Glacier Fluctuations Influenced by Temperature Rather than Weather, Study Finds

At the height of the last Ice Age, the expansion and contraction of glaciers in Africa's Rwenzori Mountains were driven by air temperature, rather than precipitation, according to new research that carries with it a host of implications affecting glaciers today.

The study, led by Dartmouth College researchers and financed by National Geographic Society and the National Science Foundation, supports the idea that many of today's tropical glaciers are shrinking largely because of a warming climate, rather than a decrease in snowfall or other factors.

Another recent study also found that air temperature is also likely influencing the fluctuating size of the Quelccaya Ice Cap in South America over the past millennium.

The most recent study, published in the journal Geology, details scientists' work charting the advance and retreat of African glaciers using the beryllium-10 surface exposure dating method.

By using beryllium-10 dating, scientists can determine the age of boulders atop sediment ridges known as moraines, which mark the past position of glaciers.

"The results indicate that glaciers in equatorial East Africa advanced between 24,000 and 20,000 years ago at the coldest time of the world's last ice age," Dartmouth College said in a statement. "A comparison of the moraine ages with nearby climate records indicates that Rwenzori glaciers expanded contemporaneously with regionally dry, cold conditions and retreated when air temperature increased.

"The results suggest that, on millennial time scales, past fluctuations of Rwenzori glaciers were strongly influenced by air temperature."