and MELTING FAST
http://ngm.nationalgeographic.com/2010/06/melt-zone/greenland-animation
http://news.nationalgeographic.com/news/2008/06/080619-greenland-ice.html
http://earthobservatory.nasa.gov/IOTD/view.php?id=78607

Nearly the entire ice sheet covering Greenland—from its thin coastal edges to its two-mile-thick center—experienced some degree of melting for several days in July 2012. According to measurements from three satellites and an analysis by NASA and university scientists, an estimated 97 percent of the top layer of the ice sheet had thawed at some point in mid-July, the largest extent of surface melting observed in three decades of satellite observations. The data visualization above shows the extent of surface melting in Greenland on July 8 (left) and July 12, 2012 (right). The maps are based on observations from the Special Sensor Microwave Imager/Sounder (SSMI/S) on the U.S. Air Force’s DMSP satellite, from India’s OceanSat-2, and from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites. The satellites measure different physical properties at different scales, and they pass over Greenland at different times. Taken together, they provide a picture of an extreme melt event.

On July 8, satellites showed that about 40 percent of the ice sheet had undergone thawing at or near the surface. By July 12, the extent of melting spread dramatically beyond the norm. In the images above, areas classified as “probable melt” (light pink) correspond to sites where at least one satellite detected surface melting. Areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected melting. Every summer, a fraction of the surface of the Greenland ice sheet naturally melts. At high elevations, most melt water quickly refreezes in place. Near the coast, some of the melt is retained by the ice sheet and the rest is lost to the ocean. In mid-July 2012, Son Nghiem of NASA’s Jet Propulsion Laboratory was analyzing radar data from the Indian Space Research Organisation’s Oceansat-2 satellite when he noticed that most of Greenland appeared to have undergone surface melting on July 12. “This was so extraordinary that at first I questioned the result,” said Nghiem. “Was this real or was it due to a data error?” Nghiem consulted with Dorothy Hall, who studies the surface temperature of Greenland from NASA’s Goddard Space Flight Center. She confirmed that MODIS showed unusually high temperatures over the ice sheet surface and that melt was extensive. Colleagues Thomas Mote of the University of Georgia and Marco Tedesco of the City University of New York also confirmed the melt with passive-microwave data from the DMSP.

The extreme melting coincided with an unusually strong ridge of warm air—a “heat dome”—over Greenland. The ridge was one in a series that dominated Greenland’s weather between May and July 2012. Even the area around Summit Station in central Greenland, which at two miles above sea level is near the highest point of the ice sheet, showed signs of melting. A National Oceanic and Atmospheric Administration weather station at Summit confirmed that air temperatures hovered above or within a degree of freezing for several hours from July 11 to July 12. Such pronounced melting at Summit and across the ice sheet has not occurred since 1889, according to ice cores analyzed by Kaitlin Keegan at Dartmouth College. “Ice cores from Summit show that melting events of this type occur about once every 150 years,” said Lora Koenig, a NASA scientist and member of the team analyzing the satellite data. “With the last one happening in 1889, this event is right on time. But if we continue to observe melting events like this in upcoming years, it will be worrisome.” “The Greenland ice sheet is a vast area with a varied history of change,” said Tom Wagner, NASA’s cryosphere program manager. “This event, combined with other natural but uncommon phenomena such as the large calving event earlier this week on Petermann Glacier, are part of a complex story.”

The 100-year smoothed accumulation record from the GISP2 core for the period A.D. 500 to the present. The arrows show locations of visually identified melt layers in the ice core. [1994]

PRECEDENTED
http://www.wired.com/geekmom/2012/07/greenland-ice-sheet-melting/
by Patricia Vollmer / July 26, 2012

From 8 July to 12 July, Greenland’s surface transitioned from approximately 40% melted water to approximately 97%. That’s a lot of melting in not a lot of time. The first indications were seen while analyzing radar reflectivity data from the Indian Space Research Organisation’s (ISRO) Oceansat-2 satellite, then it was verified with temperature data from the American Moderate-resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites. Scientists at NASA Goddard Space Flight Center verified that the MODIS data indicated unusually high temperatures during the second week of July over the landmass; these conditions coincided with an upper air high pressure system, the same large-scale phenomena that has caused the recent heat waves in the eastern United States.

A third satellite verification was brought in, thanks to analyses from the Special Sensor Microwave Imager (SSM/I) on the U.S. Air Force’s Defense Meteorological Satellite Program (DMSP) satellites.Several of the channels on the SSM/I imager are tuned to sense data through the atmosphere all the way to the surface of the earth, detecting whether the surface is dry, flooded, forested, ocean water, iced-over or thawed.

Finally, on-site weather observations at research stations throughout Greenland have verified the warmer temperatures that correlate with the surface ice melting. While this news is very significant in the climatology and glaciology community, some are going step further and are attempting to connect it with other indicators of climate change. The definitive answer to that question is not clear and many news outlets are doing a good job providing a balanced view of this news. Several points should be made about this news:

• The media is using the term “unprecedented”. In fact, the NASA press release about this is using the term “unprecedented”. What is “unprecedented” about this news is the ability for the satellites to see the warming, and the speed with which that data can be seen by the scientists. The warming itself certainly is not unprecedented. Conditions supporting this were last measured directly in 1889, and ice core samples, which have the ability offer evidence of climate conditions over 100,000 years old, have indicated that vast warming occurs approximately every 150 years. For this to happen in 2012 is not unreasonable.
• The satellites taking the measurements require some understanding regarding their capabilities and limitations. Greenland is unique in that there is very little else besides rock, ice, snow and water for measurement. So I’m more confident in Greenland’s data than I would be in many other locations. Sand, loam, clay, forests and urban areas can often make detection more difficult. The two satellites mentioned above that measure reflectivities of the land mass surface (Oceansat-2 and SSM/I) are only measuring a few centimeters deep. It essentially measures data that translates into water on the surface. So even if there’s a slight sheen of water for the satellites to sense, there could still be miles of ice directly underneath.  As soon as the temperatures dip below freezing again, it will freeze again.
• Melting happens on Greenland every year at this time. The melting itself is not what’s unusual. It’s theamount of melting.  Temperatures have been measured as high as 42F this July at locations that rarely exceed freezing temperatures year-round, according to NASA scientist Tom Wagner. Some media outlets are coming up with some pretty crazy headlines that might make readers believe Greenland has never experienced melting before.
• Because we have more data than ever before to assess this current melting period, it’s difficult to compare it to the very limited data — point data, if you will — of all the previous melting events. Ice cores and temperature measurements are many kilometers apart.

Meltwater from the surface of the ice sheet plunges into the darkness of a moulin

MEASURABLE
http://www.globalwarming.org/2012/07/26/the-greenland-ice-melt-should-we-be-alarmed/
by Marlo Lewis / July 26, 2012

How much ice is Greenland shedding, and what are the implications for global sea-level rise? A study published in Science magazine in 2006 by Scott Luthcke of NASA and colleagues used satellite gravity measurements to estimate annual net ice loss in Greenland from 2003 to 2005. The researchers estimated that the ice sheet gained 55 gigatons per year from snowfall at higher elevations and lost 155 gigatons per year at lower elevations, yielding a net annual ice loss of 101 gigatons. That translates into an annual loss of 27 cubic miles of ice per year, or 2,700 cubic miles per century. Sounds huge — until you compare it to Greenland’s total ice mass. The Greenland Ice Sheet holds 706,000 cubic miles of ice. So at the 2003-2005 ice loss rate, Greenland will lose less than 4/10th of 1% of its ice mass in the 21st century. Apocalypse not.

Pat Michaels reviews a more recent gravity measurement study (Wu. et al. 2010, published inNatureGeoscience) that estimates ice mass balances in both Greenland and Antarctica from 2002 to 2008. Similar to the Luthcke study, the Wu team finds that Greenland’s net ice loss is 104 gigatons per year. They also estimate that Antarctica is losing 87 gigatons per year.

SUMMIT STATION
http://dartmouthigert.wordpress.com/2012/07/21/new-summit-melt-layer/
New Summit Melt Layer
by Kaitlin Keegan / July 21, 2012

“I arrived at Summit Station on July 13th, while traveling with the Joint Science and Education Program (JSEP) for a short visit to the camp. When we arrived, Summit Station had been experiencing above freezing temperatures for multiple days prior to our arrival and a melt layer formed on the near surface snow. I have been studying the physical properties of the top layers of the ice, the firn, at Summit and NEEM for my Ph.D. research. Recently, I have been focused on the melt layers present in both firn cores because they occur very infrequently. At Summit, there is only one other melt layer besides the melt layer from this past week and this previous melt layer dates to 1889. The most interesting part of being at Summit Station just after a melt event had occurred, is that the melt layer formation process could be observed. When studying a firn core, there is only a small cross section of the firn column that can be examined, which makes it hard to understand how the melt layer formed and how evenly distributed it is. Studying snow pits at Summit, including the recent melt layer, presents a unique opportunity for us to understand how previous melt events occurred. While at Summit density, stratigraphy, and permeability measurements have been taken and samples will also be brought back to the laboratory at Dartmouth, which will give us a clue about melt layers in the past.”

MELTWATER
http://www.guardian.co.uk/environment/2012/jul/25/greenland-glacier-bridge-destroyed-video?intcmp=239
Scientists in Kangerlussuaq on western edge of ice sheet film runoff from glacier washing out roads and taking out a tractor
by Suzanne Goldenberg / 25 July 2012

The gust of warm air that caused the unprecedented thaw inGreenland‘s surface ice also appears to have caused unusually high runoff from a glacier, wiping out a crossing near a key research and transport hub. Scientists who fly in Kangerlussuaq, near the western edge of the ice sheet, have been keeping an eye on the Watson river bridge for years. The bridge dates from the 1950s, but wasn’t built for the magnitude of spring and summer melt of the last 12 years or so, said Jason Box, a glaciologist at Ohio State University who returned on Tuesday from a three-week stint in Greenland. “The midsummer floods have been growing and threatening this bridge and finally took it out,” he said. “It washed out roads and took out a tractor.”

The river is fed by the nearby Russell Glacier, which sits just outside of town. Unlike other glaciers, which are exposed to the warming ocean waters, it sits entirely on land. Box, who works extensively in Greenland, has publicly warned that the ice melt is accelerating, in part because the snow and ice are losing their reflective capabilities. It was T-shirt weather some days in Greenland this month, he said. Such warms days were not unheard of though, he added.