Per the NASA press release: Measurements from three satellites showed that on July 8, 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 12.
On average in the summer, about half of the surface of Greenland’s ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. This year’s dramatic ice melt is more than double the normal rate of the summer season.
This isn’t just another story about ice melting in a far away land. The satellite images were so shocking that scientists couldn’t believe what they were seeing. Son Nghiem of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said, “This was so extraordinary that at first I questioned the result: Was this real or was it due to a data error?” But it wasn’t an error. The data was further confirmed by three different NASA labs and has increased the already growing attention that this region has been receiving. Just last week Greenland’s Peterman Glacier calved an ice island twice the size of Manhattan.
Although one large ice melt can be a natural occurrence, such pronounced melting at Summit and across the ice sheet has not occurred since 1889.
“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,” says 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.”