|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.