NASA Scientists’ Satellite Data analysis reveals Large Ice Sheet Melt off in Greenland

July 25, 2012 |

Written by Alan Buis
NASA’s Jet Propulsion Laboratory

Pasadena, CA – For several days this month, Greenland’s surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations.

Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its 2-mile-thick (3.2-kilometer) center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

Extent of surface melt over Greenland’s ice sheet on July 8th (left) and July 12th (right). Measurements from three satellites showed that on July 8th, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12th.

But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.

Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.

“The Greenland ice sheet is a vast area with a varied history of change. This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story,” said Tom Wagner, NASA’s cryosphere program manager in Washington. “Satellite observations are helping us understand how events like these may relate to one another as well as to the broader climate system.”

Son Nghiem of NASA’s Jet Propulsion Laboratory in Pasadena, CA was analyzing radar data from the Indian Space Research Organisation’s (ISRO) Oceansat-2 satellite last week when he noticed that most of Greenland appeared to have undergone surface melting on July 12th. Nghiem said, “This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?”

Thomas Mote, a climatologist at the University of Georgia, Athens; and Marco Tedesco of City University of New York also confirmed the melt seen by Oceansat-2 and MODIS with passive-microwave satellite data from the Special Sensor Microwave Imager/Sounder on a U.S. Air Force meteorological satellite.

The melting spread quickly. Melt maps derived from the three satellites showed that on July 8th, about 40 percent of the ice sheet’s surface had melted. By July 12th, 97 percent had melted.

This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland’s weather since the end of May. “Each successive ridge has been stronger than the previous one,” said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16th, it had begun to dissipate.

“Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time,” said Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. “But if we continue to observe melting events like this in upcoming years, it will be worrisome.”

Nghiem’s finding while analyzing Oceansat-2 data was the kind of benefit that NASA and ISRO had hoped to stimulate when they signed an agreement in March 2012 to cooperate on Oceansat-2 by sharing data.

For more information about NASA programs, visit: www.nasa.gov .

The California Institute of Technology in Pasadena manages JPL for NASA.

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One Response to “NASA Scientists’ Satellite Data analysis reveals Large Ice Sheet Melt off in Greenland”

1. mikewarner Says:
   July 25th, 2012 at 6:55 am

   Ever why it is called “Greenland”. Long before SUV’s existed, during the dark ages, Greenland was GREEN during another warming period. There have been many warming periods in earths history, many cooling periods too. We have been coming out of a cooling period known as “the little ice age” which is why we have been warming. Global warming is POLITICAL. It has an agenda of it’s own and is NOT science. True science is NEVER SETTLED. It is only accepted until the next theorist discovers it’s faults and comes to a new conclusion.

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