For years scientists have known that more carbon dioxide -- a prime suspect in global warming -- is being released into the atmosphere than is accounted for by rising levels of atmospheric carbon and by known carbon "sinks" such as the oceans and forests. Suspecting that the world's vast rangelands may be the unidentified carbon sink that is significantly tempering global warming, an international team led by UC Davis researchers is turning its attention to the central Asian rangelands. "Properly managed rangelands could have a relevance for global climate stability comparable to conserving the tropical rain forests," says Montague Demment, director of the UC Davis-based Small Ruminant/Global Livestock Collaborative Research Support Program, which is coordinating the study. "We may very well find that conservation and restoration of the rangelands, in the United States and internationally, have a significant impact on the world's 'carbon budget' and are critical factors in slowing global warming." Restoring central Asia's rangelands, which occupy more than 647 million acres, could be equivalent to a 30 percent reduction in the carbon emissions caused by humans in all of the former Soviet Union, Demment says. Conversely, rangeland degradation through cultivation, grazing or development could release substantial amounts of carbon dioxide into the atmosphere. The rangeland project, led by Emilio Laca, an assistant professor of agronomy and range science at UC Davis, and funded by the U.S. Agency for International Development, will construct a natural resource database for use in quantifying the impact of central Asian rangelands on the global carbon budget.