Sun's Past Strength Took Toll On Tropical Glaciers, Worsens Today's Outlook

A study conducted in part by the University of Alberta in Edmonton, along with the universities of Massachusetts, Pittsburgh, Barcelona and Caracas, shows that even modest natural variations of solar radiation in the Venezuelan Andes during the last 1,500 years affected the region's highly sensitive glaciers.

The study is published in the latest issue of the Proceedings of the National Academy of Sciences. The scientists studied lake sediments to reconstruct the climatic and glacial history of the Cordillera deMérida, the northernmost mountain range in the Andes, and headwater of the Orinoco drainage.

Given that the energy surplus associated with industrial greenhouse gases is far greater than the subtle phasing of solar output of the last millennium, future climate change poses a very real threat to the fragile tropics, especially with respect to water resources, said Dr. Alexander Wolfe, an associate professor of Earth and Atmospheric Sciences at the University of Alberta.

"What this implies is that, regardless of what the sun does naturally, warmer futures for the tropics are virtually assured," Dr. Wolfe said. High-altitude glaciers are already melting rapidly across the tropics, which is especially grave for regions that depend on glacier melt for domestic, industrial, and agricultural water supplies.