NASA
When scientists saw melting across a whopping 97 percent of Greenland’s icy surface last summer, they were quick to note that such an event is rare, but not unprecedented.
The last time it happened was in 1889, so while man-made global warming is clearly involved it isn’t necessarily the entire story.
A new report in Nature on Wednesday has now helped flesh out the explanation: data from Summit Station, at the frozen island’s highest point, 10,551 feet above sea level, show that unusually warm temperatures in the region were enhanced by a blanket of low-level clouds that trapped extra heat from the Sun.
But while the events that led to the melt may have been unusual, said lead author Ralf Bennartz, an atmospheric scientist at the University of Wisconsin, in an interview, “I tend to believe we will see more of them toward the end of century.”
If so, the consequences could be dire: combined with faster-flowing glaciers dumping more ice into the sea, episodes of surface melting could accelerate the disintegration of Greenland’s 680,000 cubic miles of ice.
If all of that ice entered the ocean, it would raise sea level by some 20 feet, inundating the world’s coastal regions, displacing hundreds of millions of people and destroying trillions of dollars worth of property.
Even with enhanced melting, that’s unlikely to happen for several hundred years — but climate scientists already expect ice and meltwater to drive sea level up by some 3 feet by 2100, enough todo enormous damage.
Indeed, sea ice has been on a downward spiral ever since satellites first started to make observations in the 1970s, to the point where commercial shipping across the Arctic Ocean could soon be a real possibility.
http://www.weather.com/news/clouds-enhanced-greenland-ice-melting-20130404
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