (64%). ANPP and TBCA increased with tree density (mean ANPP was 59, 122, and 156 g C.m(-2)-yr(-1), and TBCA was 68, 237, and 306 g C.m(-2).yr(-1) for low-, moderate-, and high-density young stands, respectively), and with stand age (ANPP was 218 g C.m(-2).yr(-1) and TBCA was 382 g C.m(-2).yr(-1) for 110-year-old stands). ANPP and TBCA were positively correlated, and both variables were well correlated with leaf area index. Notably, the ratio of TBCA to (TBCA + ANPP) remained remarkably constant (0.63-0.66) across extreme gradients of tree density and stand age, differing only slightly for the low-density young stands (0.54). These results suggest that C allocation patterns in a postfire lodgepole pine ecosystem are independent of tree density and stand age.
Leaf photosynthesis and carbohydrate dynamics of soybeans grown throughout their life-cycle under Free-Air Carbon dioxide Enrichment
Rogers, A Allen, DJ Davey, PA Morgan, PB Ainsworth, EA Bernacchi, CJ Cornic, G Dermody, O Dohleman, FG Heaton, EA Mahoney, J Zhu, XG Delucia, EH Ort, DR Long, SP
PLANT CELL AND ENVIRONMENT 27:4 449-458
A lower than theoretically expected increase in leaf photosynthesis with long-term elevation of carbon dioxide concentration ([CO2]) is often attributed to limitations in the capacity of the plant to utilize the additional photosynthate, possibly resulting from restrictions in rooting volume, nitrogen supply or genetic constraints. Field-grown, nitrogen-fixing soybean with indeterminate flowering might therefore be expected to escape these limitations. Soybean was grown from emergence to grain maturity in ambient air (372 mumol mol(-1)[CO2]) and in air enriched with CO2 (552 mumol mol(-1)[CO2]) using Free-Air CO2 Enrichment (FACE) technology. The diurnal courses of leaf CO2 uptake (A) and stomatal conductance (g(s)) for upper canopy leaves were followed throughout development from the appearance of the first true leaf to the completion of seed filling. Across the growing season the daily integrals of leaf photosynthetic CO2 uptake (A’) increased by 24.6% in elevated [CO2] and the average mid-day g(s) decreased by 21.9%. The increase in A’ was about half the 44.5% theoretical maximum increase calculated from Rubisco kinetics. There was no evidence that the stimulation of A was affected by time of day, as expected if elevated [CO2] led to a large accumulation of leaf carbohydrates towards the end of the photoperiod. In general, the proportion of assimilated carbon that accumulated in the leaf as non-structural carbohydrate over the photoperiod was small (< 10%) and independent of [CO2] treatment. By contrast to A’, daily integrals of PSII electron transport measured by modulated chlorophyll fluorescence were not significantly increased by elevated [CO2]. This indicates that A at elevated [CO2] in these field conditions was predominantly ribulose-1,5-bisphosphate (RubP) limited rather than Rubisco limited. There was no evidence of any loss of stimulation toward the end of the growing season; the largest stimulation of A’ occurred during late seed filling. The stimulation of photosynthesis was, however, transiently lost for a brief period just before seed fill. At this point, daytime accumulation of foliar carbohydrates was maximal, and the hexose:sucrose ratio in plants grown at elevated [CO2] was significantly larger than that in plants grown at current [CO2]. The results show that even for a crop lacking the constraints that have been considered to limit the responses of C-3 plants to rising [CO2] in the long term, the actual increase in A over the growing season is considerably less than the increase predicted from theory.
Assessing impacts of global warming on tropical cyclone tracks
Wu, LG Wang, B
JOURNAL OF CLIMATE 17:8 1686-1698
A new approach is proposed to assess the possible impacts of the global climate change on tropical cyclone (TC) tracks in the western North Pacific (WNP) basin. The idea is based on the premise that the future change of TC track characteristics is primarily determined by changes in large-scale environmental steering flows and in formation locations. It is demonstrated that the main characteristics of the current climatology of TC tracks can be derived from the climatological mean velocity field of TC motion by using a trajectory model. The climatological mean velocity of TC motion, composed of the large-scale steering and beta drift, is determined on each grid of the basin. The mean large-scale steering flow is computed from the NCEP-NCAR reanalysis for the current climate state. The mean beta drift is estimated from the best-track data by removing the steering flow. The derived mean beta drift agrees well with the results of previous observational and numerical studies in terms of its direction and magnitude. The approach is applied to assessing the potential impacts of global warming on TC tracks in the WNP. The possible changes in the large-scale steering flows are taken from the output wind fields of two Geophysical Fluid Dynamics Laboratory (GFDL) global warming experiments and possible changes in the TC formation locations are considered by shifting the formation locations as a whole. The GFDL experiments suggested that the changes in the future large-scale steering flows are dominated by the easterly anomalies in the Tropics and westerly anomalies in the midlatitudes with the enhanced northward component during the period of 2030-59. Based on the assessments using two different ways to reduce climate model biases, the prevailing TC tracks shift slightly southwestward during the period of 2000-29, but northeastward during the period of 2030-59. More TCs will take a recurving track and move northeastward during the period of 2030-59. The El Nino-like climate change predicted in many climate models can significantly enhance the track changes if the TC formation locations in the WNP shift eastward as a whole.
Global climate change and the emergence/re-emergence of infectious diseases
INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY 293: Suppl. 37 16-26
Variation in the incidence of vector-borne diseases is associated with extreme weather events and annual changes in weather conditions. Moreover, it is assumed that global warming might lead to an increase of infectious disease outbreaks. While a number of reports link disease outbreaks to single weather events, the El Nino/Southern Oscillation and other large-scale climate fluctuations, no report unequivocally associates vector-borne diseases with increased temperature and the environmental changes expected to accompany it. The complexity of not yet fully understood pathogen transmission dynamics with numerous variables might be an explanation of the problems in assessing the risk factors.
Modeling species’ geographic distributions for preliminary conservation assessments: an implementation with the spiny pocket mice (Heteromys) of Ecuador
Anderson, RP Martinez-Meyer, E
BIOLOGICAL CONSERVATION 116:2 167-179
GIS-based modeling of a species’ environmental requirements using known occurrence records can provide estimates of its distribution for conservation assessments when other data are lacking. We used collection records, environmental variables, maps of land cover and protected areas, and the Genetic Algorithm for Rule-Set Prediction (GARP) to estimate the historical, current, and protected ranges of the spiny pocket mice present in Ecuador (Heteromys australis and H. teleus). The results suggest that ca. 52-63% of the distributional areas of H. australis in the country are intact, but suitable habitat in protected areas represents only approximately 11-13% of the species’ historical range there. The distribution of H. teleus has been much more reduced, with only ca. 13-19% of its historical distribution still forested and an estimated 2-3% intact and falling in protected areas. Our work highlights critical areas for future fieldwork and demonstrates an integrated approach to estimating a species’ current distribution for preliminary conservation assessments. (C) 2003 Elsevier Ltd. All rights reserved.
Modelling climate change in West African Sahel rainfall (1931-90) as an artifact of changing station locations
Chappell, A Agnew, CT
INTERNATIONAL JOURNAL OF CLIMATOLOGY 24:5 547-554
Since the major droughts in the West African Sahel during the 1970s, it has been widely asserted that mean annual summer rainfall has declined since the late 1960s. Explanation of this persistent regional drying trend was important for famine early-warning and global climate models. However, the network of rainfall stations changed considerably during that recent period of desiccation. Furthermore, it was difficult to reconcile the calculation of a simple mean value for a region known to have a complex spatial and temporal rainfall pattern. A simple model separated the Sahel into ‘wet’ and ‘dry’ regions. This model was inverted against mean annual summer rainfall for the Sahel between 1931 and 1990. Model predictions were found to be insensitive to initial starting conditions. The optimized parameters explained 87% of the variation in observed mean annual summer rainfall. The model predicted the mean annual rainfall in the wet ‘coastal’ and dry ‘continental’ regions of the Sahel to be 973 mm and 142 mm respectively. Consequently, the predicted long-term mean annual summer rainfall was 558 mm, 15% greater than that of the observed long-term mean (417 mm). The mean annual summer rainfall for the region was corrected by removing the influence of changing station locations over the study period. No persistent decline was found in mean annual summer rainfall, which suggested that the perceived drying trend was an artifact of the crude statistical aggregation of the data and historical changes in the climate station networks. The absence of a decline in rainfall questioned the validity of the hypotheses and speculations for the causes of the drying trend in the region and its effects on global climate change. It also increased the likelihood that changes over time in other regional and global climate station networks have influenced the performance and interpretation of global climate models. Copyright (C) 2004 Royal Meteorological Society.
Inventory of the Maldives’ coral reefs using morphometrics generated from Landsat ETM+ imagery
Naseer, A Hatcher, BG
CORAL REEFS 23:1 161-168
In this study, we present exact measures of the number, area, and basic morphometric statistics for every single reef of the Maldivian archipelago, as derived from the interpretation of remotely sensed data collected by the Landsat-7 ETM+ earth-observing satellite sensor. We classified and mapped seven morphological attributes of reefs (six marine habitats and reef-top islands) to 30-m depth at 30x30 m spatial resolution (pixel size) for the entire archipelago. The total archipelagic area (all coral reef and lagoon habitats) of the 16 atolls, five oceanic faros, and four oceanic platform reefs which comprise the Maldives is 21,372.72+/-1,068.64 km(2) (approx. 20% of the Maldives’ Territorial Sea). A total of 2,041+/-10 distinct coral reef structures larger than 0.01 km(2) occur in the Maldives, covering an area of 4,493.85 km(2) (including enclosed reef lagoons and islands) to 30-m depth. Smaller areas of coral reef substratum cover another 19.29 km(2), bringing the total area of Maldivian coral reefs to 4,513.14+/-225.65 km(2). Shallow coral platforms thus occupy 21.1% of the total area of the archipelago (0.0052% of the EEZ area of the Maldives). Of these reefs, 538 are rim and oceanic reefs, covering 3,701.93 km(2) (82.5% of the total reef area), and 1,503 are patch reefs within the atoll lagoons, covering 791.92 km(2) (17.5% of the total reef area). Islands occupy only 5.1% of the total reef area. Mapping the Maldives’ coral reefs at high spatial resolution is only possible with remote sensing and spatial analysis technologies. These greatly reduce the large uncertainty around current estimates of reef area. Our accurate measure of total reef area is only 50.6% of the current best estimate, a result having significant implications for predictions of the Maldives’ reef productivity and response to global climate change. Here we present current best practice and compare the methods and measures with previous approaches.
Projecting large-scale area changes in land use and land cover for terrestrial carbon analyses
Alig, RJ Butler, BJ
ENVIRONMENTAL MANAGEMENT 33:4 443-456
One of the largest changes in US forest type areas over the last half-century has involved pine types in the South. The area of planted pine has increased more than 10-fold since 1950, mostly on private lands. Private landowners have responded to market incentives and government programs, including subsidized afforestation on marginal agricultural land. Timber harvest is a crucial disturbance affecting planted pine area, as other forest types are converted to planted pine after harvest. Conversely, however, many harvested pine plantations revert to other forest types, mainly due to passive regeneration behavior on nonindustrial private timberlands. We model land use and land cover changes as a basis for projecting future changes in planted pine area, to aid policy analysts concerned with mitigation activities for global climate change. Projections are prepared in two stages. Projected land use changes include deforestation due to pressures to develop rural land as the human population expands, which is a larger area than that converted from other rural lands (e.g., agriculture) to forestry. In the second stage, transitions among forest types are projected on land allocated to forestry. We consider reforestation, influences of timber harvest, and natural succession and disturbance processes. Baseline projections indicate a net increase of about 5.6 million ha in planted pine area in the South over the next 50 years, with a notable increase in sequestered carbon. Additional opportunities to expand pine plantation area warrant study of landowner behavior to aid in designing more effective incentives for inducing land use and land cover changes to help mitigate climate change and attain other goals.
Modification of growing-season surface temperature records in the northern Great Plains due to land-use transformation: Verification of modelling results and implication for global climate change
Mahmood, R Hubbard, KG Carlson, C
INTERNATIONAL JOURNAL OF CLIMATOLOGY 24:3 311-327
Land-use and land-cover change can modify near-surface atmospheric condition. Mesoscale modelling studies have shown that modification in land use affects near-surface soil moisture storage and energy balance. Such a study in the Great Plains showed that changes in land use from natural grass to irrigated agriculture enhanced soil water storage in the root zone and increased latent energy flux. This increase in latent energy flux would correspond to a decrease in sensible heat flux and, therefore, modify near-surface temperature records. To verify this deduction, we have investigated the changes in the historical near-surface temperature records in Nebraska, USA. We have analysed the long-term mean monthly maximum, minimum, and monthly mean air temperature data from five irrigated and five non-irrigated sites. The cooperative weather observation (coop) network is the source of the data. We have found that there is a clear trend in decreasing mean maximum and average temperature data for irrigated sites. For example, York, NE, reports that the mean maximum growing season temperature is decreasing at the rate -0.01 degreesC year(-1). The results from non-irrigated sites indicated an increasing trend for the same parameters. The data from Halsey, NE, indicate a +0.01 degreesC year(-1) increase in this century. In addition, we have conducted similar analyses of temperature data for the National Climatic Data Center’s Historical Climatic Network data set for the same locations. The results are similar to that obtained with the coop data set. Further investigation of dew-point temperature records for irrigated and non-irrigated sites also show an increasing and decreasing trend respectively. Therefore, we conclude that the land-use change in the Great Plains has modified near-surface temperature records. Copyright (C) 2004 Royal Meteorological Society.
Evaluation of an automatic sampling gas chromatographic-mass spectrometric instrument for continuous monitoring of trace anthropogenic gases
Maione, M Arduini, J Mangani, G Geniali, A
INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY 84:4 241-253
Continuous monitoring of the atmospheric volatile halogenated hydrocarbons is needed in light of the role played by these compounds in global climate change phenomena. The analytical methodology described in the following implies the use of a gas chromatographic-mass spectrometric system equipped with a sampling/pre-concentration unit, for the simultaneous and continuous analysis of a number of halogenated hydrocarbons present in the atmosphere at concentration levels ranging from a few to hundreds of part per trillion by volume. The optimization of the analytical procedure in terms of efficiency, linearity, and reproducibility is reported together with some of the results obtained in the frame of a monitoring activity carried out on a remote mountain station in central Italy.
Biomass energy technologies for rural infrastructure and village power - Opportunities and challenges in the context of global climate change concerns
Kishore, VVN Bhandari, PM Gupta, P
ENERGY POLICY 32:6 801-810
The potential and role of biomass resources in developing countries for addressing global climate change concerns are highlighted using India as a case study. Promotion of technologies, which use biomass more efficiently, is seen as a key strategy to integrate the concerns of both developing countries and developed countries. The role of various biomass technologies for improving rural infrastructure and village power is discussed in detail. A vision of establishing and running a chain of rural energy service companies, operating with a basket of devices and technologies, under the general provisions of CDM, is examined for commercialization and mainstrearning of biomass technologies which have achieved reasonable levels of maturity. (C) 2003 Elsevier Science Ltd. All rights reserved.
Tree diversity change in remaining primary mixed-broadleaved Korean pine forest under climate change and human activities
Chen, XW Li, BL
BIODIVERSITY AND CONSERVATION 13:3 563-577
Studying biodiversity change in existing typical ecosystems of the world under possible global climate change and local human activities is important for diversity conservation. An adapted forest dynamics model is used to simulate tree diversity change of the remaining primary mixed-broadleaved Korean pine forest (RPMKPF) in northeast China under global climate change and local human activities for the next 50 years. Human activities include logging, which removes all big trees (DBH>50 cm), removing all individuals of each single species and all species of each functional type (shade tolerant, shade intolerant and medium type tree species). As results for RPMKPF, the alpha index of tree diversity decreases under climate change, but it increases significantly under a combination of climate change and logging. Removing all individuals of each single species significantly affects the tree diversity of the ecosystem. After the removal of shade tolerant species, both alpha and beta(c) indices of tree diversity experience a significant change. The alpha index decreases significantly under climate change when shade intolerant or medium type tree species are removed, but the beta(c) index does not change significantly. The results of this study have implications for tree diversity management in RPMKPF under climate change and human activities.
Changes in the seasonal cycle in the Circumpolar Arctic, 1976-95: Temperature and precipitation
Whitfield, PH Hall, AW Cannon, AJ
ARCTIC 57:1 80-93
The Arctic is one region where the effects of global climate change are expected to be easy to observe. This study identifies regions in the circumpolar Arctic that have experienced similar changes in the seasonal cycle of temperature and precipitation over recent decades. Data from Arctic and northern nations have been compiled to form a new data set of over 1200 circumpolar Arctic climate stations. Changes in the seasonal cycle between two decades (1976-85 and 1986-95) are examined for the 247 temperature and 555 precipitation stations that meet specific completeness criteria. Inter-decadal shifts are analyzed using 11-day averages of daily mean temperature and 5-day averages of total daily precipitation. Examined at time-steps finer than annual or monthly means, climatic variations in the region are not consistent either through the seasons or across space. Some areas have demonstrated recent increases in temperature or precipitation, while others have displayed decreases in these elements. Many areas reveal climatic shifts in specific periods of the year that contrast markedly with the trends observed in other periods and other places.
Why Canada needs REUs
GEOSCIENCE CANADA 31:1 40-42
Problems of earth science involve not only questions of physical science and engineering, but also of the social sciences and humanities. As a fourth-year geo-environmental engineering student, I am increasingly concerned that issues of philosophy and public policy are being neglected in earth science classrooms. Realizing that my scholastic career was narrowing, I sought an opportunity to alleviate this concern and expand my horizon. This summer I participated in just such an opportunity: the Global Climate Change and Society Program, a Research Experience for Undergraduates (REU) sponsored by the National Science Foundation and held in Boulder, Colorado. Throughout the program, students were encouraged to collaborate with peers from around the country, exposed to an outstanding roster of guest speakers, and inspired to reap practical knowledge in disciplines outside their area of specialization. Canadian undergraduates in Earth science would greatly benefit from participating in educational programs of a similar nature. Canada’s closest analogue of the National Science Foundation, the Natural Sciences and Engineering Research Council, needs to expand its outreach programs and spearhead a campaign to develop Research Experiences for Undergraduates in Canada.
Energy security and global climate change mitigation
Huntington, HG Brown, SPA
ENERGY POLICY 32:6 715-718
Industrialized countries may reduce their costs of meeting carbon constraints if they penalize fuels not only on the basis of their carbon intensity but also on the basis of their import-export status. Simulations of these policies show that participating industrialized countries can reduce their costs and hence increase their willingness to participate. However, they will impose higher costs on the world, because the most carbon-intensive fuels will not be taxed most heavily. Such a bias creates a “how” inefficiency in addition to the “where” and “when” inefficiency created by current international agreements to control greenhouse gas emissions. Although countries have always had such incentives, these considerations must be more fully acknowledged in today’s energy markets, after September 2001. (C) 2003 Published by Elsevier Science Ltd.
Migration of Pacific Rim chum salmon on the high seas: insights from genetic data
Seeb, LW Crane, PA Kondzela, CM Wilmot, RL Urawa, S Varnavskaya, NV Seeb, JE
ENVIRONMENTAL BIOLOGY OF FISHES 69:1-4 21-36
Wild stocks of chum salmon, Oncorhynchus keta, have experienced recent declines in some areas of their range. Also, the release of hatchery chum salmon has escalated to nearly three billion fish annually. The decline of wild stocks and the unknown effects of hatchery fish combined with the uncertainty of future production caused by global climate change have renewed interest in the migratory patterns of chum salmon on the high seas. We studied the composition of high-seas mixtures of maturing and immature individuals using baseline data for 20 allozyme loci from 356 populations from throughout the Pacific Rim. Composition estimates were made from three time series. Two of these time series were from important coastal migratory corridors: the Shumagin Islands south of the Alaska Peninsula and the east coast of the Kamchatka Peninsula. The third was from chum salmon captured incidentally in the Bering Sea trawl fishery for walleye pollock. We also analyzed geographically dispersed collections of chum salmon captured in the month of July. The time series show dynamic changes in stock composition. The Shumagin Island corridor was used primarily by Northwest Alaskan and Asian populations in June; by the end of July stocks from the Alaska Peninsula and southern North America dominated the composition. The composition along the Kamchatka coast changed dramatically from primarily Russian stocks in May to primarily Japanese stocks in August; the previously undocumented presence of stocks from the Alaska Peninsula and Gulf of Alaska was also demonstrated. Immature chum salmon from throughout the Pacific Rim, including large proportions of southern North American stocks, contributed to the Bering Sea bycatch during the months of September and October. The migration routes of North American stocks is far more widespread than previously observed, and the Bering Sea is an important rearing area for maturing and immature chum salmon from throughout the species’ range.
Organic aerosol formation via sulphate cluster activation
Kulmala, M Kerminen, VM Anttila, T Laaksonen, A O’Dowd, CD
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 109:D4 -
[ 1] The formation of aerosols, and subsequent cloud condensation nuclei, remains one of the least understood atmospheric processes upon which global climate change critically depends. Under atmospheric conditions, the process of homogeneous nucleation (formation of stable clusters -1 nm in size), and their subsequent growth into new particles (>3 nm), determines the aerosol and cloud nuclei population, yet, hitherto, no theory has elucidated the new particle formation phenomenon in detail. In this study, we present a new theory which provides a mechanistic explanation for new particle formation via activation of stable inorganic clusters by organic vapors. The new nano-particle activation theory is analogous to Kohler theory which describes cloud formation in a supersaturated water vapor field but differs in that it describes the activation of inorganic stable nano-clusters into aerosol particles in a supersaturated organic vapor which initiates spontaneous and rapid growth of clusters. Inclusion of the new theory into aerosol formation models predicts that increases in organic vapor densities lead to even greater increases in particle production, which, in turn, will influence the global radiative cooling effect of atmospheric aerosols.
Impact of temperature on the arbuscular mycorrhizal (AM) symbiosis: growth responses of the host plant and its AM fungal partner
Heinemeyer, A Fitter, AH
JOURNAL OF EXPERIMENTAL BOTANY 55:396 525-534
The growth response of the hyphae of mycorrhizal fungi has been determined, both when plant and fungus together and when only the fungus was exposed to a temperature change. Two host plant species, Plantago lanceolata and Holcus lanatus, were grown separately in pots inoculated with the mycorrhizal fungus Glomus mosseae at 20/18degreesC (day/night); half of the pots were then transferred to 12/10degreesC. Plant and fungal growth were determined at six sequential destructive harvests. A second experiment investigated the direct effect of temperature on the length of the extra-radical mycelium (ERM) of three mycorrhizal fungal species. Growth boxes were divided in two equal compartments by a 20 mum mesh, allowing only the ERM and not roots to grow into a fungal compartment, which was either heated (+8degreesC) or kept at ambient temperature. ERM length (L-ERM) was determined on five sampling dates. Growth of H. lanatus was little affected by temperature, whereas growth of P. lanceolata increased with temperature, and both specific leaf area (SLA) and specific root length (SRL) increased independently of plant size. Percentage of colonized root (LRC) and L-ERM were positively correlated with temperature when in symbiosis with P. lanceolata, but differences in LRC were a function of plant biomass. Colonization was very low in H. lanatus roots and there was no significant temperature effect. In the fungal compartment L-ERM increased over time and was greatest for Glomus mosseae. Heating the fungal compartment significantly increased L-ERM in two of the three species but did not affect LRC. However, it significantly increased SRL of roots in the plant compartment, suggesting that the fungus plays a regulatory role in the growth dynamics of the symbiosis. These temperature responses have implications for modelling carbon dynamics under global climate change.
Spatial and temporal shifts in stable isotope values of the bottom-dwelling shrimp Nauticaris marionis at the sub-Antarctic archipelago
Pakhomov, EA McClelland, JW Bernard, K Kaehler, S Montoya, JP
MARINE BIOLOGY 144:2 317-325
Spatial and temporal dynamics of carbon and nitrogen stable isotope signatures of the bottom-dwelling caridean shrimp Nauticaris marionis were measured during April and May between 1984 and 2000 in the vicinity of Marion Island (the Prince Edward Islands, Southern Ocean). There was one trophic-level enrichment in bulk delta(15)N and delta(13)C signatures between small (<20 mm long) and large (>20 mm) specimens of N. marionis, suggesting distinct trophic differentiation among major shrimp size groups. Both delta(15)N and delta(13)C values of N. marionis increased with the depth, reflecting changes in their diet. There were no clear temporal trends in bulk delta(15)N signatures of N. marionis. However, compound-specific delta(15)N measurements of amino acids indicated that N. marionis from the inter-island realm occupied the trophic level of second order carnivores, while similarly sized shrimps in the near-shore realm were at the trophic level of first order carnivores. Compound-specific measurements also identified a change in the source of inorganic nitrogen at the base of the food web between the inter-island and near-shore realms. In contrast to the bulk delta(15)N values, a significant shift in bulk delta(13)C values of N. marionis was observed between 1984 and more recent years. This temporal change appears to be linked to changes in the overall productivity of the Prince Edward Island inter-island system, which could be linked to global climate change.
Greenhouse gas reduction and primary energy savings via adoption of a fuel cell hybrid plant in a hospital
Bizzarri, G Morini, GL
APPLIED THERMAL ENGINEERING 24:2-3 383-400
The Kyoto agreement, expressing great concern about global climate change, has stated emissions of greenhouse gases, especially CO2 from fossil fuel use, need to be reduced. According to this, existing plants have been required to cut emissions; moreover, there has been a greater emphasis on adopting efficient systems in order to reduce the energy losses. Among high efficiency technologies, fuel cells appear to be the most promising for their high efficiency and their very low environmental impact. This paper first reviews the state-of-the-art of fuel cells systems, then simulates the operation of a hybrid fuel cells plant in a “typical hospital” analysing how it could optimize the hospitals energetic requirements. Hospitals and sanitary structures are normally characterized by considerable energy demands not often suitable with resolute energy retrofit strategies. Both the considerable primary energy savings and the pollutant emissions reduction, achieved upgrading conventional systems to a fuel cell hybrid plant, have the potential to prompt national boards to support their business development, as long as they achieve a consolidated market penetration. (C) 2003 Elsevier Ltd. All rights reserved.
Effects of climate change on population persistence of desert-dwelling mountain sheep in California
Epps, CW McCullough, DR Wehausen, JD Bleich, VC Rechel, JL
CONSERVATION BIOLOGY 18:1 102-113
Metapopulations may be very sensitive to global climate change, particularly if temperature and precipitation change rapidly. We present an analysis of the role of climate and other factors in determining metapopulation structure based on presence and absence data. We compared existing and historical population distributions of desert bighorn sheep (Ovis canadensis) to determine whether regional climate patterns were correlated with local extinction. To examine all mountain ranges known to hold or to have held desert bighorn populations in California and score for variables describing climate, metapopulation dynamics, human impacts, and other environmental factors, we used a geographic information system (GIS) and paper maps. We used logistic regression and hierarchical partitioning to assess the relationship among these variables and the current status of each population (extinct or extant). Parameters related to climate-elevation, precipitation, and presence of dependable springs-were strongly correlated with population persistence in the twentieth century. Populations inhabiting lower, drier mountain ranges were more likely to go extinct. The presence of domestic sheep grazing allotments was negatively correlated with population persistence. We used conditional extinction probabilities generated by the logistic-regression model to rank native, naturally recolonized, and reintroduced populations by vulnerability to extinction under several climate-change scenarios. Thus risk of extinction in metapopulations can be evaluated for global-climate-change scenarios even when few demographic data are available.
Yellow-bellied marmots (Marmota flaviventris) hibernate socially
Blumstein, DT Im, S Nicodemus, A Zugmeyer, C
JOURNAL OF MAMMALOGY 85:1 25-29
Of 14 species of marmots (genus Marmota, Family Sciuridae), only 2, the woodchuck (M. monax) and yellow-bellied man-not (M. flaviventris), have not been reported to be obligate social hibernators. There is one published report of yellow-bellied man-not juveniles hibernating together at a subalpine site, and social hibernation was reported at a single high-alpine site. Solitary hibernation is expected in woodchucks because they do not share burrows during summer, but is unexpected in yellow-bellied marmots, a harem-polygynous species where females may share burrows and have extensive home-range overlap with female kin during summer. We documented emergence patterns in 13 matrilines to determine whether adult marmots hibernate socially. We found that adult males hibernated with 1 or more adult females, and mothers hibernated with their offspring. Therefore, we conclude that yellow-bellied marmots hibernate socially. There is, however, no evidence that suggests that yellow-bellied marmots receive social thermoregulatory benefits from social hibernation. Documenting social hibernation required us to quantify patterns of emergence from hibernation. Throughout our subalpine site, emergence appears to be getting earlier; a result consistent with a previous report based on 1 colony site and which suggests the effects of global climate change are affecting hibernation patterns.
Thinking aloud about trust: A protocol analysis of trust in risk management
RISK ANALYSIS 24:1 169-183
There are two general theories of trust in risk management. One, derived from normative considerations, claims that trust is based on universally applicable factors such as fairness and objectivity. According to the second, social-psychological theory, trust is based on agreement or similarity and is context specific. Although the first theory is normative, it also claims, along with the second, to be a descriptive account of how trust judgments are made. The present study was designed to test the adequacy of these two theories by using a think-aloud procedure to examine the thinking associated with trust judgments in an experimental simulation of a typical risk management context. Contrary to the universalist theory, results supported two hypotheses derived from the social-psychological theory. First, study participants-who read brief policy statements designed to address global climate change-based their trustjudgments on specific forms of agreement, ranging from agreement on the importance of the issue to agreement on values inferred from the policy statement. Second, the extent and depth of participants’ conscious information processing was negatively related to the level of trust. Disagreement and distrust generated more conscious consideration than agreement and trust. These results provide a more detailed understanding than previously available of how trust in risk management is based on local forms of agreement that vary across people, contexts, and time.
The global stationary wave response to climate change in a coupled GCM
Joseph, R Ting, MF Kushner, PJ
JOURNAL OF CLIMATE 17:3 540-556
The stationary wave response to global climate change in the Geophysical Fluid Dynamics Laboratory’s R30 coupled ocean-atmosphere GCM is studied. An ensemble of climate change simulations that use a standard prescription for time-dependent increases of greenhouse gas and sulfate aerosol concentrations is compared to a multiple-century control simulation with these constituents fixed at preindustrial levels. The primary response to climate change is to zonalize the atmospheric circulation, that is, to reduce the amplitude of the stationary waves in all seasons. This zonalization is particularly strong in the boreal summer over the Tropics. In January, changes in the stationary waves resemble that of an El Nino, and all months exhibit an El Nino-like increase of precipitation in the central tropical Pacific. The dynamics of the stationary wave changes are studied with a linear stationary wave model, which is shown to simulate the stationary wave response to climate change remarkably well. The linear model is used to decompose the response into parts associated with changes to the zonal-mean basic state and with changes to the zonally asymmetric “forcings” such as diabatic heating and transient eddy fluxes. The decomposition reveals that at least as much of the climate change response is accounted for by the change to the zonal-mean basic state as by the change to the zonally asymmetric forcings. For the January response in the Pacific-North American sector, it is also found that the diabatic heating forcing contribution dominates the climate change response but is significantly cancelled and phase shifted by the transient eddy forcing. The importance of the zonal mean and of the diabatic heating forcing contrasts strongly with previous linear stationary wave models of the El Nino, despite the similarity of the January stationary wave response to El Nino. In particular, in El Nino, changes to the zonal-mean circulation contribute little to the stationary wave response, and the transient eddy forcing dominates. The conclusions from the linear stationary wave model apparently contradict previous findings on the stationary wave response to climate change response in a coarse-resolution version of this model.
Isotopic estimates of new carbon inputs into litter and soils in a four-year climate change experiment with Douglas-fir
Hobbie, EA Johnson, MG Rygiewicz, PT Tingey, DT Olszyk, DM
PLANT AND SOIL 259:1-2 331-343
Because soil is a major reservoir of terrestrial carbon and a potential sink for atmospheric CO2, determining plant inputs to soil carbon is critical for understanding ecosystem carbon dynamics. We present a modified method to quantify the effects of global climate change on plant inputs of carbon to soil based on C-13:12C ratio (delta(13)C) analyses that accounts for isotopic fractionation between inputs and newly created soil carbon. In a four-year study, the effects of elevated CO2 and temperature were determined for reconstructed Douglas-fir ( Pseudotsuga mensiezii (Mirb.) Franco) ecosystems in which native soil of low nitrogen content was used. The d13C patterns in litter and mineral soil horizons were measured and compared to d13C patterns in live needles, fine roots, and coarse roots. From regression analyses, we calculated the isotopic enrichment in 13C of newly incorporated soil carbon relative to needle and root carbon at 4% and 2%, respectively. These enrichments must be considered when using shifts in soil d13C to calculate inputs of plant carbon into the soil, and are probably a major factor in the progressive enrichment in 13C with increasing depth in soil profiles. Relative to the total carbon in each layer, the proportion of new carbon from recent photosynthate in each soil layer was 13-15% in the A horizon, 7-9% in litter layers, and 4% in the B2 and C horizons. New carbon in the A horizon was estimated at 370 g C m(-2). Carbon concentrations and new carbon in A horizons were correlated (r(2) = 0.78, n = 12), but with a slope of 0.356, indicating that about 36% of net carbon accumulation in the A horizon was from inputs via roots, root exudates or mycorrhizal fungi and 64% of carbon was derived from surface litter decomposition. Under the nitrogen-limited growth conditions used in this study, neither elevated CO2 nor temperature affected soil carbon sequestration patterns.
Electrodynamic structure of charged dust clouds in the earth’s middle atmosphere
Scales, WA Ganguli, G
NEW JOURNAL OF PHYSICS 6: -
Noctilucent clouds (NLCs) and polar mesospheric summer echoes (PMSEs) are two phenomena at the forefront of near-earth space science. NLCs are high-altitude clouds in the earth’s mesosphere that are formed from visible aerosol particles. The occurrence rate of NLCs over time is believed to have profound implications on global climate change. NLCs are often associated with PMSEs which are strong 50 MHz-1.3 GHz radar echoes from mesospheric electron irregularities. Therefore, PMSEs may be an important remote-sensing diagnostic for the evolution of NLCs and the earth’s middle atmosphere in general. The electron irregularities that produce PMSEs are generally believed to result from charging of electrons onto subvisible aerosol irregularities, the source of which is currently a debated issue. Neutral air turbulence has long been considered a primary source of the irregularities. However, there are clearly fundamental characteristics of the irregularities in past and recent observations that cannot be explained by neutral air turbulence and most probably involve plasma processes. This work considers the latter mechanism and the possibility of production of aerosol irregularities in the boundary region between the charged aerosol layer and the background mesospheric plasma. First a model for investigating the electrodynamics of this boundary layer is described. This model indicates that plasma flows are expected to exist in the electrodynamic equilibrium. An initial assessment of the possible role of these plasma flows in producing irregularities that may ultimately result in PMSEs is provided.
Critically pressured free-gas reservoirs below gas-hydrate provinces
Hornbach, MJ Saffer, DM Holbrook, WS
NATURE 427:6970 142-144
Palaeoceanographic data have been used to suggest that methane hydrates play a significant role in global climate change. The mechanism by which methane is released during periods of global warming is, however, poorly understood(1). In particular, the size and role of the free-gas zone below gas-hydrate provinces remain relatively unconstrained, largely because the base of the free-gas zone is not a phase boundary and has thus defied systematic description. Here we evaluate the possibility that the maximum thickness of an interconnected free-gas zone is mechanically regulated by valving caused by fault slip in overlying sediments(2). Our results suggest that a critical gas column exists below most hydrate provinces in basin settings, implying that these provinces are poised for mechanical failure and are therefore highly sensitive to changes in ambient conditions(3). We estimate that the global free-gas reservoir may contain from one-sixth to two-thirds of the total methane trapped in hydrate(4). If gas accumulations are critically thick along passive continental slopes, we calculate that a 5 degreesC temperature increase at the sea floor could result in a release of similar to2,000 Gt of methane from the free-gas zone, offering a mechanism for rapid methane release during global warming events.
Could CO2-induced land-cover feedbacks alter near-shore upwelling regimes?
Diffenbaugh, NS Snyder, MA Sloan, LC
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 101:1 27-32
The response of marine and terrestrial environments to global changes in atmospheric carbon dioxide (CO2) concentrations will likely be governed by both responses to direct environmental forcing and responses to Earth-system feedbacks induced by that forcing. it has been proposed that anthropogenic greenhouse forcing will intensify coastal upwelling in eastern boundary current regions [Bakun, A. (1990) Science 247, 198-201]. Focusing on the California Current, we show that biophysical land-cover-atmosphere feedbacks induced by CO2 radiative forcing enhance the radiative effects Of CO2 on land-sea thermal contrast, resulting in changes in eastern boundary current total seasonal upwelling and upwelling seasonality. Specifically, relative to CO2 radiative forcing, land-cover-atmosphere feedbacks lead to a stronger increase in peak- and late-season near-shore upwelling in the northern limb of the California Current and a stronger decrease in peak- and late-season near-shore upwelling in the southern limb. Such changes will impact both marine and terrestrial communities [Bakun, A. (1990) Science 247,198-201; Soto, C. G. (2001) Rev. Fish Biol. Fish. 11, 181-195; and Agostini, V. N. & Bakun, A. (2002) Fish. Oceanogr. 11, 129-142], and these and other Earth-system feedbacks should be expected to play a substantial role in shaping the response of eastern boundary current regions to CO2 radiative forcing.
Observations on permafrost ground thermal regimes from Antarctica and the Italian Alps, and their relevance to global climate change
GLOBAL AND PLANETARY CHANGE 40:1-2 159-167
Active-layer monitoring and the permafrost thermal regime are key indicators of climate change. The results of 3 years (1997-1999) of active-layer monitoring at one high-mountain site (La Foppa, 46degrees28’ 42” N; 10degrees11’ 18” E, 2670 m a.s.l.) and at one Antarctic site (Boulder Clay, 74degrees44’ 45” S; 164degrees01’ 17” E, 205 m a.s.l) are presented. The initial analysis of a thermal profile in a borehole (100.3 m deep) within mountain permafrost at Stelvio (3000 m a.s.l., 46degrees30’ 59”N; 10degrees28’ 35” E) is also presented. At the alpine site, the active-layer thickness variations (between 193 and 229 cm) relate to both the snow cover and to the air temperature changes. By contrast, at the Antarctic site, there is a strong direct linkage only between air temperature fluctuations and active-layer variations. At the alpine (La Foppa) site, the relationship between climate and active-layer thickness is complicated by thermal offset that is almost negligible at both the Stelvio and Antarctic sites. The permafrost temperature profile at Stelvio site contains a climate signal suitable for paleoclimate reconstruction. The permafrost at this site has a mean annual ground surface temperature (MAGST) of - 1.9degreesC (during 1998/1999), an active layer of about 2.5 in thick and a total thickness of - 200 m. Analysis of the MAGST history, obtained by applying a simple heat conduction one-dimensional model, revealed the occurrence of a cold period from 1820 to 1940 followed by a warming period until 1978. Since the beginning of the 1980s, temperature dropped (less than 2degreesC) until the middle 1990s, when a new period of warming started. All these climatic changes fit well with the glacial fluctuations in the area and with other paleoclimatic information derived from different proxy data. (C) 2003 Elsevier B.V. All rights reserved.
Elevational dependence of projected hydrologic changes in the San Francisco Estuary and watershed
Knowles, N Cayan, DR
CLIMATIC CHANGE 62:1-3 319-336
California’s primary hydrologic system, the San Francisco Estuary and its upstream watershed, is vulnerable to the regional hydrologic consequences of projected global climate change. Previous work has shown that a projected warming would result in a reduction of snowpack storage leading to higher winter and lower spring-summer streamflows and increased spring-summer salinities in the estuary. The present work shows that these hydrologic changes exhibit a strong dependence on elevation, with the greatest loss of snowpack volume in the 1300 - 2700 m elevation range. Exploiting hydrologic and estuarine modeling capabilities to trace water as it moves through the system reveals that the shift of water in mid-elevations of the Sacramento river basin from snowmelt to rainfall runoff is the dominant cause of projected changes in estuarine inflows and salinity. Additionally, although spring-summer losses of estuarine inflows are balanced by winter gains, the losses have a stronger influence on salinity since longer spring-summer residence times allow the inflow changes to accumulate in the estuary. The changes in inflows sourced in the Sacramento River basin in approximately the 1300 - 2200 m elevation range thereby lead to a net increase in estuarine salinity under the projected warming. Such changes would impact ecosystems throughout the watershed and threaten to contaminate much of California’s freshwater supply.
Impact of soil warming and shading on colonization and community structure of arbuscular mycorrhizal fungi in roots of a native grassland community
Heinemeyer, A Ridgway, KP Edwards, EJ Benham, DG Young, JPW Fitter, AH
GLOBAL CHANGE BIOLOGY 10:1 52-64
Arbuscular mycorrhizal (AM) fungi have a major influence on the structure, responses and below-ground C allocation of plant communities. Our lack of understanding of the response of AM fungi to factors such as light and temperature is an obstacle to accurate prediction of the impact of global climate change on ecosystem functioning. In order to investigate this response, we divided a grassland site into 24 plots, each either unshaded or partly shaded with soil either unheated or heated by 3degreesC at 2 cm depth. In both short-term studies in spring and autumn, and in a 1-year-long study, we measured root length colonization (LRC) by AM and non-AM fungi. For selected root samples, DNA sequences were amplified by PCR with fungal-specific primers for part of the small sub-unit (SSU) rRNA gene. In spring, the total LRC increased over 6 weeks from 12% to 25%. Shading significantly reduced AM but increased non-AM fungal colonization, while soil warming had no effect. In the year-long study, colonization by AM fungi peaked in summer, whereas non-AM colonization peaked in autumn, when there was an additive effect of shading and soil warming that reduced AM but increased non-AM fungi. Stepwise regression revealed that light received within the 7 days prior to sampling was the most significant factor in determining AM LRC and that mean temperature was the most important influence on non-AM LRC. Loglinear analysis confirmed that there were no seasonal or treatment effects on the host plant community. Ten AM fungal sequence types were identified that clustered into two families of the Glomales, Glomaceae and Gigasporaceae. Three other sequence types were of non-AM fungi, all Ascomycotina. AM sequence types showed seasonal variation and shading impacts: loglinear regression analysis revealed changes in the AM fungal community with time, and a reduction of one Glomus sp. under shade, which corresponded to a decrease in the abundance of Trifolium repens. We suggest that further research investigating any impacts of climate change on ecosystem functioning must not only incorporate their natural AM fungal communities but should also focus on niche separation and community dynamics of AM fungi.
Long-term changes within the invertebrate and fish communities of the Upper Rhone River: effects of climatic factors
Daufresne, M Roger, MC Capra, H Lamouroux, N
GLOBAL CHANGE BIOLOGY 10:1 124-140
There is increasing evidence that the global climate change is already having measurable biological impacts. However, no study (based on actual data) has assessed the influence of the global warming on communities in rivers. We analyzed long-term series of fish (1979-1999) and invertebrate (1980-1999) data from the Upper Rhone River at Bugey to test the influence of climatic warming on both communities. Between the periods of 1979-1981 and 1997-1999, the average water temperature of the Upper Rhone River at Bugey has increased by about 1.5degreesC due to atmospheric warming. In the same period, several dams have been built from 12.5 to 85 km upstream of our study segment and a nuclear power plant has been built on it. Changes in the community structure were summarized using multivariate analysis. The variability of fish abundance was correlated with discharge and temperature during the reproduction period (April-June): low flows and high temperatures coincided with high fish abundance. Beyond abundance patterns, southern, thermophilic fish species (e.g. chub, and barbel) as well as downstream, thermophilic invertebrate taxa (e.g. Athricops, Potamopyrgus) progressively replaced northern, cold-water fish species (e.g. dace) and upstream, cold-water invertebrate taxa (e.g. Chloroperla, Protoneumura). These patterns were significantly correlated with thermal variables, suggesting that shifts were the consequences of climatic warming. All analyses were carried out using statistics appropriate for autocorrelated time series. Our results were consistent with previous studies dealing with relationships between fish or invertebrates and water temperature, and with predictions of the impact of climatic change on freshwater communities. The potential confounding factors (i.e. dams and the nuclear power plant) did not seem to influence the observed trends.
An inventory-based carbon budget for forest and woodland ecosystems of Turkey
JOURNAL OF ENVIRONMENTAL MONITORING 6:1 26-30
Environmental monitoring of national-level comparisons of CO2 emissions is needed to quantify sources and sinks of carbon ( C) in national ecosystems. In this study, a national forest inventory database was used to estimate the past and current pools and fluxes of C in deciduous and coniferous forest and woodland ecosystems (20.7 x 10(6) ha) of Turkey. Growing C stock was 12.63 t C ha(-1) in 1960 and 16.55 t C ha(-1) in 1995. Total C store in the whole live woody biomass was estimated at 22.77 t C ha(-1) in 1996. The total flux of C from the atmosphere into the forest and woodland ecosystems driven by primary productivity was about 1.46 t C ha(-1) (or 30.2 Mt C) in 1996. The estimated net release of C from the forest and woodland ecosystems of Turkey to the atmosphere was about 1.34 t C ha(-1) ( or 21.5 Mt C) in 1996. When C released was taken into account, net ecosystem sequestration (NES) resulted in 0.12 t C ha(-1) per year. Such analytical tools as national forest C budgets are needed to improve our preventive and mitigative strategies for dealing with global climate change.
Comparison of the Holocene and Eemian palaeoenvironments in the South Icelandic Basin: dinoflagellate cysts as proxies for the North Atlantic surface circulation
Eynaud, F Turon, JL Duprat, J
REVIEW OF PALAEOBOTANY AND PALYNOLOGY 128:1-2 55-79
A precise assessment of the hydrological changes in the northern Atlantic Ocean throughout the last climatic cycle stands as one of the key priorities for understanding the mechanisms of global climate change. A high resolution micropalaeontological study of a sediment core (MD95-2015) retrieved from the South Icelandic Basin, allows us to infer patterns of North Atlantic surface hydrological changes during the present (Holocene) and the ultimate (Marine Isotopic Stage 5) Interglacial periods. The downcore distribution of organic-walled dinoflagellate cysts (dinocysts) is used, in conjunction with additional proxies (sediment magnetic susceptibility, CaCO3, stables isotopes and planktic foraminifer assemblages) to identify climatic instabilities of various amplitudes. These events are mostly characterised by prominent changes in relative abundance of the dinocysts Spiniferites mirabilis and Operculodinium centrocarpum, whose maximum values are thought to trace sea-surface temperature peaks at the core site. Two hypsithermal periods are identified on this basis, between 126 and 120 kyr BP and from 9.2 to 5.7 cal kyr BP (similar to8-5 C-14 kyr BP), respectively. Some discrepancies between the micropalaeontological tracers used are discussed here in the light of their qualitative and quantitative (transfer functions) ecological interpretation. (C) 2003 Elsevier B.V. All rights reserved.
The value of museum collections for research and society
Suarez, AV Tsutsui, ND
BIOSCIENCE 54:1 66-74
Many museums and academic institutions maintain first-rate collections of biological materials, ranging from preserved whole organisms to DNA libraries and cell lines. These biological collections make innumerable contributions to science and society in areas as divergent as homeland security, public health and safety, monitoring of environmental change, and traditional taxonomy and systematics. Moreover, these collections save governments and taxpayers many millions of dollars each year by effectively guiding government spending, preventing catastrophic events in public health and safety, eliminating redundancy, and securing natural and agricultural resources. However, these contributions are widely underappreciated by the public and by policymakers, resulting in insufficient financial support for maintenance and improvement of biological collections.
N2O exchange within a soil and atmosphere profile in alpine grasslands on the Qinghai-Xizang Plateau
Pei, ZY Ouyang, H Zhou, CP Xu, XL
ACTA BOTANICA SINICA 46:1 20-28
Knowledge of nitrous oxide (N2O) exchanges through soils and atmosphere in various ecosystems has been of great importance in global climate change studies. However, the relative magnitude of surface and subsurface N2O production sources from the alpine grassland ecosystem is unclear. In the present study, the N2O concentration profile from 1.5 m in depth in soil to 32 m in height in air was measured from July 2000 to July 2001 in alpine grassland located in the permafrost area of the Qinghai-Xizang Plateau, which revealed that N2O concentrations had a distinct variation pattern both in air and in soil during the study period. Mean N2O concentrations in the atmosphere were significantly lower than those in the soil, which induced the N2O emission from the alpine steppe soil into the atmosphere. Mean flux of N2O in this alpine grassland experiment site was 0.05x10(-4) mumol(.)m(-2.)s(-1). But the variation in N2O emissions did not show any clear trends over the whole-year experiment in our study site. The highest N2O concentration was found at the depth of 1.5 m in the soil while the lowest N2O concentration occurred at the height of 8 m in the atmosphere. Mean N2O concentrations in the soil increased significantly with depth. This was the influence of increasing soil moistures, which induced the increasing denitrification potential with depth. The mean N2O concentrations at different heights in the air remained a more steady state because of the atmospheric negotiability. Seasonal variations of N2O concentrations showed significant correlations between the neighbor layers both in the soil and in the atmosphere. The seasonal variations of N2O concentrations at all horizons in the soil showed very clear patterns, with the highest concentrations occurring from the onset of frost to the freeze-thaw period and lowest concentrations occurring during the spring and the summer. Further analyses showed that the seasonal variations of N2O concentrations in the soil were hardly explained by soil temperatures at any depth. Temporally, atmospheric N2O concentrations at all heights exhibited almost the same seasonal pattern with the soil N2O variations, while soil is believed to be the predominant natural source of atmospheric N2O near the earth surface in this alpine grassland area. Also, a significant correlation was found between N2O emissions and soil N2O concentrations at 0.2 m in depth during the study period. This implied the variation of N2O concentrations in the soil surface horizon was the most direct driving force of N2O exchanges between the soil and the atmosphere. Soil atmospheric N2O at surface layers is the main source of N2O emissions from the soil surface to the atmosphere. Soil N2O concentrations at deeper layers were all significantly higher than those at surface layers, which indicated that N2O was diffused from the deeper layers to the surface layers in the soil, and finally was emitted to the atmosphere.
Changes in latitudes, changes in aptitudes: Nucella canaliculata (Mollusca : Gastropoda) is more stressed at its range edge
Sorte, CJB Hofmann, GE
MARINE ECOLOGY-PROGRESS SERIES 274: 263-268
A paradigm in biogeography is that organisms have ‘abundant center’ distributions, with abundances peaking at the range center and declining towards the range boundaries. One explanation for this pattern is that abundances are associated with organisms’ physiological stress levels and performances, with organisms experiencing more stress at the range edges. Here we explored whether the intertidal dogwhelk Nucella canaliculata was distributed in an ‘abundant center’ pattern. We addressed the role of stress in setting the species’ range limits. We determined dogwhelk abundances at range-center and range-edge sites and measured physiological stress levels by quantifying the 70 kDa heat-shock protein as a biochemical stress index. N. canaliculata was less abundant and more stressed at its southern range edge than at the range center, suggesting that populations at the range edge may be most impacted by global climate change.