Posted on 09/23/2003 5:56:43 AM PDT by pa_dweller
The largest ice shelf in the Arctic has fractured, releasing all the water from the freshwater lake it dammed.
The Ward Hunt Ice Shelf is located on the north coast of Ellesmere Island in Canada's Nunavut territory.
The huge mass of floating ice, which has been in place for at least 3,000 years, is now in two major pieces.
The scientists who report the break-up in the journal Geophysical Research Letters (GRL) say it is further evidence of ongoing and accelerated climate change in the north polar region.
The researchers - Warwick Vincent and Derek Mueller of Laval University in Quebec City, Canada; and Martin Jeffries of the University of Alaska Fairbanks, US - have been studying the shelf onsite and through satellite radar imagery and helicopter overflights.
Lost water
They say the fracturing - which has been developing since the spring of 2000 - is the end result of a three-decade-long decline.
"We're now seeing some very extensive fractures in it that extend many kilometres horizontally across the ice-shelf; and they extend all the way through from the top to the bottom, many tens of metres through the ice shelf. And we've never seen fractures like this," Dr Jeffries told the BBC.
They warn that major free-floating ice islands could pose a danger to shipping and to drilling platforms in the Beaufort Sea.
The immediate consequence of the rupture has been the loss of almost all of the freshwater from the Northern Hemisphere's largest epishelf lake (a body of mostly freshwater trapped behind an ice shelf).
The freshwater lay in the 30-kilometre- [20-mile] long Disraeli Fiord.
At its deepest, the freshwater measured 43 metres [140 feet], and sat atop 360 metres [1,200 feet] of denser ocean water.
Other worlds
The loss of fresh and brackish water has changed the environment for the microscopic animals and algae living in the area.
"These are very rare and unusual ecosystems and they have been studied as possible analogues for life on a colder Earth and life on the planets," Dr Jeffries said.
"And if we are losing them, we are losing the opportunity to study life earlier in Earth history and elsewhere in the Solar System."
Scientists monitor continuously ice-shelf development in both the Arctic and the Antarctic.
In the southern polar region, recent times have witnessed some dramatic changes.
Last year, the 3,250-square-km Larsen B Ice Shelf on the Antarctic Peninsula shattered over a period of a month into thousands of icebergs.
The peninsula is one of the three fastest-warming regions on Earth - temperatures have gone up 2.5 degrees in 50 years.
Global change
Mueller, Vincent, and Jeffries say their calculations suggest changes of a similar nature have been taking place in the Ellesmere Island area.
A century ago, the entire northern coast of the island was reported to be fringed with a continuous ice shelf. About 90% of that ice area had been lost by 1982, the scientists say.
The precise timing of the break-up of the remnant Ward Hunt Ice Shelf may have been influenced by freeze-thaw cycles, wind, and tides, they tell GRL.
Other factors may include changes in Arctic Ocean temperature, salinity, and flow patterns, they add.
"Computer models show quite convincingly that global climate change would be manifested first and amplified in the polar regions and in particular in the Arctic," Dr Jeffries said
"Our observations at Ward Hunt Ice Shelf fit in with a broader picture of Arctic change which fits in with our understanding of how the Arctic climate would respond to global change."
I think the scientific evidence shows that the world is getting warmer. I don't think that the evidence shows that this increase was caused by man. In the middle ages, there was a mini-ice age which was not man made. We overestimate our impact on the planet.
I heard they also eat babies and enjoy killing kittens!
Only Dean can save us now!!!
(LOL)
It's already BROKEN, too late. Move along, nothing to see here.
It has ALWAYS BEEN "too late to do anything" about natural changes in climate. As a friend of mine put it "Mother Nature don't care!".
ALL (and I do mean ALL) of the scientific information indicates that the current global warming "is" a natural process, governed by cyclic changes in the luminosity of the sun, and oscillating changes in the cycles of the earth's orbit. Said process started thousands of years ago and is on-going today.
The evidence of any significant human-induced contribution to global warming is nil.
What precisly could we do about natural changes in the Earth's climate and assuming man is responsible what can we actually do to revert the process ?
I think the scientific evidence shows that the world is getting warmer.
Not exactly, depends on one's time frame.
Ice Ages & Astronomical Causes Origin of the 100 kyr Glacial Cycle Figure 1-1 Global warming Figure 1-2 Climate of the last 2400 years
Figure 1-3 Climate of the last 12,000 years Figure 1-4 Climate of the last 100,000 years Figure 1-5 Climate for the last 420 kyr, from Vostok ice |
I don't think that the evidence shows that this increase was caused by man. In the middle ages, there was a mini-ice age which was not man made. We overestimate our impact on the planet.
Enviro-political groups media do anyway:
Mankind's impact is only 0.28% of Total Greenhouse effect
" There is no dispute at all about the fact that even if punctiliously observed, (the Kyoto Protocol) would have an imperceptible effect on future temperatures -- one-twentieth of a degree by 2050. "
Dr. S. Fred Singer, atmospheric physicist
Professor Emeritus of Environmental Sciences at the University of Virginia,
and former director of the US Weather Satellite Service;
in a Sept. 10, 2001 Letter to Editor, Wall Street Journal
Anthropogenic (man-made) Contribution to the "Greenhouse
Effect," expressed as % of Total (water vapor INCLUDED)
Based on concentrations (ppb) adjusted for heat retention characteristics % of All Greenhouse Gases % Natural
% Man-made
Water vapor 95.000% 94.999%
0.001% Carbon Dioxide (CO2) 3.618% 3.502%
0.117% Methane (CH4) 0.360% 0.294%
0.066% Nitrous Oxide (N2O) 0.950% 0.903%
0.047% Misc. gases ( CFC's, etc.) 0.072% 0.025%
0.047% Total 100.00% 99.72
0.28%
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