Greenland experiences melting over 97% of its area in mid-July
Son Nghiem of NASA's Jet Propulsion Laboratory in Pasadena, CA, was analyzing radar data from the Indian Space Research Organization's Oceansat-2 satellite last week when he noticed that 97% of Greenland appeared to have undergone surface melting on July 12--an event completely unprecedented in 30 years of satellite measurements. In a July 24 press release from NASA, Nghiem said, "This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?" Multiple satellite data sets confirmed the remarkable event, though. Melt maps derived from three different satellites showed that on July 8, about 40 percent of the ice sheet's surface had melted, as a strong ridge of high pressure set up over Greenland. By July 12, the melting had expanded to cover 97% of Greenland. As I blogged about last week, temperatures at at the top of the Greenland Ice Sheet, 10,551 feet (3216 meters) above sea level, and 415 miles (670 km) north of the Arctic Circle, had risen above the freezing mark four times in the 12-year span 2000 - 2011. But in mid-July 2012, temperatures eclipsed the freezing mark on five days, including four days in a row from July 11 - 14. Interestingly, ice core records show that in 1889, a similar pronounced melt event occurred at the top of the Greenland Ice Sheet, and such events occur naturally about every 150 years. "But if we continue to observe melting events like this in upcoming years, it will be worrisome," said Lora Koenig, a NASA/Goddard glaciologist and a member of the research team analyzing the satellite data. Such an event could occur as early as this weekend: the latest wunderground forecast for the Greenland Summit calls for above-freezing temperatures to return again by Saturday through Tuesday, with a high of 36°F (2°C) on Tuesday. This would come close to the record warm temperature at Summit of 3.6°C set just two weeks ago. Exceptionally warm temperatures in Greenland this July have been made more likely by the fact that Arctic sea ice area has been at record low levels so far this month. Furthermore, the Greenland Ice Sheet has become darker this July than at any point since satellite measurements began (Figure 2), allowing Greenland to absorb more solar energy and heat up.
Figure 1. 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. Image credit: NASA.
Figure 2. The albedo (reflectivity) of the Greenland Ice Sheet at its highest elevations (2,500 - 3,200 meters, or 8,200 - 10,500 feet) has steadily decreased in recent years as the ice has darkened due to increased melting and dark soot being deposited on the ice from air pollution. This July, the high elevations of Greenland were the darkest on record, which helped contribute to the record warm temperatures observed at the Greenland Summit. Image credit: Dr. Jason Box, Ohio State University.
Video 1. Melt water from the record July temperatures in Greenland fed the raging Watson River, which smashed two bridges connecting the north and south of Kangerlussuaq (Sønder Strømfjord), a small settlement in southwestern Greenland. The flow rate of 3.5 million liters/sec was almost double the previous record flow rate.
Greenland's Petermann Glacier
Greenland's glaciers have seen significant changes in recent years, as they respond to warmer air and water temperatures. Northwest Greenland's Petermann Glacier has seen two massive calving events in the past two years, though it is uncertain if these events were caused by the warming climate. The most recent event came on July 16, 2012, when the glacier calved a 46 square-mile iceberg two times the size of Manhattan. The same glacier calved an iceberg twice as big back on August 4, 2010--the largest iceberg observed in the Arctic since 1962. The freshwater stored in that ice island could have kept the Delaware or Hudson rivers flowing for more than two years, or kept all U.S. public tap water flowing for 120 days. According to a university press release by Andreas Muenchow, associate professor of physical ocean science and engineering at the University of Delaware's College of Earth, Ocean, and Environment, “While the size is not as spectacular as it was in 2010, the fact that it follows so closely to the 2010 event brings the glacier’s terminus to a location where it has not been for at least 150 years. Northwest Greenland and northeast Canada are warming more than five times faster than the rest of the world, but the observed warming is not proof that the diminishing ice shelf is caused by this, because air temperatures have little effect on this glacier; ocean temperatures do, and our ocean temperature time series are only five to eight years long — too short to establish a robust warming signal.”
Figure 3. The massive 46 square-mile iceberg two times the size of Manhattan that calved from Greenland's Petermann Glacier on July 16, 2012, as seen on July 21, 2012, using MODIS satellite imagery. Image credit: NASA.
Related posts
Record warmth at the top of the Greenland Ice Sheet (July 18, 2012)
Unprecedented May heat in Greenland; update on 2011 Greenland ice melt
Greenland update for 2010: record melting and a massive calving event
Jeff Masters
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MIC017-111-145-260530-
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BAY COUNTY IN SOUTHEAST MICHIGAN...
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* UNTIL 130 AM EDT
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MPH. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING FROM
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PENNY SIZE HAIL MAY ALSO ACCOMPANY THESE DAMAGING WINDS.
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PORTER TOWNSHIP AND GORDONVILLE AROUND 1215 AM EDT.
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WILLARD AND POSEYVILLE AROUND 1225 AM EDT.
THE WARNING INCLUDES AREAS SURROUNDING THESE LOCATIONS...
ZILWAUKEE... ST. CHARLES... SANFORD...
SAGINAW... PLEASANT VALLEY... PINCONNING...
OIL CITY... OAKLEY... MUNGER...
MIDLAND... MERRILL... MARION SPRINGS...
LINWOOD... KAWKAWLIN... FREELAND...
FRANKENMUTH... ESSEXVILLE... EDENVILLE...
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FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF
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4346 8438 4347 8461
TIME...MOT...LOC 0355Z 280DEG 34KT 4378 8442 4339 8489
WIND...HAIL 60MPH 0.75IN
My post from yesterday morning (Jul 25 8 AMish) was a pain to get up. You can read the fully corrected version now...if anyone cares...
Working on the next post now...
stuff west of the windy city is what you have to watch
stuff over cen mich will traverse eastward overnight across south cen ont and slowly drift s se as warm front crosses the region
sorry but you are incorrect
its
global warming/climate change/climate shift
Not much happened before
Well, you're entirely right. (Some people don't recognize that it's getting warming. Go figure.)
Now, next chore. Describe for us the reason why it's warming. Things don't just get hotter or colder "because they feel like it" or "it's something to do".
We need a physical reason....
Looks like muzzle flash out of a gun.Hope that one is pointed away from us.
some small cells poping up to the west of ya now
Big Rover scheduled to land August 5,2012 10:32pm Pacific Time. It's about 2 million miles from Mars right now. I think they will have live coverage on the Science Channel.
It's a very complex landing procedure.... Hope it goes OK....
Yes,I think they lost 2 missions.Very very complicated.
The Greenland ice sheet is melting at an ''unprecedented'' rate, according to NASA satellite data that shows 97 per cent of the vast mass is undergoing some form of melting.
''This was so extraordinary that at first I questioned the result: Was this real or was it due to a data error?'' a NASA researcher, Son Nghiem, said.
About half of the ice sheet usually shows signs of melting in a northern hemisphere summer, but the satellite data shows that between July 8 and July 12 the melt extended to cover almost all of Greenland.
It follows the breaking off this month of a giant chunk of ice from Greenland's Petermann Glacier. This formed an iceberg about twice the size of Manhattan, about 120 square kilometres in area.
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''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,'' NASA researchers said in a statement.
''Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile [3.2-kilometre] thick centre, experienced some degree of melting at its surface, according to measurements from three independent satellites analysed by NASA and university scientists.''
They described the event as being without precedent, because such a massive loss of ice has not been observed by humans, although estimates derived from studying old, compressed ice suggest that melts on this scale happen about once every 150 years.
''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,'' NASA said. ''About one-fifth of the annual sea-level rise experienced globally is attributed to the melting of the ice sheet.''
The manager of Australia's climate monitoring section at the Bureau of Meteorology, Karl Braganza, said the observation was a disturbing development.
''In terms of just one event taken in isolation, you can't tell much from it. We had a similar event back in the 1800s so it does happen from time to time,'' Dr Braganza said.
''But clearly there is a trend going on in the Arctic this century. We have warmer ocean temperatures, now what looks like particularly large reductions in sea ice, and large chunks of glaciers breaking off.''
The Arctic appeared to be locked in a vicious cycle, where rising concentrations of greenhouse gases meant higher temperatures, and more melting ice, which meant, in turn, that less of the sun's incoming heat was reflected away from the Earth.
''What's alarming to scientists is that we know the Arctic ice is a key feedback, and the warming in the Arctic has been slightly faster than was predicted 10 or 20 years ago,'' Dr Braganza said.
''This year, we measured CO2 emissions in the Arctic at above 400 parts per million for the first time. That's the first time it's been at that level in 3 million years. Back then, during the Pliocene period, the Greenland ice sheet wasn't a feature. Now we've taken the atmospheric chemistry back to that territory.''
The NASA statement said the huge melt had been driven by an unusual ''heat dome'' of relatively warm air that travelled across Greenland this month. The warm patch spiked just before July 18, and has now dissipated, they said.
SEVERE THUNDERSTORM WARNING
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MAY ALSO ACCOMPANY THESE DAMAGING WINDS.
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EMMETT AND HIGHLAND AROUND 145 AM EDT.
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THE WARNING INCLUDES AREAS SURROUNDING THESE LOCATIONS...
WEST BLOOMFIELD... WARREN... TROY...
STERLING HEIGHTS... ST. CLAIR SHORES... ST. CLAIR...
SOUTHFIELD... ROYAL OAK... ROMEO...
ROCHESTER... RICHMOND... PONTIAC...
OXFORD... ORTONVILLE... NEW BALTIMORE...
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