Greenland ice, it seems, can vanish in a flash, with new satellite images showing that over just a few days this month nearly all of the veneer of surface ice atop the island's massive ice sheet had thawed. "This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?" said Son Nghiem of NASA's Jet Propulsion Laboratory in Pasadena, Calif., referring to the July 12 images taken by the Indian Space Research Organisation's (ISRO) Oceansat-2 satellite. As for what caused the disappearing ice, University of Georgia, Athens climatologist Thomas Mote suggests it could be a ridge or dome of warm air hovering over Greenland that coincided with the extreme melt. Extent of surface melt over Greenland’s ice sheet on July 8 (left) and July 12 (right) based on data from three satellites. The images, snapped by three satellites, showed that about 40 percent of the ice sheet had thawed at or near the surface on July 8; just days later, on July 12, images showed a dramatic increase in melting with thawing across 97 percent of the ice sheet surface. Scientists attributed the sudden melt to a heat dome, or a burst of 
 
 unusually warm air, which hovered over Greenland from 8 July until 16 
 
 July. The melting of such a huge ice sheet — spanning an area of 656,000 square miles (1.7 million square kilometers) — is important for various reasons, particularly its potential effect on sea levels. It was the second unusual event in Greenland in a matter of days, after an iceberg the size of Manhattan broke off from the Petermann glacier. "Ice cores from Summit show that melting events of this type occur about once every 150 years on average," said study researcher Lora Koenig, a glaciologist at NASA's Goddard Space Flight Center in Greenbelt, Md. In this instance of this month's extreme melting, Mote said there was evidence of a heat dome over Greenland: or an unusually strong ridge of warm air. The latest in a series of these heat domes, which have dominated Greenland weather since May, began to move over Greenland on July 8, before coming to a halt over the ice sheet some three days later.
– Greenland isn't just losing Manhattan-sized chunks of ice from its huge glaciers. A heat-dome that moved over Greenland on July 8 caused surface melt to soar from 40% to an unprecedented 97% in just four days, reports Live Science. Typically, just half of Greenland's surface ice melts during the summer. "This was so extraordinary that at first I questioned the result: Was this real or was it due to a data error?" said one researcher. There were even signs of ice melt at Summit Station in central Greenland, a point two miles high and near the thickest part of the ice sheet. "Ice cores from Summit show that melting events of this type occur about once every 150 years on average," said one glaciologist. "With the last one happening in 1889, this event is right on time." However, she cautioned that such a wide-ranging melt was rare and a potential warning. "If we continue to observe melting events like this in upcoming years, it will be worrisome," she told the Guardian.