Two new studies summarized in a news article in Science magazine point to wind-induced circulation changes in the ocean as the dominant cause of the recent ice losses through the glaciers draining both the Greenland and West Antarctic ice sheets, not ‘global warming.’
The two stuides referred to are:
‘Acceleration of Jakobshavn Isbræ triggered by warm subsurface ocean waters’ by Holland et al, published in Nature Geoscience.
The Abstract states:
Observations over the past decades show a rapid acceleration of several outlet glaciers in Greenland and Antarctica1. One of the largest changes is a sudden switch of Jakobshavn Isbræ, a large outlet glacier feeding a deep-ocean fjord on Greenland’s west coast, from slow thickening to rapid thinning2 in 1997, associated with a doubling in glacier velocity3. Suggested explanations for the speed-up of Jakobshavn Isbræ include increased lubrication of the ice-bedrock interface as more meltwater has drained to the glacier bed during recent warmer summers4 and weakening and break-up of the floating ice tongue that buttressed the glacier5. Here we present hydrographic data that show a sudden increase in subsurface ocean temperature in 1997 along the entire west coast of Greenland, suggesting that the changes in Jakobshavn Isbræ were instead triggered by the arrival of relatively warm water originating from the Irminger Sea near Iceland. We trace these oceanic changes back to changes in the atmospheric circulation in the North Atlantic region. We conclude that the prediction of future rapid dynamic responses of other outlet glaciers to climate change will require an improved understanding of the effect of changes in regional ocean and atmosphere circulation on the delivery of warm subsurface waters to the periphery of the ice sheets.
And:
‘Modelling Circumpolar Deep Water intrusions on the Amundsen Sea continental shelf, Antarctica’ by Thoma et al, published in GRL.
The Abstract states:
Results are presented from an isopycnic coordinate model of ocean circulation in the Amundsen Sea, focusing on the delivery of Circumpolar Deep Water (CDW) to the inner continental shelf around Pine Island Bay. The warmest waters to reach this region are channeled through a submarine trough, accessed via bathymetric irregularities along the shelf break. Temporal variability in the influx of CDW is related to regional wind forcing. Easterly winds over the shelf edge change to westerlies when the Amundsen Sea Low migrates west and south in winter/spring. This drives seasonal on-shelf flow, while inter-annual changes in the wind forcing lead to inflow variability on a decadal timescale. A modelled period of warming following low CDW influx in the late 1980’s and early 1990’s coincides with a period of observed thinning and acceleration of Pine Island Glacier.
Yes, Mike, I believe you can see the Gakkel Ridge represented on the animation. There is persistently thinner ice over the ridge than elsewhere. I know there was a discrete event in 1999, but whether the whole ridge has been more active or not lately, I don’t know. Obviously, the vulcanism along that ridge is acting like a bunsen burner at the bottom of a basin. I suspect the heat from that vulcanism is not so easily dispersed as in the less circumscribed oceans.
Thanks, DR. Andy Revkin had this animation last summer and we all went round and round the DotEarth over it in several posts. That’s how I know there were clouds overlying the ‘great blue spot’, so the photographic record is inadequate for determining whether the ice melted there or not. I’d like to know if they were ordinary Arctic clouds, or the sort of clouds that would appear over open water or even just over warmer ice. By the animation, the ice suddenly thinned there, while intact ice around it did not, which suggests that winds and currents might not have had much to do with the generation of the ‘great blue spot’ of 1999.
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Arctic ice floats on water and about 90 percent of the ice is under water.
As a zeroth-order estimate of where to look for the dominant physical phenomena and processes that govern both the thermal and structural responses of the ice I say look under the surface. Not above the surface.
Additionally I have read that the surface of the ice might be covered with soot and stuff, thus increasing the direct radiative energy input component to energy (and thus the ice mass) balance for the ice. Look there, too.
Full disclosure: I am not a Certified Climatologist.
http://geology.geoscienceworld.org/cgi/content/abstract/29/12/1139
“Seismic activity began in mid-January (1999) and continued vigorously for three months; a reduced rate of activity persisted for an additional four months or more. In total, 252 events were large enough to be recorded on global seismic networks. Although a limited number of volcanic-spreading events have been observed globally, the duration and magnitude of the Gakkel Ridge swarm, when compared with volcanic seismicity at ridges spreading at intermediate and fast spreading rates, suggest that a negative power-law relationship may exist between these parameters and spreading rate.”
I wonder if anyone is watching the more recent seismic activity.
Temperatures in the interior of the Greenland ice sheet are averaging -44F (-42C) this month, starting one week after the end of summer.
http://www.wunderground.com/history/station/04416/2008/10/4/MonthlyHistory.html
Ice extent nearly back to 2005 levels.
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent.png
Has anyone else seen this posting on the 2nd October on the NSIDC website?
“The 2008 season strongly reinforces the thirty-year downward trend in Arctic ice extent. The 2008 September low was 34% below the long-term average from 1979 to 2000 and only 9% greater than the 2007 record (Figure 2). Because the 2008 low was so far below the September average, the negative trend in September extent has been pulled downward, from –10.7 % per decade to –11.7 % per decade (Figure 3).
NSIDC Senior Scientist Mark Serreze said, “When you look at the sharp decline that we’ve seen over the past thirty years, a ‘recovery’ from lowest to second lowest is no recovery at all. Both within and beyond the Arctic, the implications of the decline are enormous.” ”
With an observation such as that, how can he possibly expect to be taken seriously?
“When you look at the sharp decline we have seen over the past 30 years, a recovery from lowest to second lowest is no recovery at all,” Serreze said.
The recovery is not a recovery.
Droughts caused by Global Warming. Increased rainfall caused by Global Warming. Warming is warming. Cooling is warming. Wind is because of warming. Lack of wind is because of warming.
Is there nothing that Global Warming can’t do?
See here for a list of some of the things caused by Global Warming:
http://www.numberwatch.co.uk/warmlist.htm
I’ve always thought that there had to be more causes of climatic shift than just CO2. Vulcanism, magnetosphere variation, wind and current pattern shifts all seem to play a far greater part than just a trace atmospheric gas.
To me, one trace atmospheric gas alone could not be responsible for the increases and decreases in temperature we see. CO2 warming as outlined by the IPCC and the Gore AGW faction always struck me rather like trying to boil a bucket of water using your kid sisters toy hairdryer. Try it sometime when you’ve got a year to waste.
And here’s something from the other side of the world.
Penguins in Brazil
They’re now beating the drum for record low for arctic sea ice in 2009.
From Arctic Ice in “Death Spiral,” Is Near Record Low:
The ice is in a “death spiral” and may disappear in the summers within a couple of decades, according to Mark Serreze, an Arctic climate expert at the National Snow and Ice Data Center in Boulder, Colorado.
“With the climate feedbacks kicking in,” Serreze said by email, “we’ll lose the summer ice cover probably by the year 2030.”
“The remarkable thing about this summer is that we got all the way down to second lowest without especially favorable atmospheric patterns that would hasten melt,” Serreze said.
This near record low in 2008 was expected because warming has melted much of the older ice pack, resulting in thinner sea ice, which melts rapidly.
So even without special conditions like those seen in 2007, next summer could set a new record low, [Sheldon Drobot, a climate scientist at the University of Colorado, Boulder] added.
Sheldon D Robot
Good robot. Sleep now. The teat of funding is here.
Lucky for you!
Why do they use the average for 1979-2000 for comparison to 2008 instead of an average from 1979 to 2005 or pick another year?
I just love these long range predictions. Serreze is learning from the climate modelers. I predict that in thirty years no one will remember this “death spiral”.
Mike Bryant
Where is the over/under action on 2009 Arctic sea ice extent?
I’m going with the over.
Anthony et al: Sorry for contributing late. Based on the ERSST.v3 version of Arctic SSTs, they skyrocketed after the 1997/98 El Nino. Since there’s up to a year lag between ENSO events and peak Arctic response, we may not see the results of last winter’s La Nina until this winter.
Arctic, Northern Hemisphere, and Global SST anomalies from Jan 1978 to April 2008:
http://i35.tinypic.com/330e3ae.jpg
Arctic, Northern Hemisphere, and Global SST anomalies from Jan 1880 to April 2008:
http://i36.tinypic.com/1znpjiq.jpg
The ERSST.v2 version of Arctic SSTs had a much flatter curve in recent years, no anomalous rise. I covered it in this post:
http://bobtisdale.blogspot.com/2008/10/ersstv3-version-of-arctic-ocean-sst.html
Whatever the cause of the recent ice melt, it surely doesn’t appear to have an anthropogenic basis.
Regards
Why is the animation not filling in the NW passage? Looks as though I could make a winter trip in my skiff with ports of call at every village in Northern Canada!
[…] “Two new studies… point to wind-induced circulation changes in the ocean as the dominant… […]
I have doubts about volcanic activity affecting the icecap (that takes a lot of heat!) but there has been some seismic activity up there detected. A search from 90,0 with 1000 km radius does show assorted shaking. Some seem to be near the Ridge. http://neic.usgs.gov/neis/epic/epic_circ.html
As those with the patience to read my ramblings will know, I am just a simple lawyer from London with no scientific training or experience. So, I want to make a wholly unscientific observation.
When the sun shines on me I feel warmer. When a cloud comes over to block the sun I feel cooler. When a cold wind blows I feel colder. When a warm wind blows I feel warmer. I know that the hairs on my arms (but no longer, sadly, the top of my head) have an effect on my experience of wind, fortunately I have lots of flabby pink chins to allow the delights of warm and cold winds to be experienced by several square feet of minimally haired flesh.
You can produce any number of fancy theories and intricate mathematical equations, but none will persuade me to discard the certain knowledge of my physical experience.
Every day starts with the world around FatBigot Towers at a certain temperature. The sun (or lack of) and wind (or lack of) dictate how the temperature of my little world changes. Cars, air conditioning units (not that we have many of those over here) and other random sources of heat might make a small difference but only small.
That being the case for my modest hovel in Highbury, North London, I see no reason why it should not be the same for everywhere else on the planet, after all, where I live is not an exception it is an example.
It goes without saying that when Mr Sun has shone on me other parts of the planet will want to share in the glory, so I allow the little heaty-things to bounce up. But even when they have done so and they sit up above throbbing with excitement, a warm wind will be the thing that melts my ice cream on a cloudy day and a cold wind will be the thing that makes me put on an extra layer of clothing when the sun is shining.
The ice up at the top bit of our planet is no different from me. The sun and the winds will determine whether it feels warm or cold. AGW theory is one step removed. It is only responsible for the melting/freezing if it enhances or reduces either the effect of the sun or the effect of the wind.
Just a layman’s thought; I know nothing, I have not been peer-reviewed.
Classic: http://abcnews.go.com/Technology/story?id=5941683&page=1
“Sea ice at the top of the planet has apparently reached the lowest *volume* ever recorded,”
Notice the shift from extent and area. Can’t win? Just change the rules. It’s like playing Calvinball.
MattN, From the article you linked to above this quote:
“We’re pretty confident this is a record low,” said Walt Meier, a research scientist at the center.
I guess since he is “pretty confident” that it’s a record low that completely justifies the screeching headline “Arctic Sea Ice Shrinks to Record Low”
I’m afraid that government subsidies to these entertainers may be headed for a “death spiral”.
[…] what is actually causing ice sheet loss in Greenland and the west Antarctic? Anthony Watts has the […]
I presume that all this warming and increase in Ocean depth, is the natural course intended for the entirety of the whole of big bang/creation.
Based on history, the Ocean waters are slowly increasing as the Ice melts.
If we Research history, as I did this morning, it is just common to the history of earth to be constantly warming.
The early wonderers that slowly drifted from where ever the first humans orignated, were able to walk from one continent to another. Because there was more land. And then as the earth began to warm, the Ice melted, the Ocean waters rose and they had to use other modes of transportation. So in about 600 years, there will be very little dry land maybe if any at all left. It is just the course of a Seven Thousand year Plan.
Then the earth will rest for a thousand years. Then creation will start all over again, but this time things will be different.
I think that the translation that the earth would be layed to rest by fire, really just meant that the earth would just get really, really, warmer and warmer. And some day it would be covered with water like it was in the very beginning.