Global Change Bibliography - Article Abstracts



Adams, Richard M., Ronald A. Fleming, Ching-Chang Chang, Bruce A. McCarl, and Cynthia Rosenzweig
"A Reassessment of the Economic Effects of Global Climate Change on U.S. Agriculture"

This study uses recent GCM forecasts, improved plant science and water supply data and refined economic modeling capabilities to reassess the economic consequences of long-term climate change on U.S. agriculture. Changes in crop yields, crop water demand and irrigation water arising from climate change result in changes in economic welfare. Economic consequences of the three GCM scenarios are mixed; GISS and GFDL-QFlux result in aggregate economic gain, UKMO implies. losses As in previous studies, the yield enhancing effects of atmospheric CO2 are an important determinant of potential economic consequences. Inclusion of changes in world food production and associated export changes generally have a positive affect on U.S. agriculture. As with previous studies, the magnitude of economic effects estimated here are a small percentage of U.S. agricultural value.


Anderson, Glen D.
"Joint Implementation Projects to Reduce Greenhouse Gas Emissions: Prospects for Poland"

Countries throughout the world have become increasingly concerned about the buildup of greenhouse gases in the atmosphere and the potential ramifications for a net increase in surface temperatures. Signatories to the Framework Convention on Climate Change (FCCC), including Poland, have made a commitment to stabilize greenhouse gases (GHGs) to their 1990 (1988 for Poland) levels by the year 2000. Even if these countries are successful in stabilizing their emissions, many experts believe that GHGs must be reduced even further. Negotiations on additional reductions in GHG emissions in the next century are now underway. Joint Implementation (JI) refers to a cooperative project between a donor (Annex I country under the FCCC) who provides funds or equipment to reduce GHGs in the territory of the host country. JI projects are attractive to donors because they provide the potential to achieve emission reductions at a lower cost/ton than investments in GHG reductions in their own country. To make JI attractive, donors need to receive credit for GHG reductions in the host country. Poland will most likely be a host country if it participates in JI projects because the cost/ton of GHG reductions in Poland will probably be below the costs of options in donor. countries The paper examines a range of issues that Poland would need to address to more effectively evaluate, implement, and monitor JI projects. Particular attention in the paper is focused on JI criteria, options for organizing a JI Secretariat, and legal issues related to negotiations and contracts the Government of Poland would undertake with donor countries and JI implementors, respectively.


Annenkov, Vladimir V.
"Problems and Approaches in Historical Geography of Global Environmental Change"

The paper introduces some problems and approaches for studies of environmental changes over the last millennia, centuries and decades, when human impact on environments became comparable by magnitude with action of the cosmic and telluric forces. Historical geography integrates the historical typology of human impact with studies on anthropogenic evolution of landscapes and geobiosphere functioning. These heterogeneous aspects of the Earth System transformation are combined around the notion of Noosphere as the new stage in Biosphere evolution under human impact.


Baker, William L. and Yunming Cai
"The r.le Programs for Multiscale Analysis of Landscape Structure Using the GRASS Geographical Information System"

Geographical information systems (GIS) are well suited to the spatial analysis of landscape data, but generally lack programs for calculating traditional measures of landscape structure (e.g., fractal dimension). Stand-alone programs for calculating landscape structure measures do exist, but these programs do not enable the user to take advantage of GIS facilities for manipulating and analyzing landscape data. Moreover, these programs lack capabilities for analysis with sampling areas of different size (multiscale analysis) and also lack some needed measures of landscape structure (e.g., texture).


Balling, Robert C.
"The Global Temperature Data"

When all of the greenhouse gases are expressed in CO2 equivalents, we find that over the past 100 years, equivalent CO2 values have increased by 40%. Over this period, the temperature of the planet appears to have increased by 0.5%°C; however, much of this warming may be explained by a variety of non-greenhouse. factors In addition, fully 75% of the global warming of the past century occurred before the end of the Second World War, long before most of the trace gases were added to the atmosphere. Furthermore, the celebrated warming of the 1980s and early 1990s is seriously challenged by recent satellite-based global temperature measurements that show essentially no warming at all. In an effort to explain these findings, climate scientists are pointing to the cooling effects of human-induced increases of atmospheric SO2. The bottom line is simple--despite a public perspective to the contrary, the global temperature record provides little support for the catastrophic view of the greenhouse effect.


Bhaskaran, B., J.F.B. Mitchell, J.R. Lavery, and M. Lal
"Climatic Response of the Indian Subcontinent to Doubled CO2 Concentrations"

Results from the United Kingdom Meteorological Office (UKMO) coupled climate model have been analysed over the Indian subcontinent in order to validate the model's performance and to assess the changes in climate and its variability in a simulation with a 1 percent increase per year in CO2 (compound).


Bilsborrow, Richard and H.W.O. Okoth Ogendo
"Population-driven Changes in Land Use in Developing Countries"

This paper shows that demographic processes influence land degradation through the intervening variables of land use. A proper understanding of the effects of population growth and redistribution on deforestation, soil erosion,. etc , requires examining changes in land-use patterns over time. A conceptual framework is proposed, wherein these changes are seen to be manifest in various forms, depending on natural resources and institutional factors, including changes in land-tenure arrangements, land intensification, and land. extensification Cross-country data on demographic trends, changes in land use and environmental degradation are presented, to provide an overview for Latin American and sub-Saharan Africa. Specific linkages are examined and case studies for Guatemala and Kenya are presented.


Binkley, Clark S. and G. Cornelis van Kooten
"Integrating Climatic Change and Forests: Economic and Ecologic Assessments"

Effective policies for dealing with anticipated climatic changes must reflect the two-way interactions between climate, forests and society. Considerable analysis has focused on one aspect of forests - timber production- at a local and regional scale, but no fully integrated global studies have been conducted. The appropriate ecological and economic model appear to be available to do so. Nontimber aspects of forests dominate the social values provided by many forests, especially remote or unmanaged lands where the impacts of climatic change are apt to be most significant. Policy questions related to these issues and lands are much less well understood. Policy options related to afforestation are well studied, but other ways the forest sector can help ameliorate climatic change merit more extensive analysis. Promising possibilities include carbon taxes to influence the management of extant forests, and materials policies to lengthen the life of wood products or to encourage the substitution of CO2-fixing wood products for ones manufactured from less benign materials.


Bond, Gerard C. and Rusty Lotti
"Iceberg Discharges into the North Atlantic on Millennial Time Scales During the Last Glaciation"

High-resolution studies of North Atlantic deep sea cores demonstrate that prominent increases in iceberg calving recurred at intervals of 2000 to 3000 years, much more frequently than the 7000- to 10,000-year pacing of massive ice discharges associated with Heinrich events. The calving cycles correlate with warm-cold oscillations, called Dansgaard-Oeschger events, in Greenland ice cores. Each cycle records synchronous discharges of ice from different sources, and the cycles are decoupled from sea-surface temperatures. These findings point to a mechanism operating within the atmosphere that caused rapid oscillations in air temperatures above Greenland and in calving from more than one ice sheet.


Bowes, Michael D. and Roger A. Sedjo
"Impacts and Responses to Climate Change in Forests of the MINK Region"

The adaptability of forests in the U.S. midwest to a changing climate is. assessed The forests of Missouri are simulated with a "forest-gap" model, a stochastic model of the annual growth and mortality of trees within mixed species forest plots. The development of representative forest plots under an analog climate like that of the 1930s is compared to development under baseline climate. conditions With no management response, average forest biomass in the region decline by 11% within ten years, primarily due to moisture-stress induced. mortality Longer term declines in forest productivity on the order of 30% are. simulated A variety of possible management responses through planting or harvesting practices were evaluated. None of these adaptations appear to be practical, although the salvage harvest of stressed trees would offset the economic losses associated with early mortality. An investigation of anticipated trends in the broader forest products sector suggests that opportunities for further adaptation to offset the decline in primary productivity of this region's forest are quite limited. However, a shift to wood powered electrical generation in the region might justify a level of management that would allow some adaptation to the analog climate change.


Bowes, Michael D. and Pierre R. Crosson
"Consequences of Climate Change for the MINK Economy: Impacts and Responses"

The impacts of climate change on the agricultural, energy, forestry, and water sectors of MINK would reverberate negatively throughout the regional. economy Allowing for sectoral adjustments to the new climate, however, the decline in regional income and production would not likely exceed 1-2%. The largest economy-wide impacts would be by way of the agricultural and water. sectors The impacts by way of forestry and energy would be negligible, unless the nation adopts a program of massive reforestation to capture CO2, which would positively affect the regional economy.


Bryson, Reid A.
"On Integrating Climate Change and Culture Change Studies"

In the last few decades, advances in understanding and modeling climate have paralleled the growth of an impressive log of radiocarbon dates and quantitative analyses of climatic indicators including pollen, tree rings, and lake levels. At the same time, archeological research has given us an impressive assemblage of cultural information. We also have the tools for sorting out the diverse sources of variance in our datasets. The time has come to begin to integrate these lines of scientific endeavor to produce a mutually coherent picture of at least one of the mechanisms that have affected the history of humankind, and one that undoubtedly will affect the future as well.


Burton, P.J. and S.G. Cumming
"Potential Effects of Climatic Change on Some Western Canadian Forests, Based on Phenological Enhancements to a Patch Model of Forest Succession"

We enhanced the forest patch model, Zelig, to explore the implications of 2XCO2 climate change scenarios on several forest regions in British Columbia and Alberta, Canada. In addition to the processes and phenomena commonly represented in individual-based models of forest stand dynamics, we added some species specific phenology and site-specific frost events. The consideration of bud-break heat sum requirements, growing season limits and chilling requirements for the induction of dormancy and cold hardiness slightly improved the ability of Zelig to predict the present composition of B.C. forests. Simulations of the predicted effects of future climatic regimes (based on the averaged predictions of four general circulation models) include some major shifts in equilibrial forest composition and productivity. Lowland temperate coastal forests are predicted to be severely stressed because indigenous species will no longer have their winter chilling requirements met. High-elevation coastal forests are expected to increase in productivity, while interior subalpine forests are expected to remain stable in productivity but will gradually be replaced by species currently characteristic of lower elevations. Dry, interior low-elevation forests in southern B.C. are likely to persist relatively unchanged, while wet interior forests are expected to support dramatic increases in yield, primarily by western. hemlock Northern interior sub-boreal forests are likewise expected to increase in productivity through enhanced growth of lodgepole pine. Conversely, the precipitous collapse of spruce stands in the true boreal forests of northeastern. B C. is expected to be associated with reduced productivity as they are replaced by pine species. Boreal-Cordilleran and Moist Boreal Mixedwood forests in Alberta are less likely to undergo compositional change, while becoming somewhat more. productive We believe these model enhancements to be a significant improvement over existing formulations, but the resulting predictions must still be viewed with caution. Model limitations include: (1) the current inability of climate models to predict future variation in monthly temperature and precipitation; (2) sparse information on the phenological behavior of several important tree species; and (3) a poor understanding of the degree to which growth is constrained by different suboptimal climatic events.


Clark, William C.
"Scales of Climate Impacts"

Climates, ecosystems, and societies interact over a tremendous range of temporal and spatial scales. Scholarly work on climate impacts has tended to emphasize different questions, variables, and modes of explanation depending on the primary scale of interest. Much of the current debate on cause and effect, vulnerability, marginality, and the like stems from uncritical or unconscious efforts to transfer experience, conclusions, and insights across scales. This paper sketches a perspective from which the relative temporal and spatial dimensions of climatic, ecological, and social processes can be more clearly perceived, and their potential interactions more critically evaluated. Quantitative estimates of a variety of characteristic scales are derived and compared, leading to specific recommendations for the design of climate impact studies.


Cola, Lee De
"Fractal Analysis of a Classified Landsat Scene"

Remotely sensed images tend to be spatially very complicated, revealing regions of homogeneously classified pixels with quite convoluted perimeters. Fractal analysis, the study of complicated phenomena manifesting self-similarity at many scales, is suited to the description of the form and sizes of these. regions I apply fractal analysis to the patterns crated by eight land-cover classes from a Landsat TM image of northwest Vermont. The results suggest that forests manifest high fractal dimension and large regions, agricultural activities have large regions with fractal dimension inversely related to the intensity of cultivation, and urban land cover yields small regions with relatively high fractal dimension. Analysis of the individual urban regions provides a data structure in the form of a raster-based GIS which can be used to investigate the location and description of individual regions and to diagnose the reliability of the classification and labeling process.


Commoner, Barry
"Rapid Population Growth and Environmental Stress"

It is often suggested that rapid population growth, especially in developing countries, correspondingly intensifies environmental degradation, which must therefore be mitigated by reducing the rate of population growth. The validity of this assumption can be tested by means of an algebraic identity that relates the amount of a pollutant introduced into the environment to the product of three factors: population, affluence (the amount of goods produced per capita) and technology (the ratio of pollution generated to goods produced). For several forms of pollution that have a known origin in a specific production process (electricity production, use of motor vehicles, and consumption of inorganic nitrogen fertilizer), it is possible to compare the inferred rate of increase in pollution levels with the rate of population growth in developing countries. The results show that the rate of increase in pollution is largely determined by the technology factor, which governs the amount of pollution generated per unit of goods produced or consumed. This observation extends earlier evidence the both the increasing levels of pollution observed in developing countries and the results of efforts to reduce them support the view that the decisive factor determining environmental quality is the nature of the technology of production, rather than the size of population.


Cook, Edward R. and Julie Cole
"On Predicting the Response of Forests in Eastern North America to Future Climate Change"

Our ability to accurately predict the response of forests in eastern North America to future climatic change is limited by our knowledge of how different tree species respond to climate. When the climatic response of eastern hemlock is modeled across its range, we find that the assumed climatic response used in simulation models is not sufficient to explain how this species is presently responding to climate. This is also the case for red spruce growing in the northern Appalachian Mountains. Consequently, simulations of future changes to forests that include eastern hemlock and red spruce may need to be improved. We suspect that similar findings will be made when other tree species are studied in detail using tree-ring analysis. If so, our present understanding of how individual tree species respond to climate may not be adequate for accurately predicting future changes to these forests. Tree-ring analysis can increase our understanding of how climate affects tree growth in eastern North America and, hence, provide the knowledge necessary to produce more accurate predictions.


Crosson, Pierre R. and Norman J. Rosenberg
"Overview of the MINK Project"

Highlights of the previous papers in this series are reviewed. Methodology developed for the MINK study has improved the ability of impacts analysis to deal with questions of (1) spatial and temporal variability in climate change; (2) CO2-enrichment effects; (3) the reactions of complex enterprises (farms and forests) to climate change and their ability to adjust and adapt; and (4) integrated effects on current and, more particularly, on future regional. economies The methodology also provides for systematic study of adjustment and adaptation opportunities and of the inter-industry linkages that determine what the overall impacts on the regional economy might be. The analysis shows that with a 1930s "dust bowl" climate the region-wide economic impacts would be small, after adjustments in affected sectors. In this final paper we consider whether synergistic effects among sectoral impacts and more severe climate scenarios might alter this conclusion. The MINK analysis, as is, leads to the conclusion that a strong research capacity will be required to ensure that technologies facilitating adaptation to climate change will be available when needed. The capacity to deal with climate change also requires an open economy allowing for free trade and movement of people and for institutions that protect unpriced environmental values. More severe climate scenarios and negative synergisms can only strengthen these conclusions.


Cubasch, U., J. Waszkewitz, G. Hegerl, and J. Perlwitz
"Regional Climate Changes as Simulated in Time-Slice Experiments"

Three 30 year long simulations have been performed with a T42 atmosphere model, in which the sea surface temperature (SST) and sea-ice distribution have been taken from a transient climate change experiment with a T21 global coupled ocean-atmosphere model. In this so-called time-slice experiment, the SST values (and the greenhouse gas concentration) were taken at present time CO2 level, at the time of CO2 doubling and tripling.


Cushman, Robert M., Michael P. Farrell, and Frederick A. Koomanoff
"Climate and Regional Resource Analysis: The Effect of Scale on Resource Homogeneity"

General Circulation Models (GCMs) are currently used to project future. climate The output of the models is then used to evaluate the effect of a climatic change on resources such as agriculture, forestry, and water resources. The GCMs used in long-term climate studies vary widely in the geographic resolution of their predictions. The approximate matching of resource data to the geographic scale of GCMs is an important step in the evaluation of the effects of climatic change on resources. As gridcell size increases, however, the distribution of resources within cells becomes more heterogeneous, and it becomes more difficult to evaluate the regional effects of climatic change. We quantify the change in resource heterogeneity as a function of gridcell size. Four resource variables (wheat yield, percent forest cover, population density, and percent of land irrigated) are analyzed on the basis of county-averaged data, while assignment to major basins is based on exact watershed boundaries. A major change in resource heterogeneity within gridcells occurs at a grid length of from 1 2 degrees to 3 degrees.


Dale, Virginia H. and H. Michael Rauscher
"Assessing Impacts of Climate Change on Forests: The State of Biological Modeling"

Models that address the impacts of climate change on forests are reviewed at four levels of biological organization: global, regional or landscape, community, and tree. The models are compared for their ability to assess changes in fluxes of biogenic greenhouse gases, land use, patterns of forest type or species composition, forest resource productivity, forest health, biodiversity and wildlife habitat. No one model can address all of these impacts, but landscape transition models and regional vegetation and land-use models have been used to consider more impacts than the other models. The development of landscape vegetation dynamic models of functional groups is suggested as a means to integrate the theory of both landscape ecology and individual tree responses to climate change. Risk assessment methodologies can be adapted to deal with the impacts of climate change at various spatial and temporal scales. Four areas of research needing additional effort are identified: (1) linking socioeconomic and ecologic models; (2) interfacing forest models at different scales; (3) obtaining data on susceptibility of trees and forest to changes in climate and disturbance regimes; and (4) relating information from different scales.


Darmstadter, Joel
"Climate Change Impacts on the Energy Sector and Possible Adjustments in the MINK Region"

The discussion reviews the prevailing pattern of energy demand and supply in the MINK states, speculates on the region's long-term energy future in the absence and presence of greenhouse warming, and, in the latter case, considers energy sector adaptation to such a prospect. Climate-sensitive energy demand is dominated by heating and cooling in various sectors of the regional economy (around 20% of regional energy consumption) and by such agricultural applications as irrigation pumping and crop drying (around 5%). A climate-sensitive energy supply issue of some importance is the region's partial dependence on hydroelectric capacity in the upper Missouri river basin. The analysis finds that, unlike the rather significant impacts likely to be experienced by other sectors of the regional economy, the hypothesized warming trend will translate into only small net increases in energy demand; and that technological possibilities and policy measures are available to mute any serious climate effects on the energy sector.


Duinker, Peter N.
"Climate Change and Forest Management, Policy and Land Use"

Forests and woodland cover roughly one-third of the land surface of the world, and therefore deserve serious consideration in assessments of the socioeconomic implications of climate change. This article explores expected sensitivities of the world's managed forests, forest environment and forest sector to future climate change. A variety of studies are summarized. If significant climate changes occur over the next 50-75 years, forests throughout the world will undergo massive adjustments, many of which will in the short term be undesirable. Forest management has high potential for mitigating these effects, but only with support of insightful policy initiatives that take account of potential climatic changes.


Duxbury, John M.
"The Significance of Agricultural Sources of Greenhouse Gases"

The impact of development of land for agriculture and agricultural production practices on emissions of greenhouse gases is reviewed and evaluated within the context of anthropogenic radiative forcing of climate. Combined, these activities are estimated to contribute about 25%, 65%, and 90% of total anthropogenic emissions of carbon dioxide, methane, and nitrous oxide, respectively. Agriculture is also a significant contributor to global emissions of ammonia, carbon monoxide, and nitric oxide. Over the last 150 years, cumulative emissions of carbon dioxide associated with land clearing for agriculture are comparable to those from combustion of fossil fuel, but the latter is the major source of carbon dioxide at present and is projected to become more dominant in the future. Ruminant animals, rice paddies, and biomass burning are principal agricultural sources of methane, and oxidation of methane by aerobic soils has been reduced by perturbations to natural nitrogen cycles. Agricultural sources of nitrous oxide have probably been substantially underestimated due to incomplete analysis of increased nitrogen flows in the environment, especially via ammonia volatilization from animal manure, leaching of nitric oxide, and increased use of biological nitrogen fixation.


Easterling, W.E. and R.W. Kates
"Indexes of Leading Climate Indicators for Impact Assessment"

Could users of climate information for impact assessment be overlooking an important source of information in climate indicators? We argue that indexes of leading climate indicators of impacts may be usable knowledge for consumers and may provide guidance to the global climate observing community concerning the types of data and information that users need. Five classes of indexes are suggested: Climate Extremes Index (CEI) and Greenhouse Climate Response Index (GCRI) --such are already available from scientists at the U.S. National Climatic Data Center - plus proposed indexes of Hazard Warning, Ecosystem Health , and Energy Demand and Renewable Natural Resources. We conclude that the CEI and GCRI possess several necessary attributes to become usable knowledge; the other indexes have the potential to become usable knowledge, but remain to be implemented with climate data and fully evaluated.


Easterling, William E., III, Pierre R. Crosson, Norman J. Rosenberg, Mary S. McKenney, Laura A. Katz, and Kathleen M. Lemon
"Agricultural Impacts of and Responses to Climate Change in the Missouri-Iowa-Nebraska-Kansas (MINK) Region"

The climate of the 1930s was used as an analog of the climate that might occur in Missouri, Iowa, Nebraska, and Kansas (the MINK region) as a consequence of global warming. The analog climate was imposed on the agriculture of the region under technological and economic conditions prevailing in 1984/87 and again under a scenario of conditions that might prevail in 2030. The EPIC model of Williams et al. (1984), modified to allow consideration of the yield enhancing effects of CO2 enrichment, was used to evaluate the impacts of the analog climate on the productivity and water use of some 50 representative farm enterprises. Before farm level adjustments and adaptations to the changed climate, and absent CO2 enrichment (from 350 to 450 ppm), production of corn, sorghum and soybeans was depressed by the analog climate in about the same percent under both current and 2030 conditions. Production of dryland wheat was unaffected. Irrigated wheat production actually increased. Farm level adjustments using low-cost currently available technologies, combined with CO2 enrichment, eliminated about 80% of the negative impact of the analog climate on 1984/87 baseline crop production. The same farm level adjustments, plus new technologies developed in response to the analog climate, when combined with CO2 enrichment, converted the negative impact on 2030 crop production to a small increase. The analog climate would have little direct effect on animal production in MINK. The effect, if any, would be by way of the impact on production of feedgrains and soybeans. Since this impact would be small after on-farm adjustments and CO2 enrichment, animal production in MINK would be little affected by the analog climate.


Flavin, Christopher
"Storm Warnings: Climate Change Hits the Insurance Industry"

Staggered by an unprecedented series of hurricanes, floods, and fires, insurers are weighing the possibility that these catastrophes are the first real effects of human-induced climate change--and that the worst is yet to come. Their response could pit them squarely against the giant fossil fuel industry in the battle over reducing carbon emissions.


Frederick, Kenneth D.
"Climate Change Impacts on Water Resources and Possible Responses in the MINK Region"

The capacity to supply both instream and offstream water used under alternative climate conditions and likely future changes in population, technology, and water-using practices are examined through an adaptation of the framework developed in the Second National Water Assessment. Two measures of the adequacy of water supplies -- the availability of renewable supplies to provide for withdrawal and instream uses and the relation between desired instream flows and current streamflows--are used to examine the impact of the 1931-1940 analog climate (with and without CO2 enrichment) on Missouri, Iowa, Nebraska, and Kansas. (MINK) The impacts of the analog climate on water supplies are estimated from actual streamflow data and estimates of the differences in reservoir evaporation under the 1931-1940 analog and the 1951-1980 control climates. A modification of the Erosion Productivity Inventory Calculator (EPIC) model is used to estimate the impacts of the analog climate (with and without CO2 enrichment) on irrigation water use.


Frederick, Kenneth D., Indur M. Goklany , and Norman J. Rosenberg
"Conclusions, Remaining Issues, and Next Steps"

The workshop focused on methodologies to assess the impacts of climate change on terrestrial and aquatic ecosystem and their socioeconomic consequences. It did not deal in any detail with the other components (i.e., models designed to estimate changes in atmospheric concentrations of greenhouse gases or in climatic factors) of an integrated assessment shown in Figure 2 of the introduction. This final chapter discusses some of the issues addressed during the San Diego workshop and highlights a few of the major findings of the papers. Issues discussed below include limitations of past modeling efforts and impediments to developing better models of the impacts of climatic change on forest, grassland, and water resources; suggestions for future research both to develop better data and models and to employ existing data and modeling capabilities to improve the usefulness of climatic impact assessments for policy purposes; and the need for developing a common assessment framework.


Gates, Phil
"Climate Change: Implications for Conservation Management"

Global warming represents the most all-pervading influence for change in species distribution and the composition of plant and animal communities in the UK since the last Ice Age. How can conservationists respond to its challenges?


Goulden, Michael L., J. William Munger, Song-Miao Fan, Bruce C. Daube, and Steven C. Wofsy
"Exchange of Carbon Dioxide by a Deciduous Forest: Response to Interannual Climate Variability"

The annual net uptake of CO2 by a deciduous forest in New England varied from. 1 4 to 2.8 metric tons of carbon per hectare between 1991 and 1995. Carbon sequestration was higher than average in 1991 because of increased photosynthesis and in 1995 because of decreased respiration. Interannual shifts in photosynthesis were associated with timing of leaf expansion and senescence. Shifts in annual respiration were associated with anomalies in soil temperature, deep snow in winter, and drought in summer. If this ecosystem is typical of northern biomes, interannual climate variations on seasonal time scales may modify annual CO2 exchange in the Northern Hemisphere by 1 gigaton of carbon or more each year.


Grennfelt, P.
"Second Generation Abatement Strategies for NOx, NH3, SO2 and VOCs"

The UN ECE Convention on Long-Range Transboundary Air Pollution (LRTAP) has decided on reduction of transboundary air pollution in three protocols; one on sulphur, nitrogen oxides and volatile organic compounds (VOCs) respectively. These protocols are not sufficient to solve the air-pollution problem in Europe. Further reductions and agreements are necessary to achieve sustainable ecosystems. In further negotiations, which should be based on critical loads, it is important to consider that the regional air-pollution problem consists of a complicated matrix of compounds and effects. Thus, control of one problem will influence other problems, and control of one compound will affect the transport and effects of others. This is certainly the case for nitrogen oxides (NOx), which play an important role in acidification and eutrophication effects as well as in the formation of photochemical oxidants. This article discusses the scientific rationale for considering effects and their precursors together. Variations in effects and their causes are discussed and suggestions for a different approach to the future control of regional air pollution are given.


Grissino-Mayer, Henri D. and David R. Butler
"Effects of Climate on Growth of Shortleaf Pine (Pinus echinata Mill.) in Northern Georgia: A Dendroclimatic Study"

Recent applications of dendroecological techniques in the southeastern United States have focused upon the analysis of forest health to assess the rate, timing, and magnitude of changes in recent (<30 years) growth rates of southern pine species. However, knowledge of the pine growth/climate relationship is necessary before such assessments can be made. We developed a tree-ring index chronology from shortleaf pine growing in north-central Georgia and investigated the pine/growth relationship using correlation and response function analyses and multiple regression techniques. We found that shortleaf pine have a significant positive response to above-normal temperature during the current growing season, especially from May to July. We also found a strong time-dependent response by shortleaf pine to climate during the period studied (1910-1986). A regression model using certain monthly climatic variables as predictors explained 46% of the variablity in the index chronology. However, climate variables do not adequately model growth beginning in 1963 as the residuals from the climate/growth model show increased variability over the previous periods. This change in pine growth rates since 1963 must therefore be due to nonclimatic factors.


Hansen, James, Andrew Lacis, Reto Ruedy, Makiko Sato, and Helene Wilson
"How Sensitive is the World's Climate?"

We estimate climate sensitivity from observed climate change on time scales ranging fro the 100,000-year periods of major ice ages to brief periods of cooling after major volcanic eruptions. The real-world data indicate that climate is very sensitive, equivalent to a warming of 3+1°C for doubled atmospheric CO2. Observed global warming of 0.5°C in the past 140 years is consistent with anthropogenic greenhouse gases being the dominant climate-forcing in that period. But interpretation of current climate change is extraordinarily complex, because of lack of observations of several climate forcings as well as an unpredictable chaotic aspect of climate change. Climate change during the next decade may help confirm knowledge of climatic sensitivity, if global climate forcings are accurately observed.


Hauglustaine, D. A. and J.-C. Gérard
"Present and Future CFC and Other Trace Gas Warming: Results from a Seasonal Climate Model"

A seasonal one-and-a-half dimensional energy-balance climate model has been developed and is used to investigate and compare equilibrium and transient warming due to the accumulation of atmospheric trace gases. In particular, the relative importance of temperature increase due to chlorofluorocarbons (CFCs) during the next century is investigated on the basis of estimated future. emissions This model has a latitudinal resolution, and atmosphere-surface-deep ocean, land-sea partitioning, sea ice cover and ice depth calculated from a thermodynamic sea ice code, snow cover continuously varying in terms of temperature dependent parameterization and an interactive energy exchange between the oceanic mixed layer and the deep ocean. It is built to treat as many climate feedbacks as possible while remaining computationally fast enough to study problems involving the transient climatic response to external forcing changes over several centuries. The capability of the model to simulate the present climate is illustrated. Its sensitivity and seasonal response to perturbations have been investigated with an hypothetical step function doubling of atmospheric carbon dioxide and are in agreement with other model results, with a calculated equilibrium surface temperature increase of 3.4°C. The response of the climatic system to greenhouse trace gases increase (CO2, CH4, N2O and the 8 major CFCs) since 1850 and projected to year 2050 has been simulated. The equilibrium and transient responses are compared and the importance of considering both aspects for future climate predictions is stressed. Total surface temperature increases are 1.57°C and 3.70°C respectively for transient and equilibrium warming in 2050. Particular attention is focused on the relative contributions of each gas, showing that CO2 makes and will continue to make a major contribution, of more than 60%, to the total warming. The contribution of CFCs may reach more than 10% in 2050, with minor CFCs contributing to an important part of this contribution. The various CFC scenarios proposed by the recent UNEP-WMO report have been adopted for the period 1990-2050 in order to determine the impact of reduced future CFC emissions on the climatic response. The reduction of the CFC emissions may decrease the total warming by more than 6% in 2050. The latitudinal distribution of the transient temperature change shows an important interhemispheric asymmetry with continental regions much warmer than oceanic. areas


Hingane, L.S.
"Is a Signature of Socio-Economic Impact Written on the Climate?"

Surging population associated with large-scale colonization, tropical deforestation, and industrialization in parts of Asia that constitute over 60% of global population may lead to changes in the climate of that region. Identifying such changes is of great importance to scientists and policy makers. Concerning this, an approach is made here to assess the chemical composition in the troposphere over the region that happens to be the globe's longest belt of largest population density (LBLPD) and to assess the long term rainfall pattern of a tropical region lying along the belt of mountain ranges where an intense deforestation has been taking place on a large scale for several decades. Further, this paper reports the long term temperature and rainfall pattern of highly industrialized cities that have one of the fastest population growth. rates The tropospheric levels of CH4, CO and O3 over LBLPD are found to be remarkably higher than those over the stations lying outside the belt. The long term rainfall data on the belt of high mountain ranges shows a significant decreasing trend, whereas the data for adjacent coastal belt, which is normally the upwind side of the mountain belt, does not show any kind of trend. Surface air temperature and rainfall data for industrial cities with population greater than ten million shows a definite increasing trend whereas no trend is seen in data for adjacent non-industrialized towns.


Hubbard, K.G. and F.J. Flores-Mendoza
"Relating United States Crop Land Use to Natural Resources and Climate Change"

Crop production depends not only on the yield but also on the area harvested The yield response to climate change has been widely examined, but the sensitivity of crop land use to hypothetical climate change has not been examined directly Crop land-use regression models for estimating crop area indices (CAIs) - the percent of land used for corn, soybean, wheat, and sorghum production - are presented Inputs to the models include available water-holding capacity of the soil, percent of land available for rain-fed agricultural production, annual precipitation, and annual temperature. The total variance of CAI explained by the models ranged from 78% for wheat to 87% for sorghum, and the root-mean-square errors ranged from 1.74% for sorghum to 4.24% for corn. The introduction of additional climate variables to the models did not significantly improve their performance.


Jones, Elizabeth A., David D. Reed, and Paul V. Desanker
"Ecological Implications of Projected Climate Change Scenarios in Forest Ecosystems of Central North America"

Climate change scenarios in central North America were projected for selected weather stations using a stochastic daily weather simulation model. The projections were conditioned on changes in seasonal temperature and precipitation as predicted by several global climate models. The impacts of these projected changes on temperate forest ecosystems were evaluated through projected changes in such variables as average annual temperature, average growing season temperature, and the ratio of potential evaporation to precipitation during July and August. Even the mildest climate change scenario examined indicated that ecologically significant changes could occur in the composition and productivity of these forests. The possibility also exists that climatically induced regional decline episodes for a number of important commercial species could occur in the northern temperate forests of central North America.


Jongman, Rob H.G. and Martin A. Souer
"Landscape Ecological and Spatial Impacts of Climatic Change in Two Areas in the Netherlands"

The possible impact of climatic change on the water balance is analysed for the River Dommel and the Veluwe, an area drained by many very small brooks. A water balance is calculated for the winter and the summer period. With the help of four scenarios, based on GCMs, climate data from the dry year 1976 and land use scenarios the impact of climatic change and a possible superposed effect of acid precipitation is analysed. The results show that although the yearly changes in the water balance are small in some cases, in all cases the fluctuations in the water balance between winter and summer period increase. Changes in precipitation and evapotranspiration are multiplied in water storage and runoff. This will have consequences for water use planning and management.


Karl, Thomas R., Richard R. Heim, Jr, and Robert G. Quayle
"The Greenhouse Effect in Central North America: If Not Now, When?"

Climate models with enhanced greenhouse gas concentrations have projected temperature increases of 2° to 4°C, winter precipitation increases of up to 15 percent, and summer precipitation decreases of 5 to 10 percent in the central United States by the year 2030. An analysis of the climate record over the past 95 years for this region was undertaken in order to evaluate these projections. Results indicate that temperature has increased and precipitation decreased both during winter and summer, and that the ratio of winter-to-summer precipitation has decreased. The signs of some trends are consistent with the projections whereas others are not, but none of the changes is statistically significant except for maximum and minimum temperatures, which were not among the parameters predicted by the models. Statistical models indicate that the greenhouse winter and summer precipitation signal could have been masked by natural climatic variability, whereas the increase in the ratio of winter-to-summer precipitation and the higher rates of temperature change probably should have already been. detected If the models are correct it will likely take at least another 40 years before statistically significant precipitation changes are detected and another decade or two to detect the projected changes of temperature.


Karl, Thomas R.
"Missing Pieces of the Puzzle"

We continue to add trace greenhouse gases to the atmosphere at an unprecedented rate. Many scientists have suggested that the buildup of greenhouse gases will lead to an environmental catastrophe, while others argue that the climate system is either not very sensitive to this change or that the manner in which the climate is likely to change is more cogently described as the "Garden of Eden". Six well-known scientists on this topic provide a basis for an examination of the evidence in support of these positions. The primary difficulty relates to uncertainties about the sensitivity of the climate system. Imprecise measurements of past rates of observed climate change, and inadequate data regarding the timing and magnitude of many climatic forcings preclude precise. answers As a result, it is impossible to completely dismiss extreme positions.


Kauppi, Pekka E., Kari Mielikainen, and Kullervo Kuusela
"Biomass and Carbon Budget of European Forests, 1971 to 1990"

In severely polluted areas, such as locally in Montshegorsk in northwestern Russia, all trees have died. However, measurements from Austria, Finland, France, Germany, Sweden, and Switzerland show a general increase of forest resources. The fertilization effects of pollutants override the adverse effects at least for the time being. Biomass was built up in the 1970s and 1980s in European forests. If there has been similar development in other continents, biomass accumulation in nontropical forests can account for a large proportion of the estimated mismatch between sinks and sources of atmospheric carbon dioxide.


Kernyi, Attila and Peter Csorba
"Assessment of the Sensitivity of the Landscape in a Sample Area in Hungary for Climatic Variability"

In the northeastern part of Hungary near the township of Tokaj a landscape research project has been performed in a 9 km2 area. The aim of this study is to examine the possibilities of expressing the climatic sensitivity of the given small landscape unit by analysing the capabilities of such a small sample area and synthesizing the data obtained. The landscape analysis consisted of field and laboratory measurements, theoretical calculations, analyses of maps, as well as the construction of thematic maps (on the scale of 1:10,000) and cartograms.


Kerr, Richard A.
"A New Dawn for Sun-Climate Links?"

The long-dismissed idea that the sun could be a major driver of climate change is gaining new adherents as researchers detect the pulse of the sun in the ocean, on land, and in glacial ice.


Kim, Kwang-Y and Gerald R. North
"Regional Simulations of Greenhouse Warming Including Natural Variability"

The perception of the hypothesized greenhouse effect will differ dramatically depending upon the location on the earth at which the effect is analyzed. This is due mainly to two causes: (1) the warming signal depends upon the position on the earth, and (2) the natural variability of the warming has a strong position. dependence To demonstrate these phenomena, simulations were conducted of the surface temperature field with a simple stochastic climate model that has enough geographical resolution to see the geographic dependence. The model was tuned to reproduce the geographical distribution of the present climate, including its natural variability in both the variance and the space-time correlation structure. While such effects have been discussed elsewhere with even more realistic climate models, it is instructive to actually see simulations of time series laid side by side in order to easily compare their differences and similarities. Because of the model's simplicity, the causes of the variations are easy to analyze Not surprisingly, some realizations of the temperature for some local areas show countertrends for a period of several decades in the presence of the greenhouse warming.


Kumar, Arun, Ants Leetmaa, and Ming Ji
"Simulations of Atmospheric Variability Induced by Sea Surface Temperatures and Implications for Global Warming"

An atmospheric general circulation model was forced with observed interannual changes in the global sea surface temperatures (SSTs) for the period 1982 to 1993. The simulated seasonal surface air temperature patterns over land areas closely resemble the observed. Over most of the globe, the patterns also resemble those associated with El Nino events and are also reproduced in simulations with weak warm tropical SSTs near the date line. An exception is northern Asia, where the mechanisms for the observed warming are unclear. The results suggest that enhanced air-sea interactions resulting from recent, more persistent warm oceanic conditions in the tropics contributed to the observed global warming trend during this period.


Lee, Christopher T. and Stuart E. Marsh
"The Use of Archival Landsat MSS and Ancillary Data in a GIS Environment to Map Historical Change in an Urban Riparian Habitat"

Recent changes in the condition of the riparian habitat of the Tanque Verde Creek in Tucson, Arizona prompted an investigation of the dynamics of the native plant communities, hydrology, and the climate in the area. The project was an initial attempt to assess and monitor the changing condition of native vegetation along the Tanque Verde Creek during the period 1983 through 1989, and discover if mapped changes in vegetation patterns could be correlated with available ground data.


Lein, James K.
"The Assessment of Land Use/Land Cover Impacts On Local Climate"

The impact of land use change on the pattern of urban micro-climate is evaluated through the applications of a computer simulation model that couples digital energy balance calculations with a Markov based procedure for projecting land use change. The model is applied to a portion of western Cuyahoga County, Ohio, and an index of micro-climate is derived by the method of R-mode factor analysis in order to trace variations in local climate as the dynamics of the land use system are simulated for the period 1969 to 1999. The conversion of land from agricultural use to residential formed the principal expression of change in the system, and contributed to a projected 0-16 degree C increase in mean annual temperature for the study site.


Lindzen, Richard
"Absence of Scientific Basis"

Current concerns over significant global warming are based on simple, plausible physical arguments that increasing CO2 levels will lead to some warming. Model predictions of large warming depend on projected large increases in atmospheric CO2, and mechanisms within the models which act to greatly amplify the climate response to increasing CO2. The projections depend on questionable economic, population, and energy scenarios; they also depend on clearly inadequate chemical models which serve to exaggerate the fraction of emitted CO2 remaining in the atmosphere. The amplification mechanisms (positive feedbacks) depend on what is likely to be a severe misrepresentation of the relevant physical processes: moisturization of the atmosphere and cloud formation. Recent data suggest that these processes may be acting in a manner opposite to what current models produce. Under the circumstances, the possibility of large warming, while not disproven, is also without a meaningful scientific basis.


Manne, Alan S. and Leo Schrattenholzer
"Global Scenarios for Carbon Dioxide Emissions"

The status of global greenhouse-gas emissions is summarized as of December. 1992 (Report describes the status of greenhouse-gas emissions as reported by Challenge, a network of researchers exploring efficient measures to reduce the risk of adverse climate change).


Martin, E. B. and E. M. Scott
"The Detection of Change in Spatial Processes"

The question of whether the spatial distribution of a characteristic of interest has changed over time is of interest within the environmental sciences, since spatial evolution may be informative about the underlying environmental processes affecting the characteristic. Techniques currently available for investigating change in spatially defined processes are in the main either subjective in nature or else ignore the spatial component. A hypothesis testing procedure based on a contour representation of the spatial distribution of the characteristic of interest has been developed and will be described in this paper. The approach does not require that observations be recorded at the same location, and thus is generally applicable. The degree of change between the contoured surfaces has been quantified in terms of various statistics which describe the rotational, translational and scalar aspects of change. The properties (sic) of the various statistics have been investigated through an extensive simulation study, which examined a range of factors, including the surface fitting procedure (Kernal density estimation), the number and choice of contour levels, and the effect of random noise present within the system due to the measurement process. Finally the method is illustrated on the historical climate record of the U.S.A. The temperature field of the contiguous U.S.A. is studied for change over a 50 year period.


Maskell, Kathy
"Basic Science of Climate Change"

Much attention has lately been focused on "global warming"-the increase in temperature which may result from man's emission of carbon dioxide and other greenhouse gases into the atmosphere. Research into climate change has been in progress for many years but it came to the forefront of the public's attention partly because of the warm global mean temperatures in the 1980s and early 1990s.


McBean, Gordon A.
"Global Change Models-A Physical Perspective"

The World Climate Research Programme has the dual objectives of determining the extent of climate predictability and the influence of human activities on. climate To meet these objectives, the WCRP has instituted a set of research programs focusing on specific aspects of the physical climate system. Global climate models are at the core of the WCRP. Models provide a structural framework around which to organize research; they are used to identify knowledge gaps and to assimilate data; and they are used for prediction and simulation. Time scales of interest stretch from those of numerical weather prediction, through interannual variability to decadal climate change. As the time scale of interest expands we must include more and more components of the climate system. Physically-based global climate models will also be the framework upon which to build full global change models. Modelling and other research activities internationally coordinated by the WCRP have provided the basis for the Intergovernmental Panel on Climate Change (IPCC) assessment of global warming and the proposed international centre for climate prediction research. A major thrust of the EXRP is to reduce the uncertainties in simulations of climatic response to increasing concentrations of greenhouse gases. There is need for a continuous interaction between the modelling community and those scientists studying the processes and data. Through international coordination and national contributions considerable progress has been made over the past decade and we anticipate similar success in the future.


Mendelsohn, Robert and Norman J. Rosenberg
"Framework for Integrated Assessments of Global Warming Impacts"

This paper provides a framework for integrated assessment of the impacts of climate change on natural resources and sets the stage for papers that follow in this volume (special issue). Integrated assessments are used to organize large quantities of technical information bearing on complex issues (environmental and others) in ways that facilitate application of the information in decision making and policy setting. Any integrated assessment must be based on the best available. information For that reason this paper includes a 'primer' on the current (and presumably best available) understanding of the science underlying climatic. change The remainder of the paper describes the component parts of one possible framework for integrated assessment.


Michaels, Patrick J.
"Benign Greenhouse"

Several lines of evidence are emerging that suggest that the "popular vision" of global warming--major agricultural damage, disastrous sea-level rise, and ecological disequilibrium--is flawed. The popular vision is driven primarily by the prospect of enhanced daytime warming, particularly in summer. What has been observed is a warming that is beneath the projections that support the popular vision, and a warming that has occurred virtually all during the night in the Northern Hemisphere. In the Southern Hemisphere there is also evidence of disproportionate night warming. Several sources of data indicate that this night warming has been caused by an increase in cloudiness that could be a consequence of the greenhouse enhancement itself. The results of the night warming--longer growing seasons, little change in moisture stress, and a possible increase in ice volume--are opposite to the popular vision of climatic change.


Miller, Roberta Balstad
"Interactions and Collaboration in Global Change Across the Social and Natural Sciences"

In its second decade, the study of global change will require increased research on the interactions of physical, biological and anthropogenic processes. The absence of prior substantive collaboration across the natural and social sciences has resulted in the delineation of a well-articulated global change research agenda that calls for, but does not yet encompass, significant interdisciplinary collaboration. There are few models of the kind of successful collaboration that is needed, and little concrete evidence of how it should be. attempted This paper makes a distinction between cooperative, but partitioned multidisciplinary research, and collaborative interdisciplinary research. The latter will only be possible if scientists from collaborating fields begin to alter the way they think about global data, and prepare to take the time needed to address the problems.


Millette, Thomas L., Amulya R. Tuladhar, Roger E. Kasperson, and B.L. Turner, II
"The Use and Limits of Remote Sensing for Analysing Environmental and Social Change in the Himalayan Middle Mountains of Nepal"

The 'middle mountains' zone of the Himalayas is a region in stress due to human actions undertaken in a high energy environment. This study is an initial exploration of this region of human environment 'criticality' or 'endangerment' through the lens of remotely sensed imagery. Three villages in the Middle Mountains representing different environmental and socioeconomic situations were examined by means of image processing of Landsat Thematic Mapper data, coupled with ground studies, in order to identify indicators of social and environmental change expressed in the landscape. Preliminary results are both encouraging and. cautioning Indications are that 30 metre resolution satellite data can provide useful information associated with broad land management practices, landesque capital, and land cover changes. Such data are important for the debate on Himalayan environmental degradation,, but ideally need to be combined with ground truthing, fieldwork, and interviewing to provide an assessment of types and causes of environmental change.


Mooney, Harold A. and George W. Koch
"The Impact of Rising CO2 Concentrations on the Terrestrial Biosphere"

Large advances have been made in linking terrestrial biospheric and atmospheric processes in real time. Further, it is now possible to model the potential response of the Earth's primary productivity to the changing climate and to changes in atmospheric CO2 concentration. We still have limited information, however, on the total responses of ecosystems to enhanced CO2 because of the complex web of possible interactions. What is needed are experiments on whole ecosystems under enhanced CO2 in which all of the potential interactions and feedbacks can be monitored, including plant-microbe, plant-herbivore, and plant-atmosphere interactions. A global network of experiments in the major biomes of the world is being developed within the International Geosphere-Biosphere Programme (IGBP) to resolve questions related to the implications of a changed pattern of biomass distribution in the biosphere.


Nakicenovic, Nebojsa, Arnulf Grubler, Atsushi Inaba, Sabine Messner, Sten Nilsson, Yoichi Nishimura, Hans-Holger Rogner, Andreas Schafer, Leo Schrattenholzer, Manfred Stubegger, Joel Swisher, David Victor , and Deborah Wilson
"Long-Term Strategies for Mitigating Global Warming"

This special issue reviews technological options for mitigating carbon dioxide (CO2) emissions. The options analyzed include efficiency improvements, renewable energies, clean fossil and zero-carbon energy technologies, carbon sequestration and disposal, enhancement of natural carbon sinks (halting deforestation, afforestation, and other sink enhancement options), and geo-engineering measures to compensate for increases in CO2 concentrations. Reduction potentials, costs, and the relative contribution of individual options, as well as their limiting factors and possible timing of introduction and diffusion, are discussed. The study concludes with a discussion of methodological issues and of trade-offs and constraints for implementation strategies to mitigate anthropogenic sources of change in the global carbon cycle.


Nellis, M. Duane and John M. Briggs
"The Effect of Spatial Scale on Konza Landscape Classification Using Textural Analysis"

Spatial scale is inherent in the definition of landscape heterogeneity and. diversity For example, a landscape may appear heterogeneous at one scale but quite homogeneous at another scale. In assessing the impact of burning and grazing on the Konza Prairie Research Natural Area (a tallgrass prairie), spatial scale is extremely important. Textural contrast algorithms were applied to various scales of remote sensing data and related to landscape units for assessment of heterogeneity under a variety of burning treatments. Acquired data sets included Landsat multispectral scanner (MSS), with 80 m resolution, Landsat thematic mapper (TM), with 30 m resolution, and high resolution density sliced aerial photography (with a 5 m resolution). Results suggest that heterogeneous areas of dense patchiness (e.g., unburned areas) must be analyzed at a fined scale than more homogeneous areas which are burned at least every four years.


O'Neill, R.V., J.R. Krummel, R.H. Garnder, G. Sugihara, B. Jackson, D.L. DeAngelis, B.T. Milne, M.G. Turner, B. Zygmunt, S.W. Christensen, V.H. Dale, and R.L. Graham.
"Indices of Landscape Pattern"

Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.


Oerlemans, Johannes
"Quantifying Global Warming from the Retreat of Glaciers"

Records of glacier fluctuations compiled by the World Glacier Monitoring Service can be used to derive an independent estimate of global warming during the last 100 years. Records of different glaciers are made comparable by a two-step scaling procedure: one allowing for differences in glacier geometry, the other for differences in climate sensitivity. The retreat of glaciers during the last 100 years appears to be coherent over the globe. On the basis of modeling of the climate sensitivity of glaciers, the observed glacier retreat can be explained by a linear warming trend of 0.66 kelvin per century.


Parikh, Jyoti K. and J.P. Painuly
"Population, Consumption Patterns and Climate Change: A Socioeconomic Perspective from the South"

Although 25% of the population in developed countries consume more than 75% of the natural resources the misconceptions persist that population is a major threat to the world's natural resources. This article puts unsustainable consumption patterns and population in proper perspective. Local environmental problems in developing countries, viz. safe drinking water, clean fuels, sanitation have been emphasized as priority problems compared to global environmental problems. It is also suggested that a tradable-emissions quota system for greenhouse gases constitutes an efficient and socially just mechanism for tackling local and global environmental problems. Greenhouse-gas emission activities and socioeconomic aspects of emissions reductions, from various activities, are discussed.


Parry, M.L., J.E. Hossell, P.J. Jones, T. Rehman, R.B. Tranter, J.S. Marsh, C. Rosenzweig, G. Fischer, I.G. Carson, and R.G.H. Bunce
"Integrating Global and Regional Analyses of the Effects of Climate Change: A Case Study of Land Use in England and Wales"

The purpose of this paper is to exemplify a means by which an integrated assessment can be made of global and regional effects on land use of climate. change This is achieved by use of data on the effects of climate change on world food prices as inputs to a regional land use allocation model. Data on world prices are drawn from a recent global study of climate change and crop yields. In a case study of England and Wales a land allocation model is used to infer changes of land use that are the product of the integrated effect of climate-induced global price changes and climate-related changes of yield in England and Wales. This combination of changed prices and yield potential is used to calculate the land use providing the highest returns for each of 155,235 1 km2 cells of land in England and Wales for a future assumed for the year 2060 (without climate change) and then for that same environment with climate change. The difference between these two is then treated as an estimated effect resulting from climate change.


Pastor, John and Michael Broschart
"The Spatial Pattern of a Northern conifer-Hardwood Landscape"

A geographic information system, fractal analyses, and statistical methods were used to examine the spatial distributions of old growth hemlock, northern hardwood, mixed hardwood/hemlock stands and wetlands with respect to each other and also soils and topography. Greater than 80% of the stands of any covertype were less than 20 ha in area. Nearly pure hemlock and northern hardwood stands were associated with soils having a fragipan, while mixed hardwood/hemlock stands were associated with sandier soils. Hemlock stands were distributed independently of hardwood and mixed hardwood/hemlock stands, but hardwood and mixed hardwood/hemlock stands were usually surrounded by hemlock. Bogs and lakes were usually surrounded by hemlock stands and are distributed independently of hardwood stands. The shapes of all stands vary from extremely simple to extremely complex, with a general tendency for hemlock stands to be more convoluted than. hardwoods The analyses suggest segregation across soil types and a disturbance regime favoring the establishment of hardwoods and mixed hardwood/hemlock stands in a hemlock matrix as reasons for the origin of the observed spatial patterns.


Pickett, S.T.A. and M.L. Cadenasso
"Landscape Ecology: Spatial Heterogeneity in Ecological Systems"

Many ecological phenomena are sensitive to spatial heterogeneity and fluxes within spatial mosaics. Landscape ecology, which concerns spatial dynamics (including fluxes of organisms, materials, and energy) and the ways in which fluxes are controlled within heterogeneous matrices, has provided new ways to explore aspects of spatial heterogeneity and to discover how spatial pattern controls ecological processes.


Pielke, R. A. and R. Avissar
"Influences of Landscape Structure on Local and Regional Climate"

This paper discusses the physical linkage between the surface and the atmosphere, and demonstrates how even slight changes in surface conditions can have a pronounced effect on weather and climate. Observational and modeling evidence are presented to demonstrate the influence of landscape type on the overlying atmospheric conditions. The albedo, and the fractional partitioning of atmospheric turbulent heat flux into sensible and latent fluxes is shown to be particularly important in directly affecting local and regional weather and. climate It is concluded that adequate assessment of global climate and climate change cannot be achieved unless mesoscale landscape characteristics and their changes over time can be accurately determined.


Plotnik, Roy E., Robert H. Gardner, and Robert V. O'Neill
"Lacunarity Indices as Measures of Landscape Texture"

Lacunarity analysis is a multi-scaled method of determining the texture associated with patterns of spatial dispersion (i.e., habitat types or species locations) for one-, two- or three-dimensional data. Lacunarity provides a parsimonious analysis of the overall fraction of a map or transect covered by the attribute of interest, the degree of contagion, the presence of self-similarity, the presence and scale of randomness, and the existence of hierarchical structure. For self-similar patterns, it can be used to determine the fractal dimension. The method is easily implemented on the computer and provides readily interpretable graphic results. Differences in pattern can be detected even among very sparsely occupied maps.


Prentice, I. Colin, Patrick J. Bartlein, and Thompson Webb, III
"Vegetation and Climate Change in Eastern North America Since the Last Glacial Maximum"

Response surfaces describing the empirical dependence of surface pollen percentages of 13 taxa on three standard climatic variables (mean July temperature, mean January temperature, and mean annual precipitation) in eastern North America were used to infer past climates from palynological data. Inferred climates at 3,000-year intervals from 18,000 years ago to the present, based on six taxa (spruce, birch, northern pines, oak, southern pines, and prairie forbs) were used to generate time series of simulated isopoll maps for these taxa and seven others (hickory, fir, beech, hemlock, elm, alder, and sedge). The simulations captured the essential features of the observed isopoll maps for both sets of taxa, including differences in migration patterns during the past 10,000 years that have previously been attributed to differential migration lag. These results establish that the continental-scale vegetation patterns have responded to continuous changes in climate from the last glacial maximum to the present, with lags less than or equal to 1500 years. The inferred climatic changes include seasonality changes consistent with orbitally controlled changes in insolation, and shifts in temperature and moisture gradients that are consistent with modelled climatic interactions of the insolation changes with the shrinking Laurentide ice sheet. These results post new ecological questions about the processes by which vegetated landscapes approach dynamic equilibrium with their changing environment.


Nemani, Ramakrishna R. and Steven W. Running
"Satellite Monitoring of Global Land Cover Changes and Their Impact on Climate"

Land cover is crucial, spatially and temporally varying component of global carbon and climate systems. Therefore accurate estimation and monitoring of land cover changes is important in global change research. Although, land cover has dramatically changed over the last few centuries, until now there has been no consistent way of quantifying the changes globally.


Reilly, John M. and Kenneth R. Richards
"Climate Change Damage and the Trace Gas Index Issue"

Efficient policies to control trace gas emissions require estimation of an appropriate "exchange rate" among these gases; i.e., the relative value of reducing emissions of each gas. A dynamic stock pollutant model is developed that considers damages associated with both non-climatic and climatic effects of the gases, differing atmospheric lifetimes of the gases, the discount rate, and non-linear damages. The index value and the shadow value of control are estimated for carbon dioxide, carbon monoxide, methane, nitrous oxide and the 4 major chlorofluorocarbons (CFCs). The value of control for short-lived relative to long-lives gases is lower for low discount rates and quadratic compared with linear damages. The relative value of control for all gases falls relative to carbon dioxide if one considers the direct beneficial effects of carbon dioxide on agriculture. The general approach developed in the paper may have application for other environmental problems where multiple substances pose individual risks but also jointly contribute to a single risk.


Riebsame, William E.
"Adjusting Water Resources Management to Climate Change"

The nature of climate impacts and adjustment in water supply and flood management is discussed, and a case study of water manager response to climate fluctuation in California's Sacramento Basin is presented. The case illuminates the effect on climate impact and response of traditional management approaches, the dynamic qualities of maturing water systems, socially imposed constraints, and climate extremes. A dual pattern of crisis-response and gradual adjustment emerges, and specific mechanisms for effecting adjustment of water management systems are identified. The case study, and broader trends in the U.S. water development, suggest that oversized structural capacity, the traditional adjustment to climate variability in water resources, may prove less feasible in the future as projects become smaller and new facilities are delayed by economic and environmental concerns.


Riebsame, William E.
"Climate Hazards, Climatic Change and Development Planning"

The threat of global warming calls for a new approach to development planning, one that incorporates (a) analysis of the sensitivity of resource systems to variations in climate and environmental change; (b) gradual adjustment to climate change; and (c) expansion of the repertoire of options, to avoid being pressured into premature action or paralysed by uncertainty. The author asserts that such a repertoire should include actions that are easily and cheaply implemented and reversed, and that adjustments should expand rather than limit future options. Planners should expand on a 'tie-in' strategy that links the uncertain threat of climatic change to the certainty that current resource management systems contribute to current environmental problems. The mitigation of current natural hazards should be linked to concerns about climatic warming so that actions taken today have both immediate and long-term benefits.


Riebsame, William E., William B. Meyer, and B.L. Turner, II
"Modeling Land Use and Cover as Part of Global Environmental Change"

Land use and cover changes are important elements of the larger problem of global environmental change. Land use patterns result in land cover changes that cumulatively affect the global biosphere and climate. We describe efforts to analyze the driving forces behind land transformations and to create land use models that can be linked to other types of global change models. Two efforts to model land use in the U.S. are reviewed. One projects aggregate agricultural, forest, and range land, and the other attempts to model forest land use change at the parcel scale in two mountain landscapes. We conclude with suggestions for new approaches that could clarify the role of land use/cover change in global change and in natural resources management.


Root, Terry L. and Stephen H. Schneider
"Ecology and Climate: Research Strategies and Implications"

Natural and anthropogenic global changes are associated with substantial ecological disturbances. Multiscale interconnections among disciplines studying the biotic and abiotic effects of such disturbances are needed. Three research paradigms traditionally have been used and are reviewed here: scale-up, scale-down, and scale-up with embedded scale-down components. None of these approaches by themselves can provide the most reliable ecological assessments. A fourth research paradigm, called strategic cyclical scaling (SCS), is relatively more effective. SCS involves continuous cycling between large- and small-scale studies, thereby offering improved understanding of the behavior of complex environmental systems and allowing more reliable forecast capabilities for analyzing the ecological consequences of global changes.


Rosenberg, Norman J., Pierre R. Crosson, Kenneth D. Frederick, William E. Easterling, III, Mary S. McKenney, Michael D. Bowes, Roger A. Sedjo, Joel Darmstadter, Laura A. Katz, and Kathleen M. Lemon
"The MINK Methodology: Background and Baseline"

A four step methodology has been developed for study of the regional impacts of climate change and the possible responses thereto. First, the region's climate sensitive sectors and total economy are described (Task A, current baseline). Next a scenario of climate change is imposed on the current baseline (Task B, current baseline with climate change). A new baseline describing the climate sensitive sectors and total regional economy is projected for some time in the future (Task C, future baseline, year 2030) in the absence of climate change. Finally, the climate change scenario is reimposed on the future baseline (Task D, future baseline with climate change). Impacts of the climate change scenario on the current and future regional economies are determined by means of simulation models and other appropriate techniques. These techniques are also used to assess the impacts of an elevated CO2 concentration (450 ppm) and of various forms of adjustments and adaptations.


Rosenzweig, Cynthia and Daniel Hillel
"Agriculture in a Greenhouse World"

While agriculture in some temperate climate regions may benefit from global climate change, tropical and subtropical regions may suffer. Even where potential production will improve, the required adjustments may disrupt ecosystems and land-use patterns. Agricultural zones will shift toward high latitudes, while heat stress and increased droughts will reduce productivity in lower latitudes. On the positive side, higher CO2 may enhance photosynthesis and water-use. efficiency Future hazards include sea-level rise, insect infestation, and greater evaporation losses. Some agricultural activities augment the greenhouse effect by releasing CO2, CH4, and N2O. Understanding the potential impacts of climate change is a prerequisite to developing societal responses.


Rosenzweig, Cynthia and Martin L. Parry
"Potential Impact of Climate Change on World Food Supply"

A global assessment of the potential impact of climate change on world food supply suggests that doubling of the atmospheric carbon dioxide concentration will lead to only a small decrease in global crop production. But developing countries are likely to bear the brunt of the problem, and simulations of the effect of adaptive measures by farmers imply that these will do little to reduce the disparity between developed and developing countries.


Rudel, Thomas K.
"Population, Development, and Tropical Deforestation: A Cross-national Study"

In the past 15 years, the international development community has focused on rapid tropical deforestation with considerable concern. This paper makes a preliminary effort to specify the causes of tropical deforestation. In the early 1980s a special United Nations' study generated reliable estimates of rain-forest destruction for 36 developing countries. A cross-sectional analysis which links variations in deforestation with variations in population growth and the availability of capital indicates the socioeconomic processes which sustain tropical deforestation. Two measures of population growth predict deforestation, and among countries with large rain forests, the availability of capital also predicts deforestation. Measures of peripheral country dependency on core nations fail to explain variations in deforestation. The implications of these findings for policies designed to slow rates of deforestation are briefly explored.


Running, Steven W., Thomas R. Loveland, and Lars L. Pierce
"A Vegetation Classification Logic Based on Remote Sensing for Use in Global Biogeochemical Models"

A simple new classification logic for global vegetation is proposed. The critical features of this classification are that: it is based on simple, observable, unambiguous characteristics of vegetation structure that are important to ecosystem biogeochemistry and can be measured in the field for validation; the structural characteristics can be determined by remote sensing, so that repeatable and efficient global re-classifications of existing vegetation will be possible; and the defined vegetation classes directly translate into the biophysical parameters of interest by global climate and biogeochemical models. A first test of this logic for the continental United States is presented based on an existing 1 km Normalized Difference Vegetation Index database. Currently recognized global biome classes can easily be derived from this classification by adding climate descriptors and defining mixtures of these fundamental six vegetation classes.


Ryszkowski, Lech and Andrzej Kedziora
"Modification of the Effects of Global Climate Change by Plant Cover Structure in an Agricultural Landscape"

To grasp the impact of plant cover structure on heat balance structure the components of heat balance of six ecosystems and two landscapes were calculated by using a mathematical model. The following three types of meteorological conditions during the growing season were taken into consideration: (1) real meteorological conditions for normal, wet and dry years chosen from observations made in the period 1956-1992; (2) assumed model meteorological conditions for a normal year, (averages from long-term vales of meteorological data), and for an extremely dry and hot year, and an extremely wet and cold year; (3) predicted meteorological conditions resulting from global changes. The analysis of various meteorological situations has shown that the plant cover has mitigating capacities in relation to the presumed effects of global climate change. Thus, in attempts to predict global changes at local level, the mitigating effects of plant cover must be taken into consideration.


Schlesinger, Michael E.
"Greenhouse Policy"

How quickly we must respond, and by how much, to the threat of global warming depends on how much increasing greenhouse-gas concentrations will change climate, and what the consequences of such a climate change will be. Yet our knowledge of these climate changes is uncertain. I provide a basis for understanding why this is so with information about the greenhouse effect, climate modeling and simulation, and economic and policy analysis. I examine a sequential-decision strategy for abating climate change wherein either moderate emissions reduction-energy conservation alone-or aggressive emissions reduction-energy conservation plus switching to non-fossil fuels-is begun in the near-term (1992 to 2002). Results show that the difference in emission rates and costs between the moderate and aggressive near-term policies is much smaller than the difference in emission rates and costs between the different climate targets. Thus, if future research shows that the damage cost of climate change is high, the optimum climate target will be low and the global consumption of fossil fuels must be sharply reduced much earlier than if the damage cost of climate change is low, regardless of which near-term policy is chosen.


Schneider, Stephen H.
"Degrees of Certainty"

Debate in the media over global warming often mixes what is well known with what is speculative, thereby leading to an artificially confusing impression that scientists share no consensus of the probable magnitude, timing and potential seriousness of the environmental and societal consequences of the documented and well-understood buildup of various greenhouse-enhancing gases in the atmosphere. Indeed, widespread concern exists over the plausibility of temperature increases of 1 to 5°C in the 21st century, and that the mid to upper part of that range could imply dramatic restructuring of ecosystems or communities. I discuss the difficulty in interpreting the 0.5+0.2°C 20th century warming trend as "proof" of greenhouse-gas-induced global warming in light of possible climatic-change causal factors, such as industrial aerosols, natural fluctuations, or changes in solar. output How to act is controversial, and economic model results showing potential abatement costs of carbon taxes are discussed.


Schneider, Stephen H.
"Detecting Climatic Change Signals: Are There Any "Fingerprints"?"

Projected changes in the Earth's climate can be driven from a combined set of forcing factors consisting of regionally heterogeneous anthropogenic and natural aerosols and land use changes, as well as global-scale influences from solar variability and transient increases in human-produced greenhouse gases. Thus, validation of climate model projections that are driven only by increases in greenhouse gases can be inconsistent when one attempts the validation by looking for a regional or time-evolving "fingerprint" of such projected changes in real climate data. Until climate models are driven by time-evolving, combined, multiple, and heterogeneous forcing factors, the best global climatic change "fingerprint" will probably remain a many-decades average of hemispheric-to global-scale trends in surface air temperatures. Century-long global warming (or cooling) trends of 0.5°C appear to have occurred infrequently over the past several thousand years-perhaps only once or twice a millennium, as proxy records. suggest This implies an 80 to 90 percent heuristic likelihood that the 20th-century 0.5+0.2°C warming trend is not a wholly natural climatic fluctuation.


Schroeder, Paul and Lew Ladd
"Slowing the Increase of Atmospheric Carbon Dioxide: A Biological Approach"

Planting trees to act as carbon sinks has been suggested as a way to slow the increase of atmospheric CO2. Forestry growth and yield models were used to estimate that it would take 192 million hectares of Douglas-fir (Pseudotsuga menziesii) or 250 million hectares of Loblolly pine (Pinus taeda) to capture and store the United States' anthropogenic carbon emissions for an assumed period of 50 yr, at current emission rates. Although maximum growth rates are similar for both species, Douglas-fir requires less area because of its greater ability to store carbon, and its ability to maintain a high growth rate for a longer period of time. The usefulness of a particular species also depends in part on the length of the planning horizon and the forestry project. For periods of 50 or more years, it is important to consider a species' cumulative carbon storage potential rather than its potential maximum growth rate at some point during its life cycle. Forestation (reforestation and afforestation) appears to be feasible as a possible component of a comprehensive strategy for managing the CO2 problem, but it must be practiced globally to be effective.


Schroeder, Paul
"Agroforestry Systems: Integrated Land Use to Store and Conserve Carbon"

Agroforestry is a promising land use practice to maintain or increase agricultural productivity while preserving or improving fertility. From the perspective of climate change and the global carbon cycle, agroforestry practices are attractive for 2 reasons: they directly store carbon in tree components, and they potentially slow deforestation by reducing the need to clear forest land for. agriculture An extensive literature survey was conducted to evaluate the carbon dynamics of agroforestry practices and to assess their potential to store carbon. Data on tree growth and wood production were converted to estimates of carbon. storage Surveyed literature showed that median carbon storage by agroforestry practices was 9 t C ha-1 in semi-arid, 21 t C ha-1 in sub-humid, 50 t C ha-1 in humid, and 63 t C ha-1 in temperate ecoregions. (NOTE: the -1 are all superscript) The limited survey information available tended to substantiate the concept that implementing agroforestry practices can help reduce deforestation.


Sellers, P.J., L. Bounoua, G.J. Collatz, D.A. Randall, D.A. Dazlich, S.O. Los, J.A. Berry, I. Fung, C.J. Tucker, C.B. Field, and T.G. Jensen.
"Comparison of Radiative and Physiological Effects of Doubled Atmospheric CO2 on Climate"

The physiological response of terrestrial vegetation when directly exposed to an increase in atmospheric carbon dioxide (CO2) concentration could result in warming over the continents in addition to that due to the conventional CO2 "greenhouse effect". Results from a coupled biosphere-atmosphere model (SiB2-GCM) indicate that, for doubled CO2 conditions, evapotranspiration will drop and air temperature will increase over the tropical continents, amplifying the changes resulting from atmospheric radiative effects. The range of responses in surface air temperature and terrestrial carbon uptake due to increased CO2 are projected to be inversely related in the tropics year-round and inversely related during the growing season elsewhere.


Smith, Amy Tetlow
"Environmental Factors Affecting Global Atmospheric Methane Concentrations"

Methane is a greenhouse gas of largely biological origin. Micro-organisms responsible for production of much of the atmospheric methane are directly affected by climate resulting in potential feedbacks between the atmosphere and the biosphere. Our current understanding of the role of methane in the climate system is reviewed in this article, with a brief discussion of biological, chemical, and physical processes responsible for the spatial and temporal distribution of atmospheric methane. The magnitude of most methane sources is highly speculative, and their distributions are qualitatively understood. Most terrestrial source regions have been surveyed, but few have been studied in much. detail The strength of enteric sources is based on laboratory measurements of emissions from a few animals and estimates of global populations. Accuracy of the resulting flux size and distribution is highly suspect. Data available on either magnitude or distribution of non-biogenic methane sources are scarce. Models of the influence of climate on biological methane sources are primarily regressions dependent on measures of heat and water in the environment. Process-based models derived from biological and physical principals are called for in order to address environmental conditions unlike the present.


Solomon, Susan and John S. Daniel
"Impact of the Montreal Protocol and its Amendment on the Rate of Change of Global Radiative Forcing"

Increases in chlorinated and brominated halocarbons are believed to be responsible for the depletion of stratospheric ozone observed over much of the globe in the past decade or so. Ozone depletion is in turn believed to lead to a negative radiative forcing, tending to cool the stratosphere and the surface. We show that the increasing atmospheric concentrations of ozone-depleting halocarbons and onset of related ozone depletion likely led to a negative forcing of the climate system in the 1980s that slowed significantly the rate of change of total anthropogenic radiative forcing due to the combined effect of all greenhouse gases over that decade. Within the next decade, emissions of these halocarbons are expected to rapidly decrease, with corresponding impacts on ozone and radiative forcing. As the emissions of ozone-depleting gases are reduced and eventually phased out, the rate of ozone depletion is expected to decrease and eventually reverse. All other things being equal, we show that the change from deepening ozone depletion in the 1980s to ozone increases in the future should lead to a pronounced increase in the decadal rate of change of anthropogenic greenhouse forcing of the next few decades, perhaps to levels unprecedented in this century.


Sykes, M. T. and I. C. Prentice
"Boreal Forest Futures: Modelling the Controls on Tree Species Range Limits and Transient Responses to Climate Change"

Range limits and broad-scale geographic variations in the productivity of boreal and northern deciduous tree species in Europe are simulated with a bioclimatic model (STASH). STASH is based on a small number of distinct mechanisms by which climate is thought to affect the survival, regeneration and growth of trees. Survival is limited by summer warmth requirements and winter cold tolerance; regeneration, additionally by winter chilling requirements; and growth rate by net assimilation, which in turn is related to photosynthetically active radiation, growing-season length, temperature (relative to species-specific optima) and soil moisture supply (relative to evaporative. demand) These mechanisms are quantified either as thresholds (for survival and regeneration) or multipliers (for growth), based on bioclimatic variables computed from monthly climate normals interpolated three-dimensionally to a 10-minute grid. Growing-season and growing degree day calculations take into account the effects of chilling. The drought calculations also take into account the effects of soil-moisture storage by means of a physically based evapotranspiration calculation coupled to a one-layer soil hydrology model. STASH is used to examine changes in potential range limits under a 2xCO2 climate-change scenario. Associated transient responses at selected sites in the boreal and boreo-nemoral zones of Sweden are also simulated, using the forest gap model FORSKA2. The species-specific survival and regeneration constraints and growth responses of STASH modify the growth, establishment and mortality of trees in FORSKA2. The results obtained in this way differ sharply from the results of conventional forest gap models, where growth rates are assumed to decline to zero at minimum and maximum growing degree day limits. For example, towards the southern limit of Picea abies (Norway spruce), STASH correctly shows no decline in productivity, but rather an abrupt cut-off corresponding to a chilling requirement during regeneration that is not met further south or west. In transient warming scenarios, this mechanism has the effect that natural regeneration can be blocked due to the warm winters even as yield is increasing due to the longer and warmer summers. STASH predicts drastic changes in species distributions in response to the large climate changes (especially winter warming) expected for northern Europe. Some of the common boreal species (e.g., Picea abies; Pinus sylvestris; Alnus incana are unlikely to survive in much of their present range, withdrawing to the far north. Other species already widespread may be able to occupy some of the few sites that are today unavailable to them (e.g., Betula spp.; Corylus avellana). Other temperate deciduous species such as Gagus sylvaatica could have dramatic range expansions, potentially occupying large tracts of the present boreal zone. FORSKA2 transient simulations illustrate some of the possible routes towards different types of forest in a changed climate. Some sites in the north show little change in species composition, but sites towards the southern boundary of the boreal zone could develop a new suite of dominants. The degree of sensitivity of a particular site depends both on the climate change prediction and on the transient dynamics of the forest community. Many types of transient behaviour are shown to be possible. Coupled with uncertainties about the future role of dispersal and changes in disturbance rate, the complexity and variety of these transient responses imply a highly uncertain future for the north European boreal forests.


Thompson, Russell D.
"The Impact of Atmospheric Aerosols on Global Climate: A Review"

Climate change has received considerable media attention in recent years, particularly in terms of the enhanced greenhouse effect and predicted global. warming This paper examines the alternative impact of atmospheric aerosols on global climate in terms of the so-called dust-veil effect, which is associated with global cooling. This volcanic signal is assessed through the application of dust-rating and explosivity indices, and their limitations are emphasized since both schemes ignore the more important sulphur-gas emissions. The paper discusses the causes and evidence of the volcanic signal and emphasizes its moderation by El Niño events. It concludes with a brief analysis of the contributions made by particulate matter released into the lower troposphere from human activities.


Thornes, John
"Global Environmental Change and Regional Response: the European Mediterranean"

The study of global environmental change should involve geographers in the investigation of regional impacts. Although global changes are important objects of scientific study, their human significance is shaped by the geography of their. impact This depends in turn on spatial and temporal variables at regional and local levels which are the complex outcomes of physical, cultural and socio-economic processes. Compared with the variability imposed by the uncertainty of modelled global scenarios, the spatial variability in regional response is immense. Yet it is this variability of response which must be modelled and predicted. The argument is exemplified with respect to the Old World. Mediterranean


Thornes, John
"Global Environmental Change and Regional Response: The European Mediterranean"

The study of global environmental change should involve geographers in the investigation of regional impacts. Although global changes are important objects of scientific study, their human significance is shaped by the geography of their. impact This depends in turn on spatial and temporal variabilities at regional and local levels which are the complex outcomes of physical, cultural and socio-economic processes. Compared with the variability imposed by the uncertainty of modelled global scenarios, the spatial variability in regional response is immense. Yet it is this variability of response which must be modelled and predicted. The argument is exemplified with respect to the Old World. Mediterranean


Turner, B.L., II, Roger E. Kasperson, William B. Meyer, Kirstin M. Dow, Dominic Golding, Jeanne X. Kasperson, Robert C. Mitchell, and Samuel J. Ratick
"Two Types of Global Environmental Change: Definitional and Spatial Scale Issues in their Human Dimensions"

Clarification of several issues in the human dimensions of global environmental change is essential to the creation of a balanced research agenda. Global environmental change includes both systemic changes that operate globally through the major systems of the geosphere-biosphere, and cumulative changes that represent the global accumulation of localized changes. An understanding of the human dimensions of change requires attention to both types through research that integrates findings from spatial scales ranging from the global to the local. A regional or meso-scale focus represents a particularly promising avenue of approach.


Turner, B.L., II
"Local Faces, Global Flows: The Role of Land Use and Land Cover in Global Environmental Change"

The emergence of land-use and land-cover change (LUCC) as one of the major themes within the global environmental change research community poses a series of difficult but not insurmountable problems. LUCC takes place incrementally through the operation of sets of human and biophysical forces largely specific to the locale in question, but cumulatively LUCC contributes significantly to global environmental change. Linking LUCC to global change requires the cooperation of the natural and social sciences to bridge the local to global dynamics involved. The International Geosphere-Biosphere Programme and the Human Dimensions of Global Environmental Change Programme are undertaking the development of an international research project with such aims in mind. This project seeks to improve understanding of LUCC dynamics by balancing the need for a nuanced understanding at the local level with the need from improved regional and global LUCC models. The rudiments of this effort and some of the problems confronting it are outlined here.


Turner, B.L., II, William B. Meyer, and David L. Skole
"Global Land-Use/Land-Cover Change: Towards an Integrated Study"

Human actions are altering the terrestrial environment at unprecedented rates, magnitudes, and spatial scales. Land-cover change stemming from human land uses represents a major source and a major element of global environmental change Not only are the global-level data on land-use and land-cover change relatively poor, but we need a much better understanding of the underlying driving forces for these changes. Many forces have been proposed as significant, but single-factor explanations of land transformation have proved to be inadequate. How the human causes interact, and under what circumstances each is important, are questions needing systematic research. An international and interdisciplinary agenda is currently being developed to address these issues, through several closely-connected foci of study. A division of the world according to common situations of environment, human driving forces, and land-cover dynamics will be followed by detailed study of the processes at work within each situation. The results will form the basis for a concurrent effort to develop a global land model that can offer projections of patterns of land transformation.


Turner, David P., Greg J. Koerper, Mark E. Harmon, and Jeffrey J. Lee
"A Carbon Budget for Forests of the Conterminous United States"

The potential need for national-level comparisons of greenhouse gas emissions, and the desirability of understanding terrestrial sources and sinks of carbon, has prompted interest in quantifying national forest carbon budgets. In this study, we link a forest inventory database, a set of stand-level carbon budgets, and information on harvest levels in order to estimate the current pools and flux of carbon in forests of the conterminous United States. The forest inventory specifies the region, forest type, age class, productiveity class, management intensity, and ownership of all timberland. The stand-level carbon budgets are based on growth and yield tables, in combination with additional information on carbon in soils, the forest floor, woody debris, and the. understory Total carbon in forests of the conterminous U.S. is estimated at 36. 7Pg, with half of that in the soil compartment. Tree carbon represents 33% of the total, followed by woody debris (10%), the forest floor (6%), and the understory. (1%) The carbon uptake associated with net annual growth is 331 Tg, however, much of that is balanced by harvest-related mortality (266 Tg) and decomposition of woody debris. The forest land base at the national level is accumulating 79 Tg/yr, with the largest carbon gain in the Northeast region. The similarity in the magnitude of the biologically driven flux and the harvest-related flux indicates the importance of employing an age-class-based inventory, and of including effects associated with forest harvest and harvest residue, when modeling national carbon budgets in the temperate zone.


Turner, Monica G. and C. Lynn Ruscher
"Changes in Landscape Pattern in Georgia, USA"

The objectives of this study were to determine how landscape patterns in Georgia, USA have changed through time and whether the spatial patterns varied by physiographic region. Historical aerial photography was used to analyze spatial patterns of land use from the 1930s to the 1980s. Land use patterns were quantified by: (1) mean number and size of patches; (2) fractal dimension of patches; (3) amount of edge between land uses; and (4) indices of diversity, dominance, and contagion. Forest cover increased in aerial extent and in mean patch size. The mean size of agricultural patches increased in the coastal plain and decreased in the mountains and piedmont. Edges between land uses decreased through time, indicating less dissection of the landscape. Fractal dimensions also decreased, indicating simpler patch shapes. Indices of diversity and dominance differed through time but not among regions; the contagion index differed among regions but not through time. A geographic trend of decreasing diversity and increasing dominance and contagion was observed from the mountains to the lower coastal plain. Landscape patterns exhibited the greatest changes in the piedmont region. Overall, the Georgia landscape has become less fragmented and more connected during the past 50 years. Changing patterns in the landscape may have implications for many ecological processes and resources.


Turner, Monica G., Robert V. O'Neill, Robert H. Gardner, and Bruce T. Milne
"Effects of Changing Spatial Scale on the Analysis of Landscape Pattern"

The purpose of this study was to observe the effects of changing the grain (the first level of spatial resolution possible with a given data set) and extent (the total area of the study) of landscape data on observed spatial patterns and to identify some general rules for comparing measures obtained at different. scales Simple random maps, maps with contagion (i.e., clusters of the same land cover type), and actual landscape data from USGS land use (LUDA) data maps were used in the analyses. Landscape patterns were compared using indices measuring diversity (H), dominance (D) and contagion (C). Rare land cover type were lost as grain became coarser. This loss could be predicted analytically for random maps with two land cover types, and it was observed in actual landscapes as grain was increased experimentally. However, the rate of loss was influenced by the spatial. pattern Land cover types that were clumped disappeared slowly or were retained with increasing grain, whereas cover types that were dispersed were lost rapidly. The diversity index decreased linearly with increasing grain size, but dominance and contagion did not show a linear relationship. The indices D and C increased with increasing extent, but H exhibited a variable response. The indices were sensitive to the number (m) of cover types observed in the data set and the fraction of the landscape occupied by each cover type (Pk); both m and Pk varied with grain and extent. Qualitative and quantitative changes in measurements across spatial scales will differ depending on how scale is defined. Characterizing the relationships between ecological measurements and the grain or extent of the data may make it possible to predict or correct for the loss of information with changes in spatial scale.


Turner, Monica G., Virginia H. Dale, and Robert H. Gardner
"Predicting Across Scales: Theory development and Testing"

Landscape ecologists deal with processes that occur at a variety of temporal and spatial scales. The ability to make predictions at more than one level of resolution requires identification of the processes of interest and parameters that affect this process at different scales, the development of rules to translate information across scales, and the ability to test these predictions at the relevant spatial and temporal scales. This paper synthesizes discussions from a workshop on "Predicting Across Scales: Theory Development and Testing" that was held to discuss current research on scaling and to identify key research. issues


Turner, Monica G.
"Spatial and Temporal Analysis of Landscape Patterns"

A variety of ecological questions now require the study of large regions and the understanding of spatial heterogeneity. Methods for spatial-temporal analyses are becoming increasingly important for ecological studies. A grid cell based spatial analysis program (SPAN) is described and results of landscape pattern analysis using SPAN are presented. Several ecological topics in which geographic information systems (GIS) can play an important role (landscape pattern analysis, neutral models of pattern and process, and extrapolation across spatial scales) are reviewed. To study the relationship between observed landscape patterns and ecological processes, a neutral model approach is recommended. For example, the expected pattern (i.e., neutral model) of the spread of disturbance across a landscape can be generated and then tested using actual landscape data that are stored in a GIS. Observed spatial or temporal patterns in ecological data may also be influenced by scale. Creating a spatial data base frequently requires integrating data at different scales. Spatial scale is shown to influence landscape pattern analyses, but extrapolation of data across spatial scales may be possible if the grain and extent of the data are specified. The continued development and testing of new methods for spatial-temporal analysis will contribute to a general understanding of landscape dynamics.


Turner, Monica G.
"Landscape Changes in Nine Rural Counties in Georgia"

Changing patterns of land use/land cover were studied in nine rural counties (Atkinson, Baker, Emanuel, Heard, Monroe, Oglethorpe, Rabun, Tattnall, and Walker) in the state of Georgia from the 1930s through the 1980s. Historical black-and-white aerial photography was analyzed for six 2,116-ha areas in each county during three time periods. Photographs were digitized in raster format (1-ha resolution) using eight land-cover categories: urban, agricultural, transitional, pasture, coniferous forest, upland deciduous forest, lower deciduous forest, and water. Landscape patterns were quantified by using a spatial analysis program written in FORTRAN. Forest increased in overall abundance, and coniferous forest increased in all counties. Transitional lands and lower deciduous forests generally decreased. Agricultural land increased in coastal plain counties but declined in the mountain and piedmont counties. Spatial pattern analyses (number, and mean and maximum size of patches; fractal dimension of patch perimeters; and indices of dominance and contagion) demonstrated that the Georgia landscape is less fragmented than it was in the. 1930s Patches have generally decreased in number and increased in size, although trends in each cover type varied among counties. Changing landscape patterns may have important ecological implications. Information regarding past changes in the rural landscape and the associated effects on ecological processes may be useful in future policy decisions. The linkage of remote sensing and GIS technologies with landscape ecological research can provide a sound basis for assessing broad-scale changes in rural landscapes.


Turner, Monica G. and William H. Romme
"Landscape Dynamics in Crown Fire Ecosystems"

Crown fires create broad-scale patterns in vegetation by producing a patch mosaic of stand age classes, but the spread and behavior of crown fires also may be constrained by spatial patterns in terrain and fuels across the landscape. In this review, we address the implications of landscape heterogeneity for crown fire behavior and the ecological effects of crown fires over large areas. We suggest that fine-scale mechanisms of fire spread can be extrapolated to make broad-scale predictions of landscape pattern by coupling the knowledge obtained from mechanistic and empirical fire behavior models with spatially-explicit probabilistic models of fire spread. Climatic conditions exert a dominant control over crown fire behavior and spread, but topographic and physiographic features in the landscape and the spatial arrangement and types of fuels have a strong influence on fire spread, especially when burning conditions (e.g., fuel moisture and wind) are not extreme. General trends in crown fire regimes and stand age class distributions can be observed across continental, latitudinal, and elevational gradients. Crown fires are more frequent in regions having more frequent and/or severe droughts, and younger stands tend to dominate these. landscapes Landscapes dominated by crown fires appear to be nonequilibrium. systems This nonequilibrium condition presents a significant challenge to land managers, particularly when the implications of potential changes in the global climate are considered. Potential changes in the global climate may alter not only the frequency of crown fires but also their severity. Crown fires rarely consume the entire forest, and the spatial heterogeneity of burn severity patterns creates a wide range of local effects and is likely to influence plant reestablishment as well as many other ecological processes. Increased knowledge of ecological processes at regional scales and the effects of landscape pattern on fire dynamics should provide insight into our understanding of the behavior and consequences of crown fires.


Uitto, Juha I.
"Population, Land Management, and Environmental Change: The Genesis of PLEC within the United Nations University Programme"

PLEC addressed a central issue for sustainable development in the tropical and sub-tropical parts of the world, namely the interlinkages between population processes, land management and environmental change. The programme forms part of the United Nations University programme area entitled 'Sustaining Global Life-Support Systems.' The programme area responds to the United Nations Agenda 21 focusing on selected issues of sustainable development where the University has specific competence. PLEC has strong complementarity with other UNU programmes in this area, including the long-standing programme on 'Mountain Ecology and Sustainable Development'. Close collaboration has also been established between PLEC and the UNU Institute for Natural Resources in Africa (UNU/INRA) based in Ghana, which gives specific backstopping support to the PLEC Clusters in West and East Africa.


Vitousek, Peter M.
"Beyond Global Warming: Ecology and Global Change"

While ecologists involved in management or policy often are advised to learn to deal with uncertainty, there are a number of components of global environmental change of which we are certain-certain that they are going on, and certain that they are human-caused. Some of these are largely ecological changes, and all have important ecological consequences. Three of the well-documented global changes are: increasing concentrations of carbon dioxide in the atmosphere; alterations in the biogeochemistry of the global nitrogen cycle; and ongoing land use/land cover change. Human activity - now primarily fossil fuel combustion - has increased carbon dioxide concentrations from ~ 280 to 355µL/L since 1800; the increase is unique, at least in the past 160,000 years, and several lines of evidence demonstrate unequivocally that it is human-caused. This increase is likely to have climatic consequences-and certainly it has direct effects on biota in all Earth's terrestrial ecosystems.


Walker, Brian H.
"Landscape to Regional-Scale Responses of Terrestrial Ecosystems to Global Change"

The Global Change and Terrestrial Ecosystems (GCTE) project has twin objectives: to predict the feedback effects of changes in terrestrial ecosystems on the atmosphere and climate; and, at a finer scale, the effects of global changes on the structure and function of natural and agro-ecosystems. The main feedback effects are via exchanges of energy, water and momentum, and changes in. biogeochemistry All these processes are affected by ecosystem composition; to obtain a quantitative understanding of the interactions involved, it is necessary to describe vegetation in terms of its functional characteristics, based on a generally applicable classification of plant functional types (PFTs). Global-scale simulations of induced changes in ecosystem composition have progressed from non-dynamic, top-down models to mechanistic, ecophysiological models that predict PFTs and leaf-area index or biomass using plant responses to environmental conditions. Two such models are now being incorporated into general circulation models (GCMs), as first attempts at coupled atmosphere-biosphere. models Parallel developments include global-scale process models, which use fixed vegetation types to predict net primary production and nitrogen cycling, and a bottom-up modeling approach. The latter begins with detailed, mechanistic patch-scale models, extending to spatially variable versions involving landscaped processes and gradually incorporating simplifying routines to allow for large data sets. The many implications of global change for agriculture are illustrated by two examples: