More summer sun accelerating Greenland ice melt, study says

Scientists at the University of Bristol in the United Kingdomsuggest increasing sunshine over the past 20 years is acceleratingice melt across Greenland.

The findings in their new study are concerning, as Greenland's ice sheetis1.7 million square kilometres. If all of the ice sheet melted, its estimated that global sea levels could rise by six metres.

The researchers found that even just a one per cent decrease in cloud cover is equal to 27 gigatons of extra ice melt on the Greenland ice sheet. That's180 million times the weight of a blue whale.

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"Greenland has become the biggest single contributor to global sea level rise, and it has been shown that 25 per cent of global sea level rise can be attributed to Greenland ice sheet melt alone," StefanHofer, lead author of the study published in Science Advances, told CBC News in an email

"And global sea level rise affects and will affect millions of people living close to the shores. So it is a matter of global importance."

The researchers found that, since 1995, Greenland has lost about 4,000 gigatons of ice.

Climate drivers

Satellite observations found there has been a marked decrease in thick summercloud cover from 1982 to 2009, with some suggesting a reduction of up to 84 per cent over June to August.

Some of the largest reductions occurred in western and southern Greenland. But in the northeast, cloud cover actually increased.

However, the decrease is notable: much of southern Greenland saw a reduction of up to 10 per cent, which the study says is in direct correlation to atmospheric circulation changes seen since the 1990s.

The Arctic iswarming faster than anywhere else on our planet. The researchers believe the warming allows more heat to escape from open waters, whichwarms the atmosphere above. Thischanges the atmospheric circulation patterns, bringing more clear skies to parts of Greenland.

This increase in summersunlight, Hofer believes, explains about two-thirds of Greenland's ice melt since the 1990s.Greenland's ice sheet has been shrinking since the turn of the century, with ice loss nearly doubling since 2003.

Jonathan Bamber, co-author of the paper, said such large changes have not been seen since 1850, when records were first kept.