Greenland melting could accelerate sea-level rise

10/17/11 Matthew Cimitile
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The world's second largest ice sheet is melting. A USF geologist says because of what's happening in Greenland, there are global implications for sea-level rise.

Greenland’s ice sheet covers 80 percent of the island country’s surface and contains roughly eight percent of Earth’s fresh water. And according to University of South Florida geologist Timothy Dixon, recent melting of the ice sheet is beginning to add to global sea-level rise.

“Sea level rise, it is going up about 2 millimeters per year during the last century. At the present time it is probably going up at 3 mm / per year and there is increasing contributions from Greenland and Antarctica.”

Though those numbers may seem small now, experts fear sea-level rise will accelerate as the century continues. At USF's College of Marine Science, Dixon said that Greenland could be one of the biggest contributors to that accelerated rise.

“Greenland, especially Southern Greenland is a little bit different than Antarctica in terms of it’s potential for rapid melting. Basically Southern Greenland fuels the Gulf Stream in the North Atlantic Current. That means it can warm up and melt very quickly on a timescale of perhaps a few decades. I don’t think it will melt in a few decades, but we cannot eliminate the possibility that southern Greenland will undergo some pretty rapid melting in the next few decades.”

Pointing to a graph that showed hundreds of thousands of years of sea-level rise and ice volume information, Dixon said that when ice sheets melted in the past, they did so swiftly.

“When sea-levels fall, it tends to fall relatively slowly, but when sea levels rises, it can rise pretty quickly. So that implies that when the ice sheets grow, they grow slowly, taking sea levels down. But when the ice sheets melt, they can melt pretty rapidly.”

A recent NASA study found that the Greenland ice sheet experienced its greatest melting last summer. In southern Greenland it lasted 50 days longer than average. The science agency estimated faster melting could raise sea levels six inches higher than expected by 2050.

In 2007, the Intergovernmental Panel on Climate Change forecasted that sea level would rise by ½ to 2 feet by the end of the century. But Dixon said those estimates did not include Greenland and Antarctic ice sheet melting from rising temperatures.

“The last IPCC report passed on the whole Greenland part, they said sea level could rise a half a meter plus some unknown amount because of Greenland. That is kind of frightening that we really don’t know what Greenland is going to do.”

Many experts now claim that those numbers are very conservative and sea levels could rise by a meter or more by the end of the century.

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