Summary of knowledge assessed in the Third Assessment Report

10.1.1 Climate change impacts in Asia

Climate change and variability.

Extreme weather events in Asia were reported to provide evidence of increases in the intensity or frequency on regional scales throughout the 20th century. The Third Assessment Report (TAR) predicted that the area-averaged annual mean warming would be about 3°C in the decade of the 2050s and about 5°C in the decade of the 2080s over the land regions of Asia as a result of future increases in atmospheric concentration of greenhouse gases (Lal et al., 2001a). The rise in surface air temperature was projected to be most pronounced over boreal Asia in all seasons.

Climate change impacts.

An enhanced hydrological cycle and an increase in area-averaged annual mean rainfall over Asia were projected. The increase in annual and winter mean precipitation would be highest in boreal Asia; as a consequence, the annual runoff of major Siberian Rivers would increase significantly. A decline in summer precipitation was likely over the central parts of arid and semi-arid Asia leading to expansion of deserts and periodic severe water stress conditions. Increased rainfall intensity, particularly during the summer monsoon, could increase flood-prone areas in temperate and tropical Asia.

10.1.2 Vulnerabilities and adaptive strategies

Vulnerable sectors. Water and agriculture sectors are likely to be most sensitive to climate change-induced impacts in Asia. Agricultural productivity in Asia is likely to suffer severe losses because of high temperature, severe drought, flood conditions, and soil degradation. Forest ecosystems in boreal Asia would suffer from floods and increased volume of runoff associated with melting of permafrost regions. The processes of permafrost degradation resulting from global warming strengthen the vulnerability of all relevant climate-dependent sectors affecting the economy in high-latitude Asia.

Vulnerable regions. Countries in temperate and tropical Asia are likely to have increased exposure to extreme events, including forest die back and increased fire risk, typhoons and tropical storms, floods and landslides, and severe vector-borne diseases. The stresses of climate change are likely to disrupt the ecology of mountain and highland systems in Asia. Glacial melt is also expected to increase under changed climate conditions. Sea-level rise would cause large-scale inundation along the vast Asian coastline and recession of flat sandy beaches. The ecological stability of mangroves and coral reefs around Asia would be put at risk.

Adaptation strategies. Increases in income levels, education and technical skills, and improvements in public food distribution, disaster preparedness and management, and health care systems through sustainable and equitable development could substantially enhance social capital and reduce the vulnerability of developing countries of Asia to climate change. Development and implementation of incremental adaptation strategies and policies to exploit 'no regret' measures and 'win-win' options were to be preferred over other options. Adaptations to deal with sea-level rise, potentially more intense cyclones, and threats to ecosystems and biodiversity were recommended as high priority actions in temperate and tropical Asian countries. It was suggested that the design of an appropriate adaptation programme in any Asian country must be based on comparison of damages avoided with costs of adaptation.

Advances since the TAR. Aside from new knowledge on the current trends in climate variability and change - including the extreme weather events - more information is now available that confirms most of the key findings on impacts, vulnerabilities and adaptations for Asia. This chapter assesses the state of knowledge on impacts, vulnerabilities and adaptations for various regions in Asia.

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