Why Southeast Greenland's glaciers have slown down since 2005

By: Dr. Jeff Masters , 3:57 PM GMT on December 15, 2009

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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

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I envy you your snowfall...nothing quite like being snowed in (that is, as long as you have supplies)

Howdy, folks!
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Quoting pinehurstnc:
hello all. and merry christmas to all.. just want to ask 1 ? that will prolly be asked a 100times, was lookin at some model output , what chance is there for snow here in central nc this weekend tyia greg


READ LINK :o) And enjoy your snowstorm!!!



Link
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Quoting Jeff9641:


The El-Nino is still strenghtening as well. I believe it is supposed to peak in February.


This El Nino is warming the C PAC. So the Sub-Tropical Jet is being supercharged with warm, moist, tropical mositure, while Arctic intrusions still take place over Canada and the CONUS from time to time, producing prolific rain/snow producers around the counrty. Now with the NEG AO and NEG NAO, even more cold air is going to be dumped into the US, producing he possibilities for S Plains, SE US, Mid Atlantic, NE and New England Snowstorms!!!
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hello all. and merry christmas to all.. just want to ask 1 ? that will prolly be asked a 100times, was lookin at some model output , what chance is there for snow here in central nc this weekend tyia greg
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Looks like the moderate EL NINO, Modiki style is going ti give many parts of the CONUS something to remember!

Link 18Z GFS model current through 12-22-09 below:

Link
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Flash Flood Watch now in effect for New Orleans, only like the 10th one this month
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120HRS 12-21-09 Surface temps/winds (2M air/10M wind) 18Z GFS:

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Quoting Bordonaro:


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



wow and a stronger storm than last run
Member Since: September 6, 2007 Posts: 0 Comments: 6672
Quoting tornadodude:


that would be epic


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!!!
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Quoting Grothar:


Here is a link which might help explain it. Lot of ice underneath too! The ice is compressed.

Link

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.


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Quoting tornadodude:


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

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Quoting Bordonaro:


GFS 18Z loaded through 66 hrs, 312 hrs more info to load!


wow!
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:
;)


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
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``slown''?!?
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Quoting Grothar:
My sister who is 83 is getting a few wisps of gray, but she is not that attractive anyway, so who cares.


LOL
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:


LOL I'm by no means a lady, but I got it.



oh you meant pillow..... :P jk

Wow, that dude looks somewhat scary in a still image...
Member Since: August 16, 2007 Posts: 6 Comments: 12463
;)
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting NEwxguy:
models keep hinting at something around the holidays.


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!!
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Quoting Grothar:


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...
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting Bordonaro:


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!!



that would be epic
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Ok, I'm going to post this again just because I found it surprising that I didn't see any responses to this, even though it couldn't be more on topic. I figured for sure someone spoiling for a fight would comment on whether it's frivolous or a good idea. I know most of my posts go largely unnoticed, but geez... anyway, here it is, AGAIN.

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
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models keep hinting at something around the holidays.
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Quoting tornadodude:


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!!

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Quoting Bordonaro:
1800Z GFS models are being loaded up, as I type for the current-16 day period!!


I am getting very excited about this!!
Member Since: June 28, 2006 Posts: 25 Comments: 8360
1800Z GFS models are being loaded up, as I type for the current-16 day period!!
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The cold front on Friday could cause severe storms in western Cuba.
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Quoting xcool:
The December to Remember is about to fire up in a way that makes this holiday season the most memorable one in many a year weatherwise.

by Joe Bastardi


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
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Hey!

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.
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I just want it to drop out of the 80's so it doesn't feel like were still in late Sept.. lol
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This is the GFS forecast for the snow depth through next week Monday. Glad i'll be up north :)





Member Since: October 28, 2006 Posts: 57 Comments: 30620
Quoting Grothar:
Yo! Grothar needs some assistance. I just uploaded some pictures, but they do not appear as Wunderphotos, just My pictures. How do I get them there?

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.
Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting VAbeachhurricanes:
How often are NWS local forecasts updated?


I think usually 3 times a day or twice.
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How often are NWS local forecasts updated?
Member Since: September 6, 2007 Posts: 0 Comments: 6672
TTYL, I have to go to work. Everyone play nice and continue with the pretty snow map/forecasts.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Quoting Jeff9641:


I agree the problem is it has been difficult to get cold airmasses into the penisula of Florida. We've been getting a lot of rain but that's it.

Well its only Decemeber. Here Feb is "usually" our coldest month.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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