MELTING GREENLAND July 27, 2012Posted by wmmbb in Global Warming (climate change).
Greenland might better have been called White Land. It history is nothing if not dramatic.
A brief history of Greenland referring to the early settlement, the intrepid exploration to Nova Scotia, records “the Norse population disappears” from 1480 -1500. They had written records.
Now NASA reports:
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 two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.
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. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. 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.
With the following explanation:
Extent of surface melt over Greenland’s ice sheet on July 8 (left) and July 12 (right). 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. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. The satellites are measuring different physical properties at different scales and are passing over Greenland at different times. As a whole, they provide a picture of an extreme melt event about which scientists are very confident. Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory
It seems at this stage, that while this is a dramatic development, it need not be attributed to Global Warming, although presumably it is superimposed on it. I read that CO2 levels around the poles have reached 400 ppm. NASA reports:
“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.”
Despite this caveat, Susan Goldenberg in The Guardian reported that the ice melted at “an unprecedented rate”. The suggestion is among some experts that this event is alarming:
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
Greenland had returned to more typical summer conditions by 21 or
22 July, Mote told the Guardian.
But he said the event, while exceptional, should be viewed alongside
other compelling evidence of climate change, including on the ground
“What we are seeing at the highest elevations may be a sort of sign of
what is going on across the ice sheet,” he said. “At lower elevations
on the ice sheet, we are seeing earlier melting, melting later in the
season, and more frequent melting over the last 30 years and that is
consistent of what you would expect with a warming climate.”
Zwally, who has made almost yearly trips to the Greenland ice sheet for more than three decades, said he had never seen such a rapid melt.
About half of Greenland’s surface ice sheet melts during a typical summer, but Zwally said he and other scientists had been recording an acceleration of that melting process over the last few decades. This year his team had to rebuild their camp, at Swiss Station, when the snow and ice supports melted.
He said he had never seen such a rapid melt over his three decades of
nearly yearly trips to the Greenland ice sheet. He was most surprised
to see indications in the images of melting even around the area of
Summit Station, which is about two miles above sea level.
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. But the rapid melt was viewed as more serious.
“If you look at the 8 July image that might be the maximum extent of warming you would see in the summer,” Zwally noted. “There have been periods when melting might have occurred at higher elevations briefly – maybe for a day or so – but to have it cover the whole of Greenland like this is unknown, certainly in the time of satellite records.”
This presentation suggests that Greenland is on the frontline of Climate Change, with some interesting comments about ice bergs and surprising scenery:
- Miguel Llanos, Greenland again sees widespread melt (NBC News )
- Greenland Ice Sheet Melting is a Cause of Concern (naturenplanet.com)
- Greenland’s ice sheet melt: a sensational picture of a blunt fact (guardian.co.uk)
- Greenland ice sheet melted at unprecedented rate during July (guardian.co.uk)
- Unprecedented Greenland ice sheet surface melt (sciencedaily.com)
- Unprecedented Greenland Ice Sheet Surface Melt (skepticalscience.com)
- NASA warns 97 percent of Greenland ice sheet surface melted in four days (rawstory.com)