The Regional Impacts of Climate Change

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1.1. Scope of the Assessment

Worldwide concern about possible climate change and acceleration of sea-level rise resulting from increasing concentrations of greenhouse gases has led governments to consider international action to address the issue, particularly through the development of the United Nations Framework Convention on Climate Change (UNFCCC). Because the extent and urgency of action required to mitigate the source of the problem-namely the emission of greenhouse gases by human activities-depends on the level of vulnerability, a key question for the Conference of the Parties (COP) to the Convention, and for policymakers in general, is the degree to which human conditions and the natural environment are vulnerable to the potential effects of climate change. Impact assessments are needed to establish the costs and benefits of climatic change as a guide to what adaptation and mitigation measures might be justified. Without such assessments, we run the risk of making uninformed, unwise, and perhaps unnecessarily costly decisions.

The foundation for policy formulation for the climate change problem is scientific information on greenhouse gas emissions, the climate system and how it may change, and the likely impacts on human activities and the environment. To provide the best available base of scientific information for policymakers and public use, governments have requested that the Intergovernmental Panel on Climate Change (IPCC) periodically assess and summarize the current scientific literature related to climate change. The most recent assessment is the Second Assessment Report (SAR), a comprehensive three-volume report completed in 1995 and published in 1996. This assessment involved extensive inputs from thousands of scientists and was reviewed by governments and leading experts. The SAR takes a global view of the impacts of climate change, organizing chapters by ecosystem type or socioeconomic sector (e.g., forests, grasslands, agriculture, and industry).

In making use of the SAR, the UNFCCC negotiators found a need for more explicit information on how different regions of the world might be affected, to better assess their degrees of vulnerability. Accordingly, the Subsidiary Body for Scientific and Technological Advice (SBSTA) of the UNFCCC requested that the IPCC prepare a report that provided a geographically explicit view of the problem, particularly the vulnerabilities for each region. Initially, a Technical Paper was planned (which, under the IPCC rules of procedure, limited the authors to citing only material included in the SAR), but in September 1996 the IPCC XIIth Plenary at Mexico City decided that a Special Report should be produced. This decision was taken to allow the inclusion and proper review of new material post-dating the SAR-especially new work emerging from several country studies programs, as well as regional studies which were not included in the SAR due to its global scope.

The present report is the result of this process. This report provides assessments of vulnerability of climate change for 10 regions of the globe: Africa, the Arctic and the Antarctic (Polar Regions), Australasia, Europe, Latin America, Middle East and Arid Asia (Arid Western Asia), North America, Small Island States, Temperate Asia, and Tropical Asia. It also includes several annexes that provide information about climate observations, climate projections, vegetation distribution projections, and socioeconomic baseline assumptions used in the report.

1.2. Approach of the Assessment

This report should be read as an assessment of the scientific and technical literature related to the sensitivity, adaptability, and vulnerability of ecosystems and social and economic sectors in the 10 regions-not as a quantitative integrated assessment of impacts. The approach used in preparing the assessment was agreed by the lead authors at a series of scoping meetings held in Washington, DC, in May and September 1996, which set the direction of the assessment when it was being prepared as a technical paper. These meetings were used to review materials from the sectoral assessments of the SAR and organize them into regional analyses, and to identify common issues across the regions and standardize approaches to addressing them. After the paper was reprogrammed as a special report, a series of chapter-specific regional consultations and meetings of lead authors and other experts was held to refine the scope of each regional assessment and to identify studies and methods to use in addition to those used in the SAR. These meetings were held in Toronto, Canada (13-15 January 1997); New Delhi, India (23-25 January 1997); Harare, Zimbabwe (27-29 January 1997); Tarawa, Kiribati (10-13 February 1997); Montevideo, Uruguay (11-13 February 1997); and Amsterdam, The Netherlands (19-21 March 1997).

On the basis of these meetings, the lead authors set about preparing each chapter to provide an assessment of the vulnerability of natural ecosystems, socioeconomic sectors, and human health in the region. The definition of vulnerability used in the SAR was adopted for use by the lead authors in this report: "Vulnerability" is the extent to which climate change may damage or harm a system; it is a function of both the "sensitivity" of a system or structure to climate and the opportunities for "adaptation" to new conditions. Sensitivity is defined as the degree to which a system will respond to a change in climatic conditions (e.g., the extent of change in ecosystem composition, structure, and functioning, including primary productivity, resulting from a given change in temperature or precipitation). The responses may result in either beneficial or harmful effects. Adaptation is defined as adjustments in practices, processes, or structures in response to projected or actual changes in climate. Adjustments can be either spontaneous or planned, reactive or anticipatory. In some cases (e.g., for many ecosystems), options for planned or anticipatory adaptation may not exist. Adaptations can reduce negative impacts or take advantage of new opportunities presented by changing climate conditions. It is in part because of the uncertainties associated with regional projections of climate change (these uncertainties are summarized in Section 1.3.2. and described more fully in Annex B) that this report takes the approach of assessing vulnerabilities, rather than quantitatively assessing expected impacts of climate change.

This report is based upon evidence found in the published literature, which uses a diverse range of methods and models. This diversity reflects current uncertainties regarding the functioning of complex natural and social systems and how they respond to changes in climate. The assessment did not include the performance of new research or computer model simulations by the authors to estimate impacts under common scenarios of greenhouse gas emissions or climate change. Such work was beyond the scope of the report. Because the available studies have not employed a common set of climate scenarios, and because of uncertainties regarding the sensitivity and adaptability of natural and social systems, the assessment of regional vulnerabilities is necessarily qualitative. Often only very general conclusions can be supported by the currently available evidence. In a number of instances, quantitative estimates of impacts of climate change are cited in the report. Such estimates are strongly dependent upon the specific assumptions made and models used. These estimates should not be interpreted as predictions of the most likely impacts, but rather as illustrations of the potential character and magnitude of impacts that may result from specific scenarios of climate change.

Many impacts studies use model simulations for the equilibrium climatic response to a carbon dioxide (CO2) doubling, rather than more recent model simulations of climate change resulting from gradually increasing CO2 concentrations and changing concentrations of aerosols and stratospheric ozone. Thus the level of warming used in many of the impacts studies may not be reached until several decades after 2100, rather than by that date. However, this does not necessarily mean that all impacts will be slowed; for example, the transient simulations exhibit larger land-sea temperature change contrasts, and this would be expected to alter atmospheric circulation and weather patterns in ways not predicted in the equilibrium simulations. Historical observations of the impacts of weather patterns-including droughts, floods, storms, and other extreme weather events-suggest that changes in climate variability could have important impacts on natural and social systems.

Some readers of the special report will be interested only in a particular region, whereas others will be interested in comparing information from different regions. To facilitate such comparison, a common structure, or template, for each regional chapter was developed. The main elements of this chapter template follow:

Executive Summary

Regional Characteristics

Sensitivity, Adaptability, and Vulnerability

Integrated Assessment of Potential Impacts

This approach is broadly consistent with the seven-step method outlined by the IPCC in its Technical Guidelines for Assessing Climate Change Impacts and Adaptations (IPCC, 1994b). These steps are: 1) defining the problem; 2) selecting the method; 3) testing the method/sensitivity; 4) selecting scenarios; 5) assessing biophysical/socioeconomic impacts; 6) assessing autonomous adjustments; and 7) evaluating adaptation strategies.


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