One way of expressing the potential impacts of climate change is to derive a comprehensive monetary estimate, which sums all known impacts and is expressed as a monetary value. Estimating effects on marketed goods and services (e.g., commercial or residential land loss resulting from sea-level rise, energy savings in winter) in monetary terms is relatively straightforward because the prices are known. Estimating damage to nonmarketed goods and services (e.g., wetland loss, mortality changes) in monetary terms is possible either through examining market transactions where such goods or services are implicitly traded (e.g., sites of landscape beauty) or through interviewing people to determine their preferences (i.e., their willingness to pay to secure a benefit or willingness to accept compensation for a loss). In Organisation for Economic Cooperation and Development (OECD) countries, such valuation techniques are relatively well established and have been widely applied, although the results often are contentious. Estimates for non-OECD countries are based on extrapolation from studies in the OECD. The best estimate of the annual impact of a doubling of the CO2 concentration in the atmosphere is about 0.9-5.5% of GDP for the Middle East, compared with 1.4-1.9% of GDP for the world. Many assumptions underlie these best guesses, however, and large uncertainties remain. Nevertheless, the impact on this region appears to be greater than that on the world as a whole (Fankhauser and Tol, 1977).
The countries of the FSU are undergoing radical economic transitions, with great impacts on many sectors likely to be affected by climate change. Much of the agriculture of the Middle East and Arid Asia region developed in response to the agricultural plans of the FSU. Irrigated cotton production, for example, expanded from the 1960s through the 1980s, with significant impacts on water resources, the environment, and human health. Water resources were overcommitted to agriculture and were transferred unsustainably from several river systems. The drying of the Aral Sea (see Section 7.4.2) was one consequence; the salinization of many cropping areas was another. The heavy use of fertilizers and overuse of pesticides has left a legacy of polluted soils and water supplies. Recent assessments (World Bank, 1995a-d) conclude that agricultural practices are likely to change because agricultural products now are being traded on world markets. Changes include more targeted use of fertilizers, better use of integrated pest management, more efficient irrigation systems in existing systems, and changes in crop species and varieties. These changes will dominate policy development in this region, but they also offer opportunities to adapt to climate change by reducing water use and adopting new crop varieties.
In particular, targets for improved efficiency in irrigation could lead to savings in water use, which would be more important than any changes likely to result from climate change over the next few decades. Throughout the states of the FSU, options to reduce water use include lining more irrigation canals to reduce seepage losses (up to 40% of diverted water is lost in arterial channels) and reducing the area of crop and pasture irrigated by inefficient flooding methods while increasing the area of more-valuable fruit and vegetable crops irrigated by efficient drip and below-ground irrigation systems. In Turkmenistan, for example, cotton irrigation currently requires 12,000 m3 water/ha; more modern techniques would require only 7,000 m3/ha (World Bank, 1995a-d). More than one-third of all water used in Turkmenistan is applied to irrigated cotton; thus, modernizing techniques could save 20% of the country's current water use. Uzbekistan plans to reduce water consumption in agriculture by 20% during 1990-2005, and similar opportunities for such large savings probably apply in Tajikistan.
In many countries of the FSU, there also has been a decrease in pressure on the environment. These effects are apparent in the case of water resources, as well as in other sectors; for example, the total livestock population in Kazakstan (many existing in rangelands) decreased by 50% between 1990 and 1996 (Mizina et al., 1997).
No integrated assessments have been carried out on the impacts of human activity and climate change on the natural, economic, or social systems of the region. However, the recent history of the Aral Sea may serve as an illustrative case study of some of the multiple factors involved and the multiple effects that are likely to result.
The Aral Sea is a dramatic example of how inappropriate human activities-exacerbated by adverse impacts of climate change-can affect natural ecosystems and coastal systems, water supply, food production, human settlements, and human health (Popov and Rice, 1997). Since 1960, extensive irrigation development projects and intensive use of agricultural chemicals have resulted in regional environmental deterioration. The water level has dropped 16 m since 1960, and the open-water area has decreased by almost 50%. In the past 36 years, the Aral coastline has retreated by 50-100 km (Schreiber and Shermuchamedov, 1996). Schreiber and Shermuchamedov have detailed the resulting degradation in the region and suggested some measures to minimize the effects.
Surface water resources of the Aral basin originate from several large river basins; the most important are the Amudaria and Syrdaria basins. A period of low precipitation, which has reduced the flow of river water, has caused a 26% decrease in the water level of the Aral Sea. Runoff water regulations and intensive use of irrigation water for cotton and rice, along with the inflow of polluted water (i.e., sewage, industrial effluent, and mineralized pollutants) into the rivers, has changed the historic function of the Aral Sea, which used to be the main water and salt accumulation basin for Middle Asia. Currently, the waters of the Amudaria and Syrdaria Rivers are used primarily for irrigation; runoff into the Aral Sea has practically halted. Regulation of river runoff and its extensive use for irrigation also have caused dramatic changes in the rivers' hydrological regimes.
General degradation of floodplain and delta soils has taken place in the region since river flow regulations were implemented. The drying off process and subsequent desertification and salinization of soils have accelerated, resulting in an observed temperature increase of 1.5�C within 100-150 km of the edge of the sea. The process of desertification is accompanied by significant losses of soil organic matter (through wind erosion), particularly in marsh soils. The water in the main rivers of the region is contaminated by salts; other pollutants, such as nitrates, pesticides, organic and oil products; and increased bacterial contaminants and is not presently acceptable for drinking or irrigation use. The social, economic, and ecological consequences of the Aral Sea catastrophe are extensive: The infant mortality rate in the area is 46 deaths per 1,000 live births, and 80% of all human diseases in the region near the Aral Sea have been linked directly with drinking polluted water. The changes also are leading to a major loss of biodiversity of the region (Bie and Imevbore, 1995).
Because water is such a valuable resource in the area and affects all ecosystems-as well as human food and fiber production and health-it will have to be managed carefully to reduce the catastrophic and possibly long-term negative impacts in situations such as those illustrated by the Aral Sea. Several protective measures have been implemented in the area, especially to reduce wind erosion (which has decreased in recent years). Water quality monitoring, pollution control, and water protection zones have been set up in an attempt to minimize some of these effects.
Nissenbaum (1994) provides a similar reconstruction of rapid environmental degradation and impacts on the surrounding population-in an account of the collapse of the cities of the southern basin of the Dead Sea 4,000 years ago.
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