The adaptive capacity of a resource system or a human society depends on the resilience of these systems. Resilience in the face of climate change, as with resilience to present-day hazards such as floods and droughts, therefore depends on the scale, intensity, and rate of change of the climate system, as well as the inherent ability of ecosystems or communities to adjust to new circumstances (Riebsame et al., 1995). Resilience is the ability of a system to return to a predisturbed state without incurring any lasting fundamental change. Resilient resource systems recover to some normal range of operation after a perturbation. The processes of short-term adjustment to changes in land productivity and food scarcity in traditional societies of Asian countries are resilient to perturbations. This resilience has been demonstrated in a range of resource systems throughout Asia, including highland agriculture, large-scale irrigated agriculture, and fishery-dependent communities (e.g., Bray, 1986; Bayliss-Smith, 1991; Tang 1992; Grove et al., 1998; Ruddle, 1998; Adger, 1999a). Long-term adaptation to climate change requires anticipatory actions, which would require considerable investment of capital, labor, and time hence diversion from scarce available resources, existing services, and infrastructure. Constraints on such resources clearly are more acute in the developing countries of Asia. The three crucial sectors of land resources, water resources, and food productivity are of highest priority for planned adaptation, particularly for the poorer resource-dependent countries.

Adaptation to climate change in Asian countries depends on the real cost of adaptive measures, the existence and engagement of appropriate institutions, access to technology, and biophysical constraints such as land and water resource availability, soil characteristics, genetic diversity for crop breeding (e.g., development of heat-resistant rice cultivars), and topography. Demand for land and water already is increasing to support growing populations, increased agricultural activities, and expanding modern urban infrastructure. Most developing countries in Asia face significant impacts from present-day climatic hazards. Faced with impending floods, the economic insecurity of communities and rural households, lack of timely warnings, ignorance of the severity of danger from flood, and lack of efficient transport systems, some developing countries of Asia often choose not to evacuate homes to avoid climate-related disasters. Such circumstances also act as constraints for the alleviation of poverty and hence reinforce social vulnerability. For many developing countries in Asia, climate change is only one of a host of environmental problems; these countries have to individually and collectively evaluate the tradeoffs between climate change actions and nearer term needs (such as food security, air and water pollution, and energy demand). Adaptation measures designed to anticipate the potential effects of climate change can help to offset many of the negative effects (Burton, 1997). Adaptation measures that ameliorate the impacts of present-day climate variability include sea defenses, institutional adaptations, plant breeding, and adoption of new technologies in agriculture. Many countries in Asia already commit significant resources to ameliorating climate-related hazards (e.g., Golubtsov et al., 1996; Nishioka and Harasawa, 1998; Ali, 1999; Huq et al., 1999).

Development and broad application of integrated modeling efforts (those that consider interactions of biophysical and socioeconomic factors) and modeling approaches that are particularly applicable at the regional scale warrant increased attention. For example, mountain systems in Asia are vulnerable with respect to ecological and social systems, for reasons of high heterogeneity. Management of Asia's mountain landscape therefore demands diversified strategies that link ecological and social components for location-specific solutions (Ehrenfeld, 1991; Ramakrishnan, 1992). Inclusion of complex feedbacks between systems may change significantly the current "mean" estimate of impacts.

Sustainable development within Asia's agroecosystems is crucial to provide adequate food security for traditional farming communities in the lowlands and the uplands in developing countries and to ensure in situ conservation of crop biodiversity for sustaining high-input modern agriculture itself. However, conserving biodiversity with concerns for higher production from these complex agroecosystems is a challenging task, for which novel development alternatives are required (Ramakrishnan, 1992; Ramakrishnan et al., 1996; Swift et al., 1996). Traditional societies have always manipulated biodiversity to ensure ecosystem resilience and to cope with uncertainties in the environment, rather than to increase production on a short-term basis. There is increasing evidence now to suggest that we could learn from their traditional ecological knowledge base (Gadgil et al., 1993) for coping with uncertainties associated with global change.

The resilience of agricultural practices in the face of climate change depends on the nature and magnitude of region-specific climate change, regional sensitivity, or the threshold and social resilience and adaptive capacity of agricultural communities. Adjustment of planting dates to minimize the effect of temperature increase-induced spikelet sterility can be used to reduce yield instability, for example, by avoiding having the flowering period to coincide with the hottest period. Adaptation measures to reduce the negative effects of increased climatic variability may include changing the cropping calendar to take advantage of the wet period and to avoid extreme weather events (e.g., typhoons and storms) during the growing season. Crop varieties that are resistant to lodging (e.g., short rice cultivars) may withstand strong winds during the sensitive stage of crop growth. A combination of farm-level adaptations and economic adjustments such as increased investment in agriculture infrastructure and reallocation of existing land and water resources would be desired in the agriculture sector. Increasing demand for water by competing sectors may limit the viability of irrigation as a sustainable adaptation to climate change. Expansion of irrigation as a response to climate change will be difficult and costly in many of the countries in Asia even under favorable circumstances. Mounting societal pressures to reduce environmental degradation will likely foster an increase in protective regulatory policies, further complicating adaptations to climate change (Easterling, 1996).

A commonly prescribed adaptation to climate change in the water sector is to enhance characteristics that offer flexibility hence enhancing resilience. Flexibility issues are particularly important with regard to the development of water resources for industry or agriculture. Major projects such as dams actually may limit flexibility if they lose effectiveness as regional hydrological water balances undergo major changes. With likely changes in climate variability, dams and sea defenses built to withstand a 100-year extreme event may not be adequate thus leading to a risk of major catastrophe. If hydrological patterns change markedly and irrigated agriculture is required to relocate in response, prior investments may be lost as existing infrastructures become obsolete, and additional investments will be needed. This necessitates critical scrutiny of a range of available choices that incorporate economic and environmental concerns. The potential for adaptation should not lead to complacency (Rosenzweig and Hillel, 1995). Some adaptive measures may have detrimental impacts of their own.

The issue of natural resource management in Asia has a highly complex set of interconnections between natural and social systems. Natural resource management in largely rural tropical environments must reconcile ecological and social processes that operate at a range of scales, from species up to the landscape level. Studies have shown that ecologically important keystone species often are socially selected by many rural societies (Jodha, 1996). The possibility for species selection for rehabilitating a degraded ecosystem should be based on a value system that the local people understand and appreciate; therefore, their participation in the process of developmental activity is important. Community perceptions of soil and water management can be a powerful agent for sustainable management of natural resources (e.g., in the case of highly fragile and vulnerable Himalayan mountain systems) (Ramakrishnan et al., 1994). In other words, natural resource management in tropical Asia must be sensitive to social and even cultural perceptions (Ramakrishnan, 1998), as well as traditional resource management practices.

Major fishery-related environmental issues include the effects of trawling on sea-bottom habitats and the detrimental effects of catches of nontarget species on populations and ecosystems. Fishery resources also are threatened by activities other than commercial fishing. Loss of inshore fish nursery habitats from coastal development and pollution from land-based activities cause significant change to ecosystems that support fisheries. Effective conservation and sustainable management of marine and inland fisheries are needed at the regional level so that living aquatic resources can continue to meet regional and national nutritional needs. Asian economic growth has failed to alleviate poverty for a large share of Asian people to date. Achieving economic and industrial growth in Asia that is sustainable—both ecologically and economically viable over the long term—would require more than just cleaner, more efficient industrial processes; it demands a reorientation toward becoming less material-intensive and attempting to contribute toward protecting our environment and ecosystem.

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