Posted on 12/12/2006 8:13:39 AM PST by cogitator
The worrying shrinkage of Arctic sea ice could accelerate dramatically in coming decades, leaving the planet's most northerly ocean virtually devoid of ice in summer by 2040, according to a study published on Tuesday.
The paper, which appeared in the US journal Geophysical Research Letters, mainly points the finger at greenhouse-gas emissions.
It warned that if carbon pollution continues to increase at present rates, the Arctic's normal cycle of freezing and thawing faces catastrophic disruption.
A simulation run by scientists at the National Center for Atmospheric Research (NCAR) and Canada's McGill University predicted that the area covered by ice in September -- before new ice begins to form each year -- could shrink from about 5.9 million square kilometres to 1.9 million sq. kms. (2.3 million to 770,000 sq. miles) within a decade.
By 2040, "only a small amount of perennial sea ice" would remain along the north coasts of Greenland and Canada in summer, NCAR said in a press release.
In winter, ice thickness would be reduced from about 3.5 metres (about 12 feet) to less than a metre (three feet).
"We have already witnessed major losses in sea ice, but our research suggests that the decrease over the next few decades could be far more dramatic than anything that has happened so far," said NCAR scientist and lead author of the study, Marika Holland.
Greenhouse gases trap the Sun's heat, gradually forcing up Earth's surface temperature.
But several peripheral factors could also account for such a rapid meltdown.
Open water absorbs more sunlight than ice, accelerating the rate of warming and leading to more ice loss. In addition, global climate change is likely to drive warmer ocean currents into the Arctic region.
"This is a positive feedback loop with dramatic implications for the entire Arctic region," Holland said.
The shrinkage of the Arctic ice cap is viewed with alarm by scientists, as it appears to perturb important ocean currents elsewhere, notably the Gulf Stream, which gives western Europe its balmy climate.
It also threatens animals such as polar bears and seals that depend on ice -- as well as Inuits and other native peoples who hunt these animals and have to travel on thinner ice in this quest.
There are geopolitical implications, too, as Canada, Russia and the United States jockey to claim rights over transpolar passages that open up within their newly ice-free waters.
In September, European scientists unveiled satellite images from late August showing that perennial sea ice -- thick ice that is normally present year-round and is not affected by the Arctic summer -- had disappeared over an area bigger than the British Isles.
The study released Tuesday concludes that reduced rates of greenhouse gas emissions could slow the ice loss. "Our research indicates that society can still minimize the impacts on Artic ice," Holland said.
Looks like a good, but long, read. Bookmarking for later...
Not a good thing if permafrost melts. Structures cannot
prevail in marshes.
Again you misquote him. Just what the hell is wrong with quoting somebody accurately?
2. Additional cause is massive emissions of soot from Chinese coal fired power stations that condenses on arctic ice causing increased absorbtion of sun energy and thus melting gthe ice.
3. Not to worry as the melting fresh water will turn off the gulf stream thas starting anoter 400 yera "mini" ice age in N. Europe that should polease trhe global warmers.
So according to your linked site, no consensus. Increased interior ice, and decreased perimeter ice.
Using more recent data:
The critical point for Greenland is whether the increased rate of glacier motion more than compensates for the greater accumulation on the surface. While the broad picture of what is happening is consistent between these papers, the bottom-line value for Greenland's mass balance is different in all three cases. Looking just at the dynamical changes observed by Rignot & Kanagaratnam, there is an increased discharge of about 0.28 mm/year SLE from 1996 to 2005, well outside the range of error bars. This is substantially more than the opposing changes in accumulation estimated by Johannessen et al and Zwally et al, and is unlikely to have been included in their assessments. Thus, the probability is that Greenland has been losing ice in the last decade. We should be careful to point out though that this is only for one decade, and doesn't prove anything about the longer term. As many of the studies make clear, there is a significant degree of interannual variability (related to the North Atlantic Oscillation, or the response to the cooling associated with Mt. Pinatubo) such that discerning longer term trends is hard.
http://www.realclimate.org/index.php/archives/2006/03/greenland-ice-and-other-glaciers/
Again, it looks like no consensus of loss or gain.
What is the temperature trend from 1998 to 2006?
"The spatially averaged increase is 5.4 cm per year over the study area, when corrected for post-Ice Age uplift of the bedrock beneath the ice sheet. These results are remarkable because they are in contrast to previous scientific findings of balance in Greenland's high-elevation ice."
A net increase in mass.
Yup, those NEOs.
....the ones that go "bump" in the night, are the ones that'll get us....
C'mon, I was off by just two decimal point(s). :D
http://youtube.com/watch?v=9JSR_6qfXTg
http://www.youtube.com/watch?v=Loc8bpczZPY
The trend below 1500 metres however does not include the steeply-sloping marginal areas where current altimeter data are unusable.
This might mean that the loss of 2cm/yr in the below 1500 meters areas the satellite can measure, along with the marginal areas, roughly balances the 6.0cm/yr gain in the interior (above 1500 meters).
Hence the article's "no consensus" and "need for further data". Or in the words of the study's author:
"There is clearly a need for continued monitoring using new satellite altimeters and other observations, together with numerical models to calculate the Greenland Ice Sheet mass budget," Johannessen added.
The one thing we know for sure is that Mother Earth never remains in stasis. If she slows down the bears gonna catch her.
I think you'll find it quite interesting. Here's some info on Crichton's credentials:
Bio: CRICHTON, (John) Michael. American. Born in Chicago, Illinois, October 23, 1942. Educated at Harvard University, Cambridge, Massachusetts, A.B. (summa cum laude) 1964 (Phi Beta Kappa). Henry Russell Shaw Travelling Fellow, 1964-65. Visiting Lecturer in Anthropology at Cambridge University, England, 1965. Graduated Harvard Medical School, M.D. 1969; post-doctoral fellow at the Salk Institute for Biological Sciences, La Jolla, California 1969-1970. Visiting Writer, Massachusetts Institute of Technology, 1988.
Thanks for the cut and paste ping pong:) I learned something.
I can piss off either side now.
LOL, you bet!
No they are not and this is irrelevant to the argument at hand.
Actually, clouds are the most effective of the greenhouse gases. If you want a warm winter night or a really mugged unbearable summer night, there is nothing like cloud cover to do the trick.
I would not go around calling people morons unless you are sure you know what you are talking about.
Global warming is NOT a hoax. It's real.Where's your proof?
Just because 'station records' near urban areas show warming DOES NOT mean so-called 'global;' warming is occurring ...
Foor instance, balloon and Microwave Sounding Units do not indicate this 'global' phenom.
Global warming is a fact,See my previuous post; you, too, have been taken in and have failed to do your homework.
Water vapor is indeed the most effective and most active greenhouse agent by far.
Clouds OTOH, operate to counteract conversion of visible spectum into heat at the surface by reflecting radiant energy back towards space.
Low cloud layers induce net cooling as both daytime solar radiation and atmospheric heat in the form of IR above clouds, are reflected upward to space.
A consequence of that reflectivity is that night time losses in the heat balance are not made up in the daytime influx of solar energy interacting at the surface which would otherwise heat the greenhouse gas components in the atmosphere.
High altitude ice clouds also act as a very efficient reflector of visible solar spectrum again inducing net cooling at the surface by intercepting incoming solar energy that sets thermal equilibrium of the atmosphere.
Cloud interactions are very complex and poorly accounted for in current climate models. Therein lay the weakest links in the Global Warming rationale.
I agree we do have Global WarmingProvide/cite your 'proof'; avoid the use of data from those weather recording stations which have seen urban encroachment, have failed to have the trees and bushes in the vicinity maintained and trimmed back SUCH THAT the recording/measurement structure has an un-obstructed view of the open sky ...
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