Global warming thaws tropical ice caps

The famous snows of Kilimanjaro are rapidly receding, according to Lonnie Thompson, a professor of geological sciences. At least one-third of the massive ice field atop Tanzania's Mount Kilimanjaro in Africa has melted over the past dozen years. Since the glacier was first mapped in 1912, about 82 percent of it has been lost.

Kilimanjaro joins the list of ice caps atop mountains in Africa and South America that Thompson and others predict to disappear over the next 15 years as a result of global warming.

Peru's Quelccaya ice cap in the Southern Andes Mountains has shrunk by at least 20 percent since 1963. Most disconcerting, Thompson warns, is that the rate of decline for one of the main glaciers flowing out from the ice cap, Qori Kalis, has been 32 times greater in the past three years than it was in the period between 1963 and 1978.

Scientists have long predicted that the first signs of climate change will appear at the fragile high-altitude glaciers within the tropics. The thaw of the Kilimanjaro and Quelccaya ice caps are the most dramatic evidence to date.

"These glaciers are very much like the canaries once used in coal mines," Thompson said. "They're an indicator of massive changes taking place and a response to the changes in climate in the tropics."

As the glaciers recede, so will the amount of water that feeds rivers and valleys below the mountaintops.

"The loss of these frozen reservoirs threaten water resources for hydroelectric power production in the region and for crop irrigation and municipal water supplies," Thompson said. It is likely that many developing countries will replace the power source by burning more fossil fuels.

"What they're really doing now is cashing in on a bank account that was built over thousands of years but isn't being replenished. Once it's gone, it will be difficult to re-form."