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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Thanks! However I have made more mistakes than I have hair on my head, however, and I have a full head of hair at 48+ yrs of age.
Lying and being hateful is a sincere waste of time. I find it so much easier to tell the truth than to lie. Do I lie, yes, I am human, BUT I try hard not to do so! As far as hatred goes, I have no patience for it!
Hemlock killed Socrates! Hatred/bitterness kills you from the inside out.
SNOW... FLORIDA...CHRISTMAS...
Man, just what I asked Santa for... happy dance happy dance :)
However, I admit, SADLY, it is quite prevelant in some areas of TX, even in what's almost 2010.
Go to bed...
:)
Dan, hmmm,
ok, G-d don't make mistakes --
but there are some really good improvements?
Grothar, right again!
watch it.. I saved that remark of yours about wanting snow....
I don't believe this quote is too far from what we have been witness to on the blog, and its application may be applied to other situations as well.
Passionate hatreds can give meaning and purpose to an empty life. These people haunted by the purposelessness of their lives try to find a new content not only by dedicating themselves to a holy cause but also by nursing a fanatical grievance. A mass movement offers them unlimited opportunities for battle.- Eric Hoffer.
ohhh I like that one... that would be a good avatar for shep
NASA Signs Agreement With ISRO For Indian Satellite
US space agency NASA has signed an agreement with ISRO to use data from Indian satellite Oceansat-2, for various American agencies for research activities, including weather forecasting.
Launched on September 23, 2009 using the Polar Satellite Launch Vehicle from Sriharikota, Oceansat-2; is designed to provide service continuity for operational users of the Ocean Colour Monitor (OCM) instrument on Oceansat-1.
The agreement with the Indian Space Research Organisation will lead to the use of data from Oceansat-2 for various US agencies for research, education and other activities of public good including weather forecasting.
The Letter of Intent in this regard was signed by Michael H Freilich, Director Earth Science Division, National Aeronautics and Space Administration; Mary E Kicza Assistant Administrator for Satellite and Information Science of the Oceanic and Atmospheric Administration; and R R Navalgund, Director, Space Application Centre, ISRO.
"I don't know if there'll be snow,
but have a cup of cheer!"
Say, do you know where/when
"A Christmas Story" is on this year?
Please don't tell me CBS -- sounded like it was "Crummy Butcher Sadists" for Rudolph!
ummmm....
dont you mean a cup of Urge? (:
Did Bordonaro see those students' writings?
Hilarious!
Catch 24 Hours of this holiday classic, starting Christmas Eve at 8/7c! TBS
Urge and Vodka lol
I think it will be expensive to get it here from Norway
SNOOPY SNOW!!
You saying he'll hafta splurge for some urge?
Say, Good Night, Gracie!!!!!!
LOL!
I've been meaning to ask --
Guess it's one for Grothar...what does "Urge" mean in Norwegian? Or does "Urge" still mean "Urge?" I mean...really...do Norwegians get the joke? Is this like bagpipes and kilts? Everyone gets the joke except the Scots?
LOL you guys crack me up
have a good one Grothar!
Awake in Maryland...That Rudolph trailor is probably from the mid 1960's.
Speaking of trailers.
Anyone notice in the trailer for "An Inconvienent Truth" there is nuke explosion?
Whats up with that?
Can't get it, never will.
Look at the shipping price! Are the bottles gold plated??
5 bottles $87.00 bucks! They're NUTS!!
Link
Nuclear winter
LOL they are filled with gold!
It is only sold in Norway and it means Urge!
The "cure" for GW would be worse than the disease!
Merry Christmas to T-Dude, eh? eh? (:
5 Bottles
USD: Decription:
$67.00 Shipping
$12.50 Bottles
$8.00 Packaging and fees
$87.50 Total
$17.50 Per unit
9 Bottles
USD: Decription:
$89.00 Shipping
$22.50 Bottles
$3.00 Packaging and fees
$114.50 Total
$12.72 Per unit
15 Bottles
USD: Decription:
$89.00 Shipping
$37.50 Bottles
$3.00 Packaging and fees
$129.50 Total
$8.63 Per unit
19 Bottles
USD: Decription:
$131.00 Shipping
$47.50 Bottles
$8.00 Packaging and fees
$186.50 Total
$9.82 Per unit
25 Bottles
USD: Decription:
$163.00 Shipping
$62.50 Bottles
$8.00 Packaging and fees
$233.50 Total
$9.34 Per unit
29 Bottles
USD: Decription:
$179.00 Shipping
$72.50 Bottles
$8.00 Packaging and fees
$259.50 Total
$8.95 Per unit
The General Electric Fantasy Hour 1964!!
Link
I could buy 2 bottles of Patron Tequila and by Vault with the change instead!!
LOL true, hmmm, but it just isnt the same :P
Mid 1960s? MOI?
Na Na Na Na Na Na Na Na Na Na Na
Hush, hush
I thought I heard her calling my name now
Hush, hush
Anybody wanna guess?
Hey, do you remember Kukla, Fran and Ollie??
4 of my friends and I are going to go in on 5 bottles. It will cost us each $17.50 a bottle. Yes that is expensive, but it is from Norway and they are 1.5 liter bottles :P
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