Greenland, the largest island in the world, has 85 percent of its area covered by ice. The melting season in Greenland usually lasts from June to early September every year. This year however, the melting of the Greenland ice sheet shattered the seasonal record on August 8, a full four weeks before the season is to come to an end, as per a report of scientists from the City College of New York. The cumulative melting till that date had already shattered the record of 2010, taken over a full season, according to the analysis.
Marco Tedesco, assistant professor of Earth and atmospheric sciences at The City College of New York and the author of a study on the changes the Greenland ice sheet could go through in the 21 century, said "With more yet to come in August, this year's overall melting will fall way above the old records. That's a goliath year - the greatest melt since satellite recording began in 1979."
The record melting has changed the face of southern Greenland with ice sheets thinning at its edges and formation of numerous lakes on top of glaciers. The changes match the prediction of numerous models but are occurring at a pace faster than expected.
Using data from microwave satellite sensors, the scientist measured the duration and extent of melting throughout the season across the whole ice sheet. This "cumulative melting index" is the measure of the intensity of the melting season. A higher score on the index indicates more melting has occurred. Calculations revealed that the cumulative melt in 2012 exceeded the melting that occurred in 2010.
The August 8 record is different from the record melting reported by NASA in mid-July. During that time, 97 percent of the surface of the ice sheet had melted, but the liquid water refroze after a few days changing the physical characteristics of the snow pack without adding to the run off of melt water that contributes to rise in sea levels.
The "cumulative melting index" however, also accounts for melt water flowing into the ocean, as this phenomenon can speed up the sliding of the ice sheet into the sea.
Greenland reportedly experienced record melting this year in almost every region - the west, northwest and northeast of the continent, including those areas at high elevations. Usually ice and snow at high altitudes melt for a few days at most. This year it has already gone on for two months.
Professor Tedesco however cautions, "We have to be careful because we are only talking about a couple of years and the history of Greenland happened over millennia." He added, "But as far as we know now, the warming that we see in the Arctic is responsible for triggering processes that enhance melting and for the feedback mechanisms that keep it going. Looking over the past few years, the exception has become part of the norm."
by RTT Staff Writer
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