Glacier melting could be reversible

The melting of Greenland’s glaciers may be more sensitive to climate change than previously assumed, according to new research which found they can also quickly expand during relatively short periods of climatic cooling.

The Jakobshavn Isbrae peak on Greenland’s ice sheet grew rapidly during two different centuries of cooling thousands of years ago, according to the scientists from the University at Buffalo.

Jason Briner, a professor of geology at the university and lead researcher of the Greenland team, said, “When we look at the geologic record, we are finding out that the large rivers of ice that drain ice sheets are extremely sensitive to climate change, both warming and cooling. Probably the larger these rivers of ice are, the more sensitive they are to climate change.”

Briner has been taking teams to the Arctic region for several years, hoping to uncover the history of the remote landscape. On their latest trip, they dated sediment from Jakobshavn Isbrae and its surrounding lake and found a single layer of rock, thought to be around 9,200 years old, set between two layers of plant matter. This discovery implies that the cycle of melting went into retreat for a period.

The scientists identified another stage of advancement around 8,200 years ago by dating boulders in a trail of debris left where the glacier once stood. Although the researchers cannot say how much the ice cap grew by during these times, they claim the fact that it advanced at all during short cooling periods during warming times demonstrates a high sensitivity to climate change.

(Photos: Anders Peter Amsnæs)