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The Middle East and Arid Asia includes 21 countries of the predominantly arid and semi-arid region of the Middle East and central Asia. The region extends from Turkey in the west (26�10'E) to Kazakstan in the east (86�30'E) and from Yemen in the south (12�40'N) to Kazakstan in the north (50�30'N). Although the relief is mostly low, there are several peaks of 7,500 m or more in the Hindu Kush and Tien Shan mountain ranges; the lowest point is the Dead Sea in Israel (-395 m). Many of the region's countries are landlocked. The total population is 433 million, with half living in urban centers; six of the 21 countries have urban populations of over 80%. Countries of the region vary greatly in gross national product (GNP)-they include relatively resource rich, oil exporting countries and several poorer countries.
Climate: Average monthly mean daily temperatures in the region range from -10�C to 25�C in January to 20�C to >35�C in July. The rainfall in the region is low but highly variable. Average monthly rainfall ranges from 0 mm to 200 mm in January and from 0 mm to 500 mm in July.
Climate trends: Records of annual temperatures during the period 1900-96 show almost no change for most of the Middle East region, but a 1-2�C/century increase for central Asia. There was a 0.7�C increase from 1900 to 1996 for the region as a whole. There was no discernible trend in annual precipitation during 1900-95 for the region as a whole, nor in most parts of the region-except in the southWestern part of the Arabian peninsula, where there was a 200% increase. This increase, however, is in relation to a very low base rainfall (<200 mm/yr).
Climate scenarios: Climate models project that temperatures in the region will increase by 1-2�C by 2030-2050, with the greatest increases in winter in the northeast and in summer in part of the southWest. Precipitation is projected to increase slightly in the winter throughout the region and in the summer to remain the same in the northeast and increase in the southWest (i.e., the southern part of the Arabian peninsula). These precipitation projections vary from model to model and are unlikely to be significant. Because of projected increases in temperatures, higher evaporation is expected. Soil moisture is projected to decrease in most parts of the region, which may lead to increased areas of soil degradation.
Because of the arid nature of the region, some sectors will be particularly affected by climate change. The impacts on these sectors are summarized below.
Ecological systems: The region is mostly arid and semi-arid and is dominated by grasslands, rangelands, deserts, and some woodlands. Vegetation models project little change in most arid (or desert) vegetation types under climate change projections. The impacts may be greater in the semi-arid lands of the region than in the arid lands, especially in composition and distribution of vegetation types. The projected small increase in precipitation is unlikely to improve land conditions in the next century, partly because soil conditions take a long time to improve and partly because human pressure on these systems may contribute to land degradation. Improved water-use efficiency by some plants under elevated carbon dioxide (CO2) may lead to some improvement in plant productivity and changes in ecosystem composition. Grasslands, livestock, and water resources are likely to be most vulnerable to climate change in this region because they are located mostly in marginal areas. Management options, such as better stock management and more integrated agroecosystems, could improve land conditions and counteract pressures arising from climate change.
Forests/woodlands are important resources, although they cover only a small area. They will have to be safeguarded, given the heavy use of wood for fuel in some countries.
The region has a large area dominated by mountains, such as the Hindu Kush, Karakoram, and Tien Shan mountains in the eastern part of the region. Mountain areas are under pressure from human use, which is leading to land degradation in some areas. Some of the mountains have permanent glaciers, which will be affected by climate change. Glacial melt is projected to increase under climate change, leading to increased flows in some river systems for a few decades; this will be followed, however, by a reduction in flow as the glaciers disappear-creating larger areas of arid, interior deserts in low- and mid-lying parts of central Asia.
A tenth of the world's known species of higher plants and animals occur in this region. Many countries are centers of origin for crop and fruit tree species of critical importance to world food production; thus, they are important sources of genes of wild relatives. Few studies have assessed the impact of climate change on biodiversity in the region. Current human activity, however, is causing a loss of biodiversity.
Water resources: Water shortages already are a problem in many countries of this predominantly arid region, and are unlikely to be reduced and may be exacerbated by climate change. Projected precipitation increases are small, and temperatures and evaporation are projected to rise. Rapid development is threatening some water supplies through salinization and pollution, and expanding populations are increasing the demand for water. Adaptation strategies might include more efficient organization of water supply, treatment, and delivery systems for urban areas and, in arid Asia, increased use of groundwater. Measures to conserve or reuse water already have been implemented in some countries; such strategies may overcome some shortages, especially if they are adopted widely throughout the region. Changes in cropping practices and improved irrigation practices could reduce water use significantly in some countries, especially those of the former Soviet Union (FSU).
Food and Fiber: Land degradation problems and limited water supplies constrain present agricultural productivity and threaten the food security of some countries. Though there are few projections of the impacts of climate change on food and fiber production for the region, studies in Kazakstan and Pakistan have suggested some negative impacts on wheat yields. There are also projected increases (e.g., winter wheat in Kazakstan). Many of the options available for combating existing problems will contribute to reducing the anticipated impacts of climate change. Food and fiber production concentrated on more intensively managed lands could lead to greater reliability in food production and reduce the detrimental impacts of extreme climatic events, such as drought, on rangeland systems. Implementation of more flexible risk-management strategies (e.g., long-term and appropriate stocking rates, responding to variations in precipitation by changing animal numbers annually)-along with the use of a wider variety of domestic animals, game ranching, and multiple production systems-would provide greater food security to the region.
Health: Human health in the region is variable, reflecting the economies of the countries. Some countries, where poverty is high, have high infant mortality rates and low life expectancies. The impacts of climate change are likely to be detrimental to the health of the population, mainly through heat stress and possible increases in vector-borne (e.g., dengue fever and malaria) and waterborne diseases. Decreases in water availability and food production (especially if there is a shortage of water for irrigation) would lead to indirect impacts on human health associated with nutritional and hygiene issues.
Integration: Countries of the FSU are undergoing major economic changes, resulting in changes in agricultural systems and management. This transition is likely to provide significant "win-win" opportunities for the conservation of resources, to offset the impacts of climate change. Opportunities to change crop types and introduce more efficient irrigation are among the most promising. Human activity can exacerbate the effect of climate change in this arid/semi-arid region, leading to long-term detrimental effects on ecosystems and human health. The Aral Sea is an illustrative example of the multiplicative effects of resource overuse, which can lead to local environmental and even climate change. Extensive redirection of water from feeder rivers to irrigated agriculture since 1960 has led to a reduction in the surface area of the lake, as well as damage to the surrounding wetlands and the species that depend on them. Air temperature in the vicinity of the lake has increased. Saline and polluted dust from the exposed lake bed has been implicated in significant health problems and increases in infant mortality.
There are some obvious research needs. Clearly, many basic physiological and ecological studies of the effects of changes in atmospheric and climatic conditions are necessary. The most pressing need over much of the region is for sound assessment and monitoring programs to establish current baselines and identify rates of change.
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