Most of the 12 desert regions whose future climate was studied face a drier future, the report said. Experts predicted that rainfall would fall by as much as 20 percent by the end of the century due to human-induced climate change.
Compounding the threat is the melting of glaciers. A large fraction of water used for agricultural and domestic purposes in deserts in the southwestern United States, Central Asia and South America come from rivers that originate in glaciers and snow-covered mountains, the report said.
The glaciers on the Tibetan plateau, for example, may decline by as much as 80 percent by the end of the century, according to the Intergovernmental Panel on Climate Change, a group of scientists advising the United Nations.
<snip>
The report warned that renewable water supplies fed to deserts by large rivers are also in danger because of climate change and booming growth. It cited the Rio Grande and Colorado rivers in North America, the Tigris and Euphrates in southwestern Asia and the Amu Darya and Indus rivers in Central Asia as being under threat.
http://news.yahoo.com/s/ap/20060605/ap_on_sc/global_warming_deserts