"There are dozens, if not hundreds, of photos of mid-latitude glaciers you could show where there is absolutely no question that they are declining in response to the warming atmosphere," said climatologist Philip Mote, a University of Washington research scientist.

But on Africa's Kilimanjaro, he said, processes are far different from those that have diminished glacial ice in temperate regions closer to the poles.

Mote and Georg Kaser, a University of Innsbruck glaciologist, attribute the ice decline to decreased snowfall and the vertical shape of the ice's edge, which allows it to shrink but not expand.

Unlike mid-latitude glaciers that are warmed and melted by summer air, ice loss on Kilimanjaro is driven strictly by solar radiation, the scientists said. Ice loss is mainly through a process called sublimation that occurs at below-freezing temperatures and converts ice directly to water vapor without going through the liquid phase. Mote likens it to moisture-sapping conditions that cause freezer burn.

The study appears in the July-August issue of American Scientist magazine.