tagged w/ Greenland Ice Sheet
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July 24, 2012: 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.
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, Calif., 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 12. Nghiem said, "This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?"
Nghiem consulted with Dorothy Hall at NASA's Goddard Space Flight Center in Greenbelt, Md. Hall studies the surface temperature of Greenland using the Moderate-resolution Imaging Spectroradiometer (MODIS) on NASA's Terra and Aqua satellites. She confirmed that MODIS showed unusually high temperatures and that melt was extensive over the ice sheet surface.
Thomas Mote, a climatologist at the University of Georgia, Athens, Ga; 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 8, about 40 percent of the ice sheet's surface had melted. By July 12, 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 16, it had begun to dissipate.
Even the area around Summit Station in central Greenland, which at 2 miles above sea level is near the highest point of the ice sheet, showed signs of melting. 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 in Hanover, N.H. A National Oceanic and Atmospheric Administration weather station at Summit confirmed air temperatures hovered above or within a degree of freezing for several hours July 11-12.
"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."July 24, 2012: For several days this month, Greenland's surface ice cover melted... more
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Over the last decade or so, scientists have tracked a significant loss of ice from the Greenland Ice Sheet (GIS). While some of that loss has been as a direct result of surface melting, most of it presently appears to be a result of warmer ocean waters melting the ice tongues that stretch out into fjords. Essentially, the warmer water melts the bottom of the glacier and makes it more likely to break up, and as the ice tongue breaks up, the glacier behind the tongue starts to move faster, dumping yet more ice into the ocean.
There has been a significant amount of study of the GIS, and multiple independent lines of evidence have shown that Greenland’s glaciers are thinning and thus losing mass. These include satellite radar altimetry, the GRACE gravity mapping satellites, and both airborne and satellite laser altimetry. Now a peer-reviewed paper published in March shows that another analysis of GRACE and new GPS data has found that mass loss has spread from the warmer southeast coast to the comparably cooler northwest coast, significantly increasing the amount of Greenland coastline affected by mass loss.
More at the link.Over the last decade or so, scientists have tracked a significant loss of ice from the... more
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SHOCKING NEW NASA DATA / NEW PREDICTION = "3 TO 5 YEARS NO ICE IN ARCTIC"
THE PERMAFROST = IS NOW THAWING....
3-5 years All Arctic Ice will be gone. Five years after that... no ice on either pole!
Watch Video as prehistoric methane gas is released under the ice from the thawing permafrost below is ignited.
NEW DATA: The original time to reach the permafrost thawing tipping point wasn't predicted to happen until 2050.
We need to understand what is happening and how the effects of what is now taking place... will change all our lives in the "months and few years ahead".SHOCKING NEW NASA DATA / NEW PREDICTION = "3 TO 5 YEARS NO ICE IN ARCTIC"... more
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Global warming... is much worse that you think.
PLEASE SELECT: "WATCH FULL PROGRAM"
Summary:
Dan Miller's presentation focuses on why the UN IPCC (Intergovernmental Panel on Climate Change) reports are actually best case scenarios. For example, IPCC climate models do not include the effect of melting permafrost releasing greenhouse gases, even though the permafrost is melting now and it holds more greenhouse gases than all that mankind has ever released.
Another example is that IPCC predictions of sea level rise only take into account thermal expansion of the oceans and melting of glaciers; the largest factor, disintegration of glaciers, was not included because it is hard to model. The result is that sea level rise will likely be substantially higher this century than the IPCC predicts.
Miller discusses several other potential catastrophes that are not included in IPCC predictions and also discusses tipping points that could put climate change solutions out of our reach in years or decades, the psychology of climate change, and why it is difficult for people to respond to the threat posed by a warming earth.
His talk concludes with a discussion of ways to address climate change and the risks and opportunities that companies face due to the climate crisis.
More Information:
The Climate Project
http://www.theclimateproject.org/aboutus.php
NASA | Earth Observatory
http://earthobservatory.nasa.gov/IOTD/view.php?id=6632
NASA | Science for a Hungry World: Part 6
http://earthobservatory.nasa.gov/IOTD/view.php?id=6632
HOME PROJECT: A Visual Global Tour /current effects of global warming.
http://www.youtube.com/watch?v=jqxENMKaeCU
.Global warming... is much worse that you think.
PLEASE SELECT: "WATCH FULL... more
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The most detailed satellite information available shows that ice sheets in Greenland and western Antarctica are shrinking faster than scientists thought and in some places are already in runaway melt mode, a new study found.
"Dynamic thinning of Greenland and Antarctic ice-sheet ocean margins is more sensitive, pervasive, enduring and important than previously realized," researchers wrote in the paper published online Wednesday in the peer-reviewed journal Nature.
Using 50 million laser readings from a NASA satellite, scientists for the first time calculated changes in the height of the vulnerable but massive ice sheets and found them especially worse at their edges. That's where warmer water eats away from below. In some parts of Antarctica, ice sheets have been losing 30 feet a year in thickness since 2003, according to the study.
Some of those areas are about a mile thick, so they've still got plenty of ice to burn through. But the drop in thickness is speeding up. In parts of Antarctica, the yearly rate of thinning from 2003 to 2007 is 50 percent higher than it was from 1995 to 2003.
These new measurements confirm what some of the more pessimistic scientists thought: The melting along the crucial edges of the two major ice sheets is accelerating and is in a self-feeding loop. The more the ice melts, the more water surrounds and eats away at the remaining ice.The most detailed satellite information available shows that ice sheets in Greenland... more
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This year, perhaps more than ever before, we are seeing signs that the huge positive feedback of the loss of summer sea ice giving rise to much warmer arctic seas, may be hugely accellerating the melt and catastrophic collapse of the Greenland ice sheet. http://www.msnbc.msn.com/id/32783774/ns/us_news-environment. A Greenpeace research ship is just now seeing the warm surface waters moving toward the coastal fiords and presumably underneath the glaciers, by virtue of their higher salinity and density relative to the meltwaters. As I wrote earlier, density variations under the ice, triggered by incursions of warm seawater could create a powerful "density driven pump" that will draw the warm water under the ice and lead to catastrophic collapse of the entire Greenland ice sheet in short order. This year NOAA's sea surface temperature anomaly maps clearly show an unprecedented blob of cool water streaming out of southern Greenland, where everywhere else around the Greenland coast, the waters are very warm, relative to the recent average temperatures. Ocean water penetration beneath the ice could be the mechanism for very rapid ice sheet collapses and very sudden sea level rises seen at the end of the ice ages.This year, perhaps more than ever before, we are seeing signs that the huge positive... more
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Current data from NOAA satellites sure do look like cold, fresh water from southern Greenland ice melting is spreading clear across the North Atlantic. This is a big deal and the regular news sources aren't picking up on it. The map shown here is the temperature anomaly (current actual sea surface temperature minus long term average temperature) and the blue blob on the map is seen stretching from southern Greenland all the way to Britain. There have been cold water blobs in the past, but never this big in the summertime. You can check out the data directly at http://www.osdpd.noaa.gov/ml/ocean/sst/anomaly.html . You can watch the growth of the anomaly by downloading pictures of the "Full Global" pictures for the year and compare them to past years. Note that the big blue blob seems to be blocking the Gulf Stream big time! Why is this happening right now? Notice all the extra warm water on either side of the cold stream coming from southern Greenland. I think that this salty, warm water is being sucked below the ice in glacial streams along fjords that are below sea level, melting the ice really fast and then exiting to the ocean when the relatively low density melt water rises to the surface at another nearby fjord. I call this a "density driven pump" and I included a schematic of it in the picture attached. Regular color satellite pictures of southern Greenland show light grey water, which is meltwater with finely ground up rock suspended in it, streaming into the sea right next to deep blue water filled fjords, which is the warm salty water inlet to the pump. http://rapidfire.sci.gsfc.nasa.gov/realtime/2009214/ OK, that's a bit complicated, but if it's what is really going down right now, it says that the Greenland ice sheet is dead meat and could totally collapse in a decade or two. And that means about 20 feet of sea level rise! Sell your real estate in Florida right now!Current data from NOAA satellites sure do look like cold, fresh water from southern... more
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By the end of the century sea levels may be rising three times as fast as they are at present, as a result of rapid melting of the Greenland ice sheetBy the end of the century sea levels may be rising three times as fast as they are at... more
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lecoke
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added this
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4 years ago
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