The Regional Impacts of Climate Change

Other reports in this collection Mountain Regions

Although most of the region is relatively flat, mountains (e.g., Hindu Kush, Karakoram, and Tien Shan) exist in the eastern part. Afghanistan, Kazakstan, Pakistan, Tajikistan, and Uzbekistan all have mountains of up to 5,000 m; the highest point in the region is Communism Peak in Tajikistan. The Kazak uplands in Kazakstan reach 1,560 m. Much of the Arabian peninsula has upland areas of 1,000-2,000 m, and some areas in Yemen and Oman reach 3,700 m and 3,000 m, respectively. Areas in western Pakistan are above 2,000 m, and the uplands in Iran and Turkey reach 2,000 m and 3,000 m, respectively. Countries with very few or no uplands (i.e., areas above 500 m) include Iraq, Kuwait, and the United Arab Emirates.

In this arid region, the mountainous areas are wet, cool, and hospitable for human dwelling and commercial cultivation. Human encroachment in mountain regions has reduced vegetation cover, which has increased soil-moisture evaporation, erosion, and siltation-with adverse effects on water quality and other resources (IPCC 1996, WG II, Section 5.1.5).

Some mountains in the region have permanent glaciers that will be affected by climate change. There will be pronounced alterations in glacier-melt runoff as climate warms in the region. Glaciers will provide extra runoff as ice melts. In most mountain regions, this increase in runoff will last for a few decades, then decrease as the glaciers disappear. For countries with very large glaciers, the extra runoff may persist for a century or more and substantially increase regional water resources. Tentative estimates have been made for central Asia, based on mass balances from a small number of Tien Shan glaciers for the period 1959-1992 (IPCC 1996, WG II, Section 7.4.2). Extrapolation to the whole of central Asia suggests that glacier mass has decreased by 804 km3 over that time, representing a 15% increase in glacial runoff.

A decrease in snowfall and glacier ice would influence the seasonality of river flow by reducing the production of meltwater in the warm season. The expected smoothing of the annual runoff amplitude could be beneficial (e.g., energy production in winter, reduction of summer flood peaks) and detrimental (e.g., reduced water supply for summer irrigation in dry areas). As mountain glaciers begin to disappear, the volume of summer runoff eventually will be reduced as a result of loss of ice resources. Consequences for downstream agriculture, which relies on this water for irrigation, will be unfavorable in some places. For example, low- and mid-lying parts of central Asia are likely to change gradually into more-arid, interior deserts (IPCC 1996, WG II, Section 7.5.1).

In parts of central Asia, regional increases in temperature will lead to an increased probability of events such as mudflows and avalanches that could affect human settlements (Iafiazova, 1997).

Other reports in this collection