Greenland Ice Sheet is Melting More Rapidly Than Previously Believed

Dec 16, 2014 07:11 AM EST | Matt Mercuro

Greenland ice loss predictions and its impact on rising sea levels may have been underestimated, according to a new study by scientists at the University of Leeds.

The discovery follows a study published this week in Nature Climate Change which discusses the future distribution of lakes that form on the ice sheet surface from melted snow and ice, called supraglacial lakes.

Before the finding, the impact of supraglacial lakes on Greenland ice loss had been assumed to be minor, but new research has shown that they will migrate father inland over the next half century, possibly changing the ice sheet flow in various ways.

"Supraglacial lakes can increase the speed at which the ice sheet melts and flows, and our research shows that by 2060 the area of Greenland covered by them will double," said Dr. Amber Leeson from the School of Earth and Environment and a member of the Centre for Polar Observation and Modelling (CPOM) team, who led the study, according to a press release.

Supraglacial lakes are darker than ice, meaning they absorb more of the Sun's heat. This leads to increased melting, according to Leeson. Once the lakes reach a dangerous size, they drain through ice fractures, which lets water reach the ice sheet base causing it to slide more quickly into the oceans.

These changes can also cause further melting.

"When you pour pancake batter into a pan, if it rushes quickly to the edges of the pan, you end up with a thin pancake. It's similar to what happens with ice sheets: the faster it flows, the thinner it will be," said Leeson.

"When the ice sheet is thinner, it is at a slightly lower elevation and at the mercy of warmer air temperatures than it would have been if it were thicker, increasing the size of the melt zone around the edge of the ice sheet."

Supraglacial lakes have formed at low elevations around the coastline of Greenland until now. At higher elevations, today's climate is too cold for lakes to form.

The researchers used observations of the ice sheet from the Environmental Remote Sensing satellites operated by the European Space Agency and estimates of future ice melting taken from a climate model in order to drive simulations of how meltwater will flow and pool on the ice surface to form lakes, according to the release.

Since the 1970s, the band in which supraglacial lakes can form on Greenland has crept further inland. From the results of the new study,

Thanks to the new study, researchers now predict that, as Arctic temperatures rise, supraglacial lakes will spread much farther inland, doubling the area of Greenland that they cover today by 2060.

"The location of these new lakes is important; they will be far enough inland so that water leaking from them will not drain into the oceans as effectively as it does from today's lakes that are near to the coastline and connected to a network of drainage channels," said Leeson.

"In contrast, water draining from lakes farther inland could lubricate the ice more effectively, causing it to speed up."

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