Why Southeast Greenland's glaciers have slown down since 2005

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

Share this Blog
4
+

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

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1263 - 1213

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

1263. usa777
Does anyone have any predictions for snowfall this weekend in the Maryland area?
Member Since: Posts: Comments:
man...

the gfs wants to dump on us in central va....local mets are saying anywhere from 5-10 inches in the area...gfs/nam wanna give us 10-16...i think ill believe anything over 5 when i see it...
Member Since: Posts: Comments:
1260. dsauder
EstherD,

Thank you so much! I did screw up somewhere and I apologise to Dr Masters and all.

Quoting EstherD:
Here's the correct calculation... Area of ocean is 361,132,000 sq km. 20 feet rise = 0.006096 km. Meltwater volume is therefore 2,201,460 cu km. Area of Greenland is 2,166,086 sq km. Average ice thickness is therefore 1.016 km = 0.63 mi = 3,333 ft.

I'll need to tune up my calculator technique before I try that again! I should have left the units in metric but I just liked the old english system better. Boo Hoo Hoo.
Member Since: Posts: Comments:
I don't no if the shock of everything has hit me yet. I'm like, did that really happen?
Member Since: Posts: Comments:
Quoting AussieStorm:

Well,,, today got to a top of 42C(107.6F) and the day has ended with thunderstorms. Well i am driving home from work and its raining pretty hard. then ***FLASH*** .car just shuts down, dead, no battery no nothing. A car pulls up beside me as i'm hopping out to see whats wrong... said he saw my car get struck by lightening and was stopping to see if i was ok. I told him my car wont start. He said, I'm not surprised, it got struck. I was like... no way, your joking. So he gave me a jump start. and asked again if I was alright which i assured him I was, and we both drove off.


Since it appears that you are unharmed - that is an awesome story man!
Member Since: Posts: Comments:


AOI

AOI

AOI

AOI

Humor in Comments
Member Since: Posts: Comments:
Quoting atmoaggie:

You numbers do check out. (the calculations anyway)

Maybe the 20 feet includes more than just Greenland...

Good catch, EstherD! What is the correct area in sq miles for the oceans?


Do not check their math... or their facts, they are counting on blind obedience to what they say. Its hard to lead the sheep to the promised land... if they start to think for themselves.

Member Since: Posts: Comments:
Quoting Orcasystems:


Time to buy a Lotto ticket :)

that makes it twice i have been struck by lightening, 3rd time i think i wont be as fortunate.
Member Since: Posts: Comments:
Quoting AussieStorm:

Well,,, today got to a top of 42C(107.6F) and the day has ended with thunderstorms. Well i am driving home from work and its raining pretty hard. then ***FLASH*** .car just shuts down, dead, no battery no nothing. A car pulls up beside me as i'm hopping out to see whats wrong... said he saw my car get struck by lightening and was stopping to see if i was ok. I told him my car wont start. He said, I'm not surprised, it got struck. I was like... no way, your joking. So he gave me a jump start. and asked again if I was alright which i assured him I was, and we both drove off.


Time to buy a Lotto ticket :)
Member Since: Posts: Comments:
Quoting PensacolaDoug:



I'll bite.
Wassup Ausie?

Well,,, today got to a top of 42C(107.6F) and the day has ended with thunderstorms. Well i am driving home from work and its raining pretty hard. then ***FLASH*** .car just shuts down, dead, no battery no nothing. A car pulls up beside me as i'm hopping out to see whats wrong... said he saw my car get struck by lightening and was stopping to see if i was ok. I told him my car wont start. He said, I'm not surprised, it got struck. I was like... no way, your joking. So he gave me a jump start. and asked again if I was alright which i assured him I was, and we both drove off.
Member Since: Posts: Comments:
Quoting dsauder:
Patrap,

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 (4.22356 mile) thickness of Greenland ice.

That is ignoring the fact that ice is less dense than water and therefore would need to be even thicker. It also ignores the fact that a 20 foot rise in sea level would increase the area of the oceans by some significant factor.

Please help me. What, specifically, is wrong with that math?

Your numbers do check out. (the calculations anyway)

Maybe the 20 feet includes more than just Greenland...

Good catch, EstherD! What is the correct area in sq miles for the oceans?
Member Since: Posts: Comments:
1246. NEwxguy
These east coast nor'easters are always tricky,a deviation of 50 or 75 miles makes so much difference on who gets dumped on and who misses.Looks like it will be sharp cutoff on qpf too.
Member Since: September 6, 2007 Posts: 878 Comments: 15739
Quoting Jeff9641:
Yes, as it gets to that point this storm could deepen fast as it heads toward north Florida. This will set up a potentially dangerous Christmas Eve night for Florida in regards to the severe weather potential.



The divers always concern me. Look at St. Louis a few years back.
1244. EstherD
Quoting dsauder:
... If the area of Earth's oceans is 935,327,486 sq miles ...


Where did you get that number? According to Wikipedia, the area of the earth's oceans is 361,132,000 sq km, which is 139,433,845 sq mi. Using the wrong value for ocean area is the reason your math is wrong by nearly a factor of 10. (Think you might have blown the conversion of sq km to sq mi -- multiplied by 2.6 instead of dividing by 2.6 ?)

Here's the correct calculation... Area of ocean is 361,132,000 sq km. 20 feet rise = 0.006096 km. Meltwater volume is therefore 2,201,460 cu km. Area of Greenland is 2,166,086 sq km. Average ice thickness is therefore 1.016 km = 0.63 mi = 3,333 ft.

That jives with the facts... "The ice cap averages about 5,000 feet (1,500 meters) in thickness, but can be as thick as 14,000 feet (4,300 meters)."
Member Since: Posts: Comments:
Quoting AussieStorm:
Good evening all, well what can i say, its happened to me again.



I'll bite.
Wassup Aussie?
Member Since: Posts: Comments:
Good morning all! Pat, are you a man of constant sorrow? That low is looking impressive this AM.
Member Since: Posts: Comments:
1240. Drakoen
The ECMWF, GGEM, GFS, AND UKMET have come into better agreement with the timing and track of the Nor'easter that will affect the eastern seaboard. While the GFS and UKMET has the most northern and westward track keeping the system adjacent to the Delmarva and Long island areas, the ECMWF and GGEM continue to eject the system NE and ENE before the system makes it that far north. Regardless, concerning the Mid-Atlantic states, look for widespread snow fall accumulations with snow ratios between 10:1 to 15:1 with the highest rations near the Appalachians and then back towards Virginia, Maryland, and the Delmarva with good omega forcing (mid level dynamics) for dense snowfall accumulations. Widespread area of over a foot of snow in the snow growth region.



Member Since: Posts: Comments:
1239. dsauder
Patrap,

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 (4.22356 mile) thickness of Greenland ice.

That is ignoring the fact that ice is less dense than water and therefore would need to be even thicker. It also ignores the fact that a 20 foot rise in sea level would increase the area of the oceans by some significant factor.

Please help me. What, specifically, is wrong with that math?
Member Since: Posts: Comments:
Quoting Jeff9641:


I don't think it will get a name due to so much cold getting involved into the system. It will be a strong storm though. Next weeks storm could be stronger as it dives into the gulf and then up across north Florida.



This One?

Good evening all, well what can i say, its happened to me again.
Member Since: Posts: Comments:
1234. NEwxguy
That gulf low is going to dump some snow on someone in the mid-atlantic,and going to be a close call for me.
Member Since: September 6, 2007 Posts: 878 Comments: 15739
Might we get a name out of this one?
1229. Patrap
Beats my Meade 4.5 Reflector, easily.
Member Since: July 3, 2005 Posts: 424 Comments: 128344
1228. dsauder
Almost!
Member Since: Posts: Comments:
1227. Patrap
Well..the refractor is cool.

Can ya see Santa?

Your math is way off.

The Greenland Water/ice content is a easily found number,and is published in over 130 peer-reviewed papers.

Member Since: July 3, 2005 Posts: 424 Comments: 128344
1226. dsauder
I thought the purpose of this blog was to discuss Dr Master's comments and the whole issue of global weather in general.

How comes there is so much discussion about viking helmets when the very essay under discussion contains the following quote, (second sentence in the second paragraph)

"Greenland holds enough ice to raise global sea level by over 20 feet (6.5 meters), should its ice cap completely disintegrate"

I repeat my question from #971,

"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"!


That is, even if it were FLAT, which it is not. And, No, the weight of the ice does not push the entire land surface down to sea level or below.

I maintain that there is just not enough ice on Greenland to do what is being claimed.

WE are being HOODWINKED by so called data that very few take the time to check and challenge!
Does no one care that we are being fed a bunch of hot air? Or does everyone have their head in the sand? No wonder the globe is warming!

Or is it?
Member Since: Posts: Comments:
Good Mornin'

Thanks Patrap.

I got to ask a question of the President of the Maldives, at the climate change conference on Monday via oneclimate.net.
It was stunning to hear that they aren't making plans to move, given that sea level is rising. It seems so fatalistic, since sea level will rise with or without climate change and the fringe atolls will eventually go under if the coral doesn't keep up.
What a huge catch 22, they need tourism to survive but air travel produces greenhouse gasses that raise sea level faster.
Member Since: Posts: Comments:
1221. Patrap
G'morning unf97,& doug..the Se US may have Many surprises in the next 10 days if the GFS verifies thru the period as forecasted now.
Member Since: July 3, 2005 Posts: 424 Comments: 128344
G'mornin' all!
Member Since: Posts: Comments:
1219. Patrap
Current US Surface Map.



Member Since: July 3, 2005 Posts: 424 Comments: 128344
1218. unf97
Good morning Patrap.

Your post of the GOM IR really shows our Low pressure area beginning to spin up. This Low really has a potential to rapidly intensify, which the GFS is forecasting. This one really will be interesting to watch. Also, my area in NE FL may get warm sectored just enough as the system moves through during the next 24-36 hours to possibly generate strong/severe storms. I will be watching that very carefully. This system definitely will be another signifcant rainfall event with flood concerns in S AL, panhandle of FL, and Southern Ga.

Looks like the models finally fell in line with this current GOM Low with my thinking a couple of days ago to bring snow to NC and VA. Get ready for a good band of snow from the NC foothills and piedmont along aand north of a line from Charlotte to Raleigh to interior Virginia. Winter storm watches already posted.

Looks like very strong cold air advection behind this Low will finally bring the season's first freeze to my area either Sunday or Monday morning. Expecting low 30s interior areas NE FL, with possible upper 20s by Monday morning.
Member Since: Posts: Comments:
1217. Patrap
Quoting biff4ugo:
Patrap,
On the animation 1211, you posted there is a big triangular "low level" wedge of clouds that looks stationary even with the speedy winds aloft. Kinda like a forest fire smoke plume but in the middle of the Gulf.
24N, 93.5W
What is this?
Is it just a suface vapor boil under heavy wind sheer that would otherwise look like a more typical tropical wave as seen at 17N, 85W?
Or is it something stationary?


On the GOM IR Loop I presume,..

Low Level..or near surface clouds I believe.

Or surface flow one could say,..
Member Since: July 3, 2005 Posts: 424 Comments: 128344
Patrap,
On the animation 1211, you posted there is a big triangular "low level" wedge of clouds that looks stationary even with the speedy winds aloft. Kinda like a forest fire smoke plume but in the middle of the Gulf.
24N, 93.5W
What is this?
Is it just a suface vapor boil under heavy wind sheer that would otherwise look like a more typical tropical wave as seen at 17N, 85W?
Or is it something stationary?
Member Since: Posts: Comments:
1215. Patrap
Just call us the Soggy Bottom Boyz
Member Since: July 3, 2005 Posts: 424 Comments: 128344
Member Since: Posts: Comments:
I feel for yall Pat. Something like 25" of rain for Dec. in the N.O. WOW
&
Its pretty soggy here in Lafayette too.
Member Since: Posts: Comments:

Viewing: 1263 - 1213

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.