The major impact of climate change in arid and semi-arid Asia is likely to be an acute shortage of water resources associated with significant increases in surface air temperature. Conservation of water used for irrigated agriculture therefore should be given priority attention. With increased evapotranspiration, any adaptation strategy in agriculture should be oriented toward a shift from conventional crops to types of agriculture that are not vulnerable to evapotranspiration (Safriel, 1995). These strategies entail either intensive agriculture in greenhouseswithin which rates of evapotranspiration are much reducedor developing alternatives such as aquaculture that will partly replace agriculture (e.g., fish for human/animal feed, crustaceans for human feed, and unicellular algae for fish/prawn feed, as well as for food additives and medicinal and cosmetic uses). All of these organisms are of high yield; they enjoy solar radiation and often heat, and they do not evaporate or transpire water. Expansion of commercial and artesian fisheries also could help reduce dependence on food productivity. Protection of soils from degradation should be given serious consideration.
Climate change would exacerbate threats to biodiversity resulting from land-use/cover change and population pressure in Asia. Ecosystem services can be impaired by loss of key species in arid and semi-arid Asia (Xiao et al., 1998). Because intraspecies variation in response to environmental stress usually exists in populations subjected to year-to-year climate change, some genotypes in such populations are expected to be more resistant to climate change than others. Such genotypes are more common in peripheral populations than in core populations of species. Although the core population may become extinct because of global warming, resistant types in peripheral populations will survive and can be used to rehabilitate and restore affected ecosystems (Safriel et al., 1994; Kark et al., 1999). The geographic locations of the peripheral species population usually coincide with climatic transition zones, such as at the edges of drylands or along the transition between different types of drylands. Many countries in the region have more than one dryland type and hence should have peripheral populationsespecially in desert and nondesert transitions, which often occur within semi-arid drylands. Identifying regions with concentrations of peripheral populations of species of interest and protecting their habitats from being lost to development therefore can play a role in enhancing planned adaptation for natural and semi-natural ecosystems.
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