The Regional Impacts of Climate Change

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11.3. Vulnerabilities and Potential Impacts

11.3.1. General Comments

This section discusses impacts that could plausibly result from projected climate changes. In many studies relevant to Tropical Asia, however, specific scenarios are not identified; in several cases, assumptions also have been made about the magnitude and timing of potential climate changes. Four other points are of special relevance. First, climate change represents an important additional external stress on the numerous ecological and socioeconomic systems in Tropical Asia that already are adversely affected by air, water, or land pollution, as well as increasing resource demands, environmental degradation, and nonsustainable management practices. Second, most of Tropical Asia's ecological and socioeconomic systems are sensitive to the magnitude and the rate of climate change. They also have developed a resilience through their long history of adaptation to environmental and cultural changes; identifying resilient features is a particular challenge. Third, Tropical Asia's physical environment is extremely diverse, and traditional systems of land use are very closely adapted to these conditions. Such diversity has important implications for assessing the impacts of future climate change, which would vary greatly from area to area, depending not only on the climate change scenario but also on specific local conditions and changes in factors such as population and technology. Finally, the potential impacts of climate change in Tropical Asia rarely have been quantified. Thus, the results of impact studies usually are qualitative and often have been directed toward identifying the sensitivities of specific systems or sectors. In this regard, considerable progress has been made in recent years in assessing the sensitivity and vulnerability of some ecosystems, activities, resources, and environments in the region. This progress is illustrated by the following discussion. Figure 11-3 summarizes the potential impacts of some of the components of climate change in Tropical Asia.

Figure 11-3: Possible climate change-related impacts in Tropical Asia (+ = projected increase, - = projected decrease).

11.3.2. Ecosystems and Biodiversity

Tropical Asia is rich in natural and managed (crop-related) biodiversity. The richness in terrestrial and coastal ecosystems can be gauged from the following facts:

In both cases, however, habitat loss and degradation have reached acute levels (UNEP, 1997).

Potential climate change-related impacts are highlighted in the following examples, along with other types of human-related impacts. Terrestrial Ecosystems Tropical forests

Forests are extremely sensitive to climate change, as well as to other stresses. Section 1.4 of the Working Group II contribution to the SAR (IPCC, 1996) concludes that tropical forests are likely to be more affected by changes in land use than by climate change, as long as deforestation continues at its current high rate; that any degradation of these forests, whether it is caused by climate or land-use changes, will lead to an irreversible loss in biodiversity; and that tropical forests are likely to be more affected by changes in soil water availability (caused by the combined effects of changes in temperature and rainfall) than by changes in temperature per se.

Details on the potential impacts of climate change on the forests of Tropical Asia are provided in Section

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