Abstracts on Global Climate Change

Apr 2004

Prediction of a global climate change on Jupiter

Marcus, PS

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.

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Public perceptions of unusually warm weather in the UK: impacts, responses and adaptations

Palutikof, JP Agnew, MD Hoar, MR


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.

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Appropriate measures for conservation of terrestrial carbon stocks - Analysis of trends of forest management in Southeast Asia

Phat, NK Knorr, W Kim, S


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.

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Risk and damage of southern pine beetle outbreaks under global climate change

Gan, JB


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.

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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


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.

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Impact of global warming and locally changing climate on tropical cloud forest bats

LaVal, RK


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.

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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.

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Tree rings of Norway spruce (Picea abies (L.) Karsten) in Lithuania as drought indicators: dendroecological approach

Vitas, A


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.

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Effects of tree density and stand age on carbon allocation patterns in postfire lodgepole pine

Litton, CM Ryan, MG Knight, DH


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.

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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


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.

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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.

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Global climate change and the emergence/re-emergence of infectious diseases

Zell, R


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.

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Modeling species’ geographic distributions for preliminary conservation assessments: an implementation with the spiny pocket mice (Heteromys) of Ecuador

Anderson, RP Martinez-Meyer, E


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.

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Modelling climate change in West African Sahel rainfall (1931-90) as an artifact of changing station locations

Chappell, A Agnew, CT


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.

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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.

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Projecting large-scale area changes in land use and land cover for terrestrial carbon analyses

Alig, RJ Butler, BJ


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.

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