Hundreds of Antarctic Peninsula Glaciers Accelerating as Climate Warms; UN Issues Global Ice and Snow Report
06 June 2007
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| Rates of surface-elevation change in Antarctica based on radar-altimeter data (black), mass-budget calculations (red), and satellite gravity measurements (blue). Rectangles depict the time periods of observations (horizontal) and the upper and lower estimates of mass balance (vertical).Click to enlarge. Source: UNEP Global Outlook for Ice and Snow |
Hundreds of glaciers on the Antarctic Peninsula (AP) are flowing faster, further adding to sea level rise according to new research published this week in the Journal of Geophysical Research. Climate warming, which is already causing increased summer snow melt and ice shelf retreat of the Antarctic Peninsula, is the most likely cause.
Using radar images acquired by European ERS-1 and -2 satellites, scientists from British Antarctic Survey (BAS) tracked the flow rate of more than 300 previously unstudied glaciers. They found a 12% increase in glacier speed from 1993 to 2003. These observations, echoing recent findings from coastal Greenland, indicate that the cause is the melting of the lower glaciers, which flow directly into the sea.
As the lower glaciers thin, the buoyancy of the ice can lift the glaciers off their rock beds, allowing them to slide faster.
We attribute this widespread acceleration trend not to meltwater-enhanced lubrication or increased snowfall but to a dynamic response to frontal thinning. We estimate that as a result, the annual sea level contribution from this region has increased by 0.047 ± 0.011 mm between 1993 and 2003. This contribution, together with previous studies that assessed increased runoff from the area and acceleration of glaciers resulting from the removal of ice shelves, implies a combined AP contribution of 0.16 ± 0.06 mm yr-1. This is comparable to the contribution from Alaskan glaciers, and combined with estimated mass loss from West Antarctica, is probably large enough to outweigh mass gains in East Antarctica and to make the total Antarctic sea level contribution positive.
In February this year, the United Nations Intergovernmental Panel on Climate Change (IPCC) reported that they could not provide an upper limit on the rate of sea-level rise from Antarctica in coming centuries because of a lack of understanding of the behaviour of the large ice sheets.
These new results give scientists a clearer picture about the way that climate warming can affect glaciers both in the Arctic and Antarctic. Furthermore, they pave the way for more reliable projections of future sea level rise, and provide a better basis for policy decisions.
The Antarctic Peninsula has experienced some of the fastest warming on Earth, nearly 3°C over the last half-century. Eighty-seven percent of its glaciers have been retreating during this period and now we see these glaciers are also speeding up. It’s important that we use tools such as satellite technology that allow us to monitor changes in remote and inaccessible glaciers on a regional scale. Understanding what’s happening now gives us our best chance of predicting what’s likely to happen in the future.
—Dr Hamish Pritchard, Lead Author
Separately, the UN Environment Program released a comprehensive new report—The Global Outlook for Ice and Snow—showing that the amount of ice and snow, especially in the Northern Hemisphere, has decreased substantially over the last few decades, mainly due to human-made global warming.
The declines in snow cover, sea ice, glaciers, permafrost and lake ice will affect hundreds of millions of people, according to the report, with impacts including significant changes in the availability of water supplies for drinking and agriculture, rising sea levels affecting low lying coasts and islands and an increase in hazards such as subsidence of currently frozen land.
The report covers all parts of the cryosphere (the world of ice): snow, land ice, sea ice, river and lake ice, and frozen ground. More than 70 scientists from around the world contributed to The Global Outlook for Ice and Snow, which was compiled in part to support the International Polar Year (IPY) running from 2007 to 2008.
The peer-reviewed report builds on and in some areas extends the work of the Intergovernmental Panel on Climate Change (IPCC) whose fourth assessment reports were issued between February and May this year.
The report also flags up areas in need of further scientific clarity which the IPY, a major international science initiative of the World Meteorological Organization and the International Council for Science of which UNEP is a partner, aims to resolve.
These include the likely fate of the Antarctica and Greenland ice sheets where 98 to 99% of the world’s freshwater ice on the Earth’s surface is held. Even just a 20% melting of Greenland and a 5% melting of Antarctica would result in a four to five meter sea level rise.
Resources:
“Widespread acceleration of tidewater glaciers on the Antarctic Peninsula” H. D. Pritchard and D. G. Vaughan; Journal of Geophysical Research, Vol. 112, F03S29, doi:10.1029/2006JF000597, 2007
Wait, I thought all those "in the know" deniers were saying that snow and ice were increasing in the Antarctic? Hmmm...?
Posted by: Shlomo | 06 June 2007 at 08:35 AM
" "probably" large enough to outweigh mass gains in East Antarctica and to make the total Antarctic sea level contribution positive."
there are a lot of voices out there about global surface temp - it's all a bunch of confusion to me.
Posted by: Rick | 06 June 2007 at 09:03 AM
The satellite data still says that. I'm intrigued by there "previously unstudied" glaciers are found to be "accelerating". From what unstudied baseline, do they determine this?. More pablum for the gullible.
I will reserve from smirking when nouveau-religious cranks start finding in a few years that the revealed merely pseudo-scientific claptrap that you've been fed, is all wrong. Just like the "Global Cooling", "Dying Oceans" by 1975, and Malthusian human population crash, pseudo-scientific claptrap was proven wrong.
It was not that long ago this happened to you, from the '70s clothed in the aura of "Science" as published by non-Scientific political hacks, for gullible non-scientists.
this Scientist will continue to measure reports through the filter of Science trained mind, and proper scientific caution and reservation.
I will give you a little dose of cheap insight nonetheless, there is an enormous inertia in the billions of cubic miles of ICE that took millions of years to deposit; it will take a similar amount of time to dissipate in Antarctica. Check back if it continues until 3107 AD, or 4107 AD, and I might start to become concerned.
In Greenland, it is true that there is less Ice than at the end of the Little Ice Age in the 18th century, but still lots more than in 1000 AD at the beginning of the Medieval Warm Period. Advancing and retreating glaciers are a NORMAL phenomenon.
Posted by: Stan Peterson | 06 June 2007 at 10:04 AM
Stan: Sometimes it's prudent to head a warning even if there's only a chance they are right. Isn't it better safe than sorry? Besides, if a little worry about global warming helps to push us off of petroleum and onto something cleaner (like electricity), I'm perfectly willing to make like chicken little to get some people moving. Sooooo ... Global Warming! Peak Oil! Terrorists! Bankruptcy! Balance of Payments! Commie Liberal Leftist Subversives! Pat Robertson! Peak Beer! Whatever!
Posted by: Neil | 06 June 2007 at 10:28 AM
LOL ... heed ... not head
Posted by: Neil | 06 June 2007 at 10:29 AM
Peak Beer!
Now you've got my attention!
Posted by: Matthew | 06 June 2007 at 10:53 AM
The arrogance of some deniers, and you in particular Stan, is breathtaking. If you bothered to read the article and follow through one of the links you'll see that the study compares glacier flows between 1992 and 2005 and the 12% refers to an acceleration in flow rates between 1993 and 2003.
Posted by: Scatter | 06 June 2007 at 12:04 PM
Here a way to deal with that pesky satellites data.
U.S. cutting back efforts to monitor global warming from space
Posted by: DS | 06 June 2007 at 01:44 PM
Scatter you Dolt,
So you're afraid of a little melt water will cause the end of world as we know it? You read about a data set that’s only 10 years and you’re wetting yourself, but then you attack those who question the data. Oh Yes, the Marxists who run the UN don’t have an agenda now do they? It’s the blind, following the blind! OMG – LOL
Posted by: GeoLopez | 06 June 2007 at 03:53 PM
Poor Stan and Geo - callouses on their knuckles.
Posted by: philip | 06 June 2007 at 05:02 PM
Faster glacier flow is more an indication of ice building up in the interior than it is of warming.
Ice builds and its weight pushes the glacier downhill. Think of an avalanche in slow motion because ice doesn't flow as easily as snow. There is no mystery here and no paradox between ice buildup -- as proven by the so-called "deniers" -- and more calving at the shoreline. The ice isn't calving because of warming, it's calving because it has nothing under it to support the growing weight of ice once it is pushed off the land.
If it weren't for this mechanism, ice would just build up forever on Antartica, until there was no free water left on the planet.
Posted by: Kirk Ellis | 06 June 2007 at 06:34 PM
man, whether the antartic glaciers are accelerating or not doesnt meant anything if "world" (superpower)leaders already thinks we are heading to a deep sh*t future, with dwindling natural resources as one of their main agenda
by their actions To Date, theyre already shaping up our future
"a radiated earth"
maybe glaciers would increase after all, nuclear winter style
Posted by: ditto | 06 June 2007 at 07:26 PM
Antarctic ice sheet is dynamic system, and fluctuate naturally in quite wide margins. And it is extremely complicated to measure ice mass balance. I can summarrise what I’ve learned for last couple of months from about dozen scientific articles.
Antarctic peninsula does warms dramatically and loose ice. However, it is very small piece of land and represents only 2-3% of Antarctic ice mass. Most scientists point to periodic changes in ocean currents and winds as main reason for ice melting.
West Antarctic ice sheet (about 1/3 of all Antarctic ice) is loosing some small amount of ice on periferia, but it is not yet conclusive.
Massive East Antarctic ice sheet, about 2/3 of Antarctic ice, is growing in volume, for some years quite fast – up to 10 centimeters, which accelerates ice flow to the ocean, so nicely depicted in price winning documentary. Increased precipitation is the driving factor of this increase. For Antarctica as a whole, amount of ice is increasing, compensating for slight lost of ice in coastal regions of Greenland.
Couple of articles investigated possibility of ice “slide” into ocean for both Antarctica and Greenland, and found it impossible. Main mass of Greenland ice sheet is situated in the landlocked bowl, and could not slide into ocean. About the same picture is true for Antarctica: surrounding ice sheets underwater sediment bars prevent ice from sliding or floating into the ocean.
Amount of sea ice is stable over last three decades:
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.anom.south.jpg
Ocean level continue its 10 000 years rise, last century with very small speed of 3-30 centimeters per century (different researches present different estimations), due to thermal expansion while Earth warms-up from Little Ice Age. Increasing Antarctic ice mass slightly offsets this rise.
It would be interesting to hear explanations of “scientists” from formerly Great Britain how Antropogenic Global Warming affects Antarctic ice, because Southern hemisphere is not warming at all, and according to both satellite measuring systems temperatures over South Polar region are cooling for all 30 years of measurements (contrary to all IPCC climate models predictions):
http://www.junkscience.com/MSU_Temps/UAHMSUSPol.html
http://www.junkscience.com/MSU_Temps/RSSSPol.html
Posted by: Andrey | 06 June 2007 at 08:31 PM
Junk science junk science junk science...
Please.
Posted by: anon | 06 June 2007 at 09:36 PM
No Geo I'm not wetting myself. In fact I'm very optimistic about our future assuming our leaders have the balls for it.
All I was doing is calling Stan on his arrogant attitude (I think I'm safe in assuming that neither he nor yourself are experts in the glaciology of the Antarctic Peninsula) and pointing out that because his filters are set to blinkered he didn't even bother to read what he was mouthing off about.
I would also add that the assumption that the world's scientists are deliberately misleading the world to further their communist agenda is paranoid in the extreme.
Posted by: Scatter | 07 June 2007 at 01:48 AM
"Billions of cubic miles of ICE" is off by a factor of about a thousand. If that is representative of your understanding then your conclusions are worthless. This is why the opinions of professionals who have studied the matter are given more weight than those of ideologues, the ignorant, etc. But thanks for sharing.
Posted by: richard schumacher | 07 June 2007 at 02:23 AM
erh
scatter, do you remember Al gore story about the geography teacher and the student thingy
was he refering to these blokes
(of course the teacher)
are they on Dub-ya scientist list? ponder ponder
Posted by: ditto | 07 June 2007 at 02:41 AM
This must be a result of someone installing some solar panels and increasing the albedo! :)
Posted by: darwin | 07 June 2007 at 08:08 AM
Andrey, according to the IPCC third assessment the sea averaged 1-2mm rise per year last century and 3mm/yr between 1993-2003. Antarctic temperatures have risen moderately over the last 150 years, around 0.2C since last century. (Schneider, D. P., E. J. Steig, T. D. van Ommen, D. A. Dixon, P. A. Mayewski, J. M. Jones, and C. M. Bitz (2006), Antarctic temperatures over the past two centuries from ice cores, Geophys. Res. Lett., 33, L16707, doi:10.1029/2006GL027057.)
Please reference your spiels.
Apart from always cherry picking data to fit your conclusions Andrey, here is another point you don't seem to understand about science and it is the same problem many creationists have. It is the assumption that if there is any small bit of data that doesn't seem to fit the current conception, this disproves it. In fact there are many instances in science when some piece of data doesn't exactly fit. However usually these inconsistencies are subsequently ironed out with better data. It is the hypothesis that is most consistent with the overall balance of data that is accepted at any particular time. Anthropogentic warming has been the hypothesis most in agreement with the data for decades now and its agreement keeps getting stronger. That's why the IPCC conclusions are more and more definite. So, if you are going to seriously dispute anthropogenic warming you are going to have to come up with an alternative hypothesis that is better supported.
Good luck.
Stan, keep it up, you are actually quite amusing.
Geo, you seem to be one of those many people who somehow swap science for politics. Since you don't like the imaginary politics, you reject the real science. Get over it.
Posted by: marcus | 07 June 2007 at 07:37 PM
Marcus:
I do not really getting your point. I am trying not to cherry pick, unlike promoters of AGW theory.
Your 1-2 mm per year sea level rise in 20 century is 10-20 centimeters per century, which is within 3-30 centimeters number I presented. I did not cherry-pick the smallest number, unlike IPCC which always cherry-picks the highest numbers. Also I did not mention that couple of researches found that sea level rise is slowing, because there are different estimations, some indicate increase, some decrease, but for short period of 10-20 years it is very doubtful it is possible to say with any certainty. This is the reason I did not say anything about it.
0.2 C Antarctic temperature per last century rise is interesting estimation, but seriously, how it is possible to estimate it with such precision for a continent without human population, with 3-5 quite resent (about 50 years) weather stations, etc.? I did not mention that these weather stations indicate same cooling trend for 50 years, because these measurements are inadequate for the task. The only means of assessing Antarctic temperature is satellite measurements, commenced in 1978, and these measurements indicate small cooling trend.
You have very strange ideas about science. It is burden of new theory to prove itself, not vise versa. And theory of AGW is way short of this goal. As a matter of fact, most scientific findings disprove the theory; IPCC simply distorts actual scientific data to justify its very existence (Intergovernmental Panel of CLIMATE CHANGE), and politically motivated media and burocracy/politicians do the rest to inflate it to ridiculous proportions. As an example, re-read discussed article and it presentation.
As for alternative hypotheses, your gotta be kidding. IPCC itself indicates that antropogenic GHG emissions began to influence global climate only 50 years ago. All previous warming is attributed to natural factors.
For real factor take a look at Wiki for PDO:
• 1905: After a strong swing, PDO changed to a "warm" phase.
• 1946: PDO changed to a "cool" phase.
• 1977: PDO changed to a "warm" phase.
• 1998: PDO index showed several years of "cool" values, but has not remained in that pattern.
PDO, being 30-years periodic phenomena, had TWO warm phases and ONE cool phase in 20 century, which explains most of 0.6 C warming over 20 century. Remaining warming trend of 0.1-0.2 C could be attributed to noise, solar magnetic fluctuations, or to antropogenic factors (most probably mix of these three), but in any case this minuscule number does not justifies “end of the world” and “act now” hysteria.
For recent and very real effects of PDO switching to cool phase take a look at dramatic cool weather events in South America (I do not even mention the weather on US/Canada West coast):
http://icecap.us/images/uploads/TheGreatSouthAmericanMayColdSpell.doc
Posted by: Andrey | 08 June 2007 at 11:34 AM
It sounds like more data is needed about the Antarctic. Overall, human-caused global warming seems to be supported by much more data than goes the other way. However, I and all others here should admit to not attending the in-depth conferences that geologists and other scientists actively in the field have the benefit of. It appears that the Antarctic situation is still controversial, and there is a variety of data that has not yet been reconciled. As some have said, that does not destroy the human-caused global warming hypothesis, but only provides something that we need to examine more closely until enough facts are gathered.
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