The Regional Impacts of Climate Change

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11.4. Integrated Assessment of Potential Vulnerabilities and Impacts

Individual countries, regions, resources, sectors, and systems will be affected by climate change not in isolation but in interaction with one another. The direct effects of climate change to which this chapter alludes, such as changes in rice crop yields and inundation of coastal areas, will have further indirect effects.

Integration of impacts and adaptations to climate change can take many forms. Several different approaches can be considered for Tropical Asia, including the following:

  1. Country-Specific Studies-These studies have attempted to summarize salient aspects of vulnerability, impacts, and adaptations, generally in a qualitative manner. Some simple examples for India, Indonesia, Malaysia, and Thailand are given in Section 6.5 of the Working Group III contribution to the SAR (IPCC, 1996) and in ADB (1994a, 1994b). In these and other national studies, the conclusions usually are strongly thematic or sector-based.
  2. Geographical Integration-Linkages between different functional regions are difficult to investigate although, at a conceptual level, they are readily acknowledged. For example, drainage basins can provide functional links between climate change impacts in headwaters and the downstream areas they affect; at the same time, however, downstream areas also may be responding to locally specific climate change impacts. Some simple examples have been described in this chapter (e.g., Section Functional adaptations-such as through total river catchment analyses or integrated coastal management-are extraordinarily difficult to implement because of jurisdictional sensitivities, even though conceptual and methodological hurdles may be relatively easy to overcome.
  3. Sectoral and Trade Integration-There have been a number of attempts to integrate the various components of food supply (agriculture) in Tropical Asia, generally with simplified production change models in response to changes in environmental conditions (e.g,. temperature or precipitation and their derivatives, such as length of growing season and time of fruiting), some with yield adaptations and some without. These results are then integrated into an international trade-conditions model, and estimates of net economic welfare impacts are calculated. Reilly et al. (1993) have done this for Tropical Asia using three GCMs and 2xCO2 equilibrium scenarios.
  4. Comprehensive Monetary Estimates-Another way of integrating the range of potential impacts of climate change is to derive a comprehensive monetary estimate, which adds all of a country's impacts, expressed in their dollar value. Expressing damage to marketed goods and services (e.g., land lost to sea-level rise, energy savings in winter) in monetary terms is more or less straightforward because the price is known. Expressing damage to nonmarketed goods and services (e.g., wetland loss, mortality changes) in monetary terms can be done either through examining market transactions where such goods or services are implicitly traded (e.g., tourism, where landscape beauty is valued) or through interviewing people to determine their preferences (i.e., their willingness to pay to secure a benefit or their willingness to accept compensation for a loss). Such valuation techniques reflect economic circumstances and value systems in the Organisation for Economic Cooperation and Development (OECD). The estimates for non-OECD countries in Chapter 6 of the Working Group III contribution to the SAR (IPCC, 1996) are based on extrapolation from studies in the OECD. With these caveats in mind, Chapter 6 of the WG III contribution to the SAR (IPCC, 1996) reports best estimates for the annual impact resulting from a doubling of atmospheric concentrations of CO2 of about 2.1-8.6% of GDP in South and Southeast Asia. These figures compare with an estimated world impact of 1.4-1.9% of GDP. Many assumptions underlie these best guesses, however, and large uncertainties remain.

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