In many countries, the dominant water use is for irrigation to support small but economically important permanent pasturelands and croplands. The region is heterogeneous in terms of the countries economies. Two-thirds of the region can be classified as hot or cold desert. In the northern part of the region, a steppe climate prevails, with cold winters and hot summers. A narrow zone contiguous to the Mediterranean Sea is classified as a Mediterranean zone, with wet and moderately warm winters and dry summers.
Permafrost zones exist in high mountain areas in the southeast part of the region.