Threats to water supplies in the tropical Andes

Climate models predict that greenhouse warming will cause temperatures to rise faster at higher than at lower altitudes. In the tropical Andes, glaciers may soon disappear, with potentially grave consequences for water supplies. According to general circulation models of future climate in a world with double the pre-industrial carbon dioxide (CO2) concentrations, the rate of warming in the lower troposphere will increase with altitude. Thus, temperatures will rise more in the high mountains than at lower elevations. This articles looks at the effects of climate change to water supplies that are predicted to occur in the high mountains of Ecuador, Peru, Bolivia, and northern Chile. If the models are correct, the changes will have important consequences for mountain glaciers and for communities that rely on glacier-fed water supplies. American Association for the Advancement of Science (AAAS) www.sciencemag.org SCIENCE VOL 312, 23 JUNE 2006