Ecosystems: Vegetation models project little change in most arid or desert vegetation types under climate change projections i.e., most lands that are deserts are expected to remain deserts. Greater changes in the composition and distribution of vegetation types of semi-arid areas for example, grasslands, rangelands and woodlands are anticipated. Small increases in precipitation are projected, but these increases are likely to be countered by increased temperature and evaporation. Improved water use efficiency by some plants under elevated CO 2 conditions may lead to some improvement in plant productivity and changes in ecosystem composition. Grasslands, livestock and water resources are likely to be the most vulnerable to climate change in this region because they are located mostly in marginal areas. Appropriate land-use management, including urban planning, could reduce some of the pressures on land degradation. Management options, such as better stock management and more integrated agro-ecosystems, could improve land conditions and counteract pressures arising from climate change. The region is an important refuge for wild relatives of many important crop species; with appropriate conservation measures it may continue to provide a source of genetic material for future climatic conditions.

Hydrology and Water Resources: Water shortage, already a problem in many countries of this arid region, is unlikely to be reduced, and may be exacerbated, by climate change. Changes in cropping practices and improved irrigation practices could significantly improve the efficiency of water use in some countries. Glacial melt is projected to increase under climate change,leading to increased flows in some river systems for a few decades, followed by a reduction in flow as the glaciers disappear.

Food and Fiber Production: Land degradation problems and limited water supplies restrict present agricultural productivity and threaten the food security of some countries. There are few projections of the impacts of climate change on food and fiber production for the region. The adverse impacts that may result in the region are suggested by the results of studies that estimate that wheat production in Kazakstan and Pakistan would decline under selected scenarios of climate change. The studies, however, are too few to draw strong conclusions regarding agricul ture across the entire region. Many of the options available to combat existing problems would contribute to reducing the anticipated impacts of climate change. Food and fiber production, concentrated on more intensively managed land, could lead to greater reliability in food production and reduce the detrimental impacts of extreme climatic events. Countries of the former Soviet Union are undergoing major economic changes, particularly in agricultural systems and management. This transition is likely to provide opportunities to change crop types and introduce more efficient irrigation,providing significant win-win options for conservation of resources to offset the projected impacts of climate change.

Human Health: Heat stress, affecting human comfort levels, and possible spread in vector-borne diseases are likely to result from changes in climate. Decreases in water availability and food production would lead to indirect impacts on human health.

Conclusions: Water is an important limiting factor for eco-systems, food and fiber production, human settlements and human health in this arid region of the world. Climate change is anticipated to alter the hydrological cycle and is unlikely to relieve the limitations placed by water scarcity upon the region. Climate change and human activities may further influence the levels of the Caspian and Aral Seas, which will affect associated ecosystems, agriculture and human health in the surrounding areas. Win-win opportunities exist which offer the potential to reduce current pressures on resources and human welfare in the region and also offer the potential to reduce their vulnerability to adverse impacts from climate change.