Why Southeast Greenland's glaciers have slown down since 2005
I'm in San Francisco for the annual meeting of the American Geophysical Union, the world's largest gathering of climate scientists. I saw ten or so great talks yesterday (and five really boring ones!) Here's a summary of the the most interesting talk I heard yesterday:
If you plan on owning ocean front property after the year 2050, you should pay close attention to the glaciers In Greenland. Greenland holds enough ice to raise global sea level by over 20 feet (6.5 meters), should its ice cap completely disintegrate--though such an event would likely take centuries to occur. Still, should the climate warm 2°C or more this century, partial melting of the Greenland Ice Sheet could readily raise global sea level by a meter or more by 2100. That's why scientists reacted with concern during 2003 - 2005, when all of the glaciers in southeastern Greenland accelerated in synchrony to speeds 30% to 210% faster than they had flowed in 1996. As they sped up, the glaciers began dumping huge amounts of ice into the ocean off the coast of southeast Greenland, more than doubling Greenland's contribution to global sea rise, to .57 mm/year. Would the glaciers keep accelerating, bringing about an increasing disintegration of the Greenland Ice Sheet? Nobody knew, since computer models of glacial dynamics were (and still are) in a primitive state.
Figure 1. Helheim Glacier in southeast Greenland, in three images captured in 2004, 2005, and 2006. The glacier accelerated significantly in 2005, and the face of the glacier retreated 5 km inland (middle frame) compared to 2004. However, by the summer of 2006, the acceleration ceased, the the glacier returned back to its 2004 position. Image credit: Ian Howat, University of Washington.
Well, it turned out that 2005 was the peak of the glacial acceleration event. The glaciers in southeast Greenland have returned to where they were eight or nine years ago--still causing a net loss of mass that is raising global sea level, but not as fast as in 2003 - 2005. In a talk titled, "Ocean regulation of glacier dynamics in south-east Greenland and implication for ice sheet mass changes", Tavi Murray and colleagues from the UK's Swansea University presented a plausible theory for why this strange synchronous speed-up and slow-down occurred. Using satellite, aircraft, and surface observations, the researchers found that air temperatures in the region did not vary much over 2003 - 2005 (Figure 2). Thus, a major increase in temperature could be ruled out as the cause of the glacier surge. However, study of the ocean temperatures near the coast revealed strong clues that ocean currents were responsible for the surge.
Figure 2. Ocean currents off the east coast of Greenland feature the cold East Greenland Coastal Current flowing north to south (white arrows) and the warm Irminger Current flowing south to north (red arrows). Image credit: Arctic Climate Impact Assessment.
Ordinarily, the southeast coast of Greenland features a cold water current flowing north to south, called the East Greenland Coastal Current (EGCC). Much of the cold water for this current is supplied by melting of the 14 glaciers in southeast Greenland that empty into the sea (two of these glaciers, Kangerdlugssuaq and Helheim, represent 35% of east Greenland's total glacial discharge). A few hundred kilometers offshore, a warm water current called the Irminger Current flows the opposite direction, bringing warm water from the North Atlantic northward. In 2003, it happened that weather conditions over Greenland brought an unusually low amount of run-off of precipitation. With little new mass pushing the glaciers seaward, the glaciers responded by greatly reducing the amount of ice they dumped into the ocean by the shore. As a result, the East Greenland Coastal Current slowed down and warmed, which allowed the warm Irminger Current to advance towards the coast, warming the coastal waters even more. All that warm water near the coast began melting the glaciers where they reached the sea, causing the glaciers all along the southeast coast of Greenland to accelerate and rapidly thin between 2003 - 2005. By 2006, the thinning glaciers had dumped so much new ice into the ocean near the coast that the waters cooled and the East Greenland Coastal Current re-established itself. This cooled the glaciers at their marine termination points and slowed down the glacial surge, putting the glaciers back where they had been before 2003. This is a classic example of a negative feedback process--a change in weather conditions which generates a response, but the response creates conditions that tend to dampen the response.
Figure 3. Average temperatures for the only station in southeast Greenland with a century-long temperature record, Angmagssalik (called Ammassalik on the map in Figure 2). Temperatures in southeast Greenland during the 1930s and 1940s were similar to today's temperatures, suggesting that glacial surges like we witnessed in 2005 may have also occurred in the 1930s and 1940s, before we had monitoring capability. Image credit: NASA Goddard.
Commentary
As I commented in my previous post, Arctic sea ice loss appears to have created a new atmospheric circulation pattern that brings more warm air in the Arctic, creating a positive feedback loop that causes even more sea ice loss. This positive feedback loop was a bad news surprise that our climate models did not predict. Now we have evidence of a good news surprise that no model predicted--a negative feedback loop that acts to keep the southeast portion of Greenland's Ice Sheet from runaway glacial acceleration. We can expect many more surprises--good and bad--over the coming decades, as our climate responds to the huge shove human activities are giving it.
Ricky Rood in Copenhagen
Our Climate Change expert, Dr. Ricky Rood, is in Copenhagen for the COP15 climate change treaty negotiations. His latest post, called Have you no sense of decency, sir, at long last? makes for very interesting reading on how the U.S. is "wasting its intellect and time on disruptions designed to play to people at home".
Next post
I'll have another post from the AGU meeting Thursday or Friday this week.
Jeff Masters
Reader Comments
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...Potential for severe storms and coastal hazards on Friday...An area of low pressure is expected to develop over the western Gulf of Mexico on Thursday. This low is then expected to intensify as it moves east across the northern Gulf Coast Thursday night and then across the northern Florida Peninsula on Friday. Ahead of the low an increasing moist southerly wind flow will develop over west central and southwest Florida Thursday night and Friday. This increasing southerly flow will help to build seas over the adjacent Gulf waters. The building seas will generate large breaking waves and dangerous rip currents along and high surf along area beaches on Friday with above normal tides possibly causing some coastal flooding at times of high tide on Friday. The strong southerly wind flow and increasing seas will make for hazardous boating conditions over the Gulf waters and inland water ways...and mariners may want to postpone trips into the Gulf until conditions improve.
As the low pressure area approaches a more favorable environment for severe storms will develop over west central and southwest Florida late Thursday night into Friday. As the low moves east northeast across the Northern Peninsula during the day on Friday a squall line will likely develop along and ahead of a trailing cold front over the adjacent Gulf waters early Friday morning with the line of storms likely to affect the region from mid morning through the afternoon and early evening hours. At the current time sufficient low level moisture combined with strong prefrontal convergence...sufficient deep layered shear and a strong low level jet may help to produce organized storms containing damaging winds and possible isolated tornadoes and marine waterspouts. In addition some locally heavy rainfall and deadly lightning strikes will accompany the storms as they move across the region. In the wake of the cold front a brisk northwesterly wind flow will usher in a much cooler and drier air mass with below normal temperatures expected across the region through the upcoming weekend...with some near freezing temperatures possible over the Nature Coast by Sunday night into Monday.
In addition to the cooler temperatures the brisk northwest wind flow will keep sea elevated over the adjacent Gulf waters with hazardous boating conditions continuing.
All residents and visitors of west central and southwest Florida should remain alert to rapidly changing weather conditions during Thursday night into Friday. Stay tuned to NOAA Weather Radio or your local media for further updates on this developing weather situation.
GFS 12-28-09, 276 HRS out, 2M temp, 10M wind
For a larger pic, right click on image, right click on properties, cut and paste URL address into your browser and voila' full image!!!
Well I think if yall were to get any snow this will be the year.
Hopefully this holds true. Ill be watching it.
drak i love you hahahaha :D
by Joe Bastardi
Ahhh, sookie sookie now. Giggles, just kiddn
Well its only Decemeber. Here Feb is "usually" our coldest month.
I think usually 3 times a day or twice.
Don't they have to be weather related and sent into qualify as wonder photos? Oh, and BTW, I now hate you. All that hair, and still dark.
Please explain how melting all the ice on Greenland could possibly raise sea levels by 20 feet!
I must be mathematically challenged, but my figures indicate that such a result would require the ice sheet on Greenland to be uniformly 22,367 feet thick over the ENTIRE island!
I have my doubts, so someone, Please help me with my math.
If the area of Earth's oceans is 935,327,486 sq miles and the area of Greenland is 836,330 sq miles, a 20 foot rise (0.003787879 miles) in the ocean level would equal a 22,367 foot thickness of Greenland ice. That is ignoring the fact that ice is less dense than water and therefore would need to be even thicker.
I must have made some mistake.
I know Joe Bastardi is not the "world's most loved" weatherman/blogger in the world, especially on WU! Here is a link, however below to his forecast for late Dec 2009:
Link
I am getting very excited about this!!
I have this feeling, between 12-26 and 12-31-09, when all is said and done 75% of the CONUS will be covered in snow!!
Here is a link which might help explain it. Lot of ice underneath too! The ice is compressed.
Link
I'm not sure if anyone has already posted this information, but if not, some of you might find this interesting. I watched a show about this on Discovery called Project Earth.
From telegraph.co.uk: "Wrapping Greenland in reflective blankets - Rising sea levels are threatening the planet but a glaciologist has devised a way to prevent glaciers from melting further - by wrapping them in a reflective blanket. "
Here's a link to the rest of the article and also a video: Link
that would be epic
Never mind the blankets, I would love to see those pillows. I think only the ladies will get this pun, but here goes. I think the whole thing is a big "sham"!
Yeah, what is point of pillows one doesn't lay their head upon? Waste of natural resources, if you ask me...
The GFS 18Z models are downloading on their website now. They've downloaded the first 54 hrs, 12 more days to load.There is SO much info, so it'll be a lil' while yet!
The NWS in Dallas-Ft Worth mentioned the 12Z GFS run in the long range forecast, stating, "things will be quite interesting if the 12Z GFS verifies"! BUT, they're chicken and did NOT metion that that run calls for a major snowstorm in N TX on 12-28!!
Wow, that dude looks somewhat scary in a still image...
LOL
Since my mother's family lived in the South, she used to sing a song like "Lay your head against my pillow......" I think the song was "For the good times. Are you familiar with it? Maybe they can play it when they are sewing the blanket and pillows. LOL
GFS 18Z loaded through 66 hrs, 312 hrs more info to load! Link to the NAM and GFS models below for all who are interested!!!
Link
wow!
Ran the first 84hrs of 18Z GFS, looks like the Mid Atlantic Snowstorm event is still ON!!
96 HRS 12-20-09 2M Temp, 10M Wind 18Z GFS
The air has been driven out of the ice, making it clear. While it is more dense than the white ice, the ice still has less density than water. One foot of highly compressed ice does not equal more than a foot of water when melted, it will always equal less than one foot of water.
This could possibly be the start of the blanket for the ice caps. They seem to be doing it in North Dakota.
NO, that would be MODIKI EL NINO!! Mid PAC warms up, dumps loads of moisture on the Sub Tropical Jet AND allows ARCTIC air to invade the US!!!
wow and a stronger storm than last run
Care to share of what is shows?
Viewing: 951 - 1001
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