A broad range of DAFs could be used in principle; to date, however, only a few have been used in practice to provide substantial information to policymakers who are responsible for adaptation decisions at various levels. This subsection lists DAFs that appear to be most relevant for analyzing adaptation decisions. Many DAFs overlap in practice, and clear classification of practical applications sometimes is difficult. The IPCC Guidance Paper on DAFs (Toth, 2000a) provides a more comprehensive, yet incomplete, catalog.
Just as in analyzing decision options for overall climate policy (i.e., at what level should concentrations of GHGs be stabilized, considering the costs and benefits involved?) or for mitigation decisions (timing, location, ways and means of emission reductions), the proper mode to conduct analyses to support adaptation decisions also is sequential decisionmaking under uncertainty and considering future learning. The principal task is to identify adaptation strategies that will take regions or sectors to the best possible position for revising those strategies at later dates in light of new information about expected patterns of regional climate change, socioeconomic development, and changes in climate-sensitive sectors. Consequently, applications of all DAFs in adaptation studies should be formulated in the sequential decisionmaking mode.
The complexities involved in climate change decisionmaking and selecting appropriate
tools to support it stem from the interconnectedness of the various realms of
decisionmaking. Analysts provide advice for setting the global climate policy
target at the global scale; these targets become external constraints when adaptation
strategies are sought at the regional scale that are socially just, environmentally
sustainable, and compatible with regional development objectives.
DAFs that are applicable in adaptation assessments can be distinguished according to whether they rely solely on "desk studies" (involving or not involving formal models) or entail participation of clients, stakeholder groups, or others. Model-based DAFs tend to focus primarily on structuring the problem, apply convenient simplifications, and find efficient solutions to the problem. Participatory DAFs, in contrast, can better accommodate diverse views on climate change impacts and often conflicting interests and options to restrain them. Insights from both kinds of studies are crucial for policymakers to craft effective and broadly acceptable policies.
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