Western Antarctic Ice Chunk Collapses

WASHINGTON — A chunk of Antarctic ice about seven times the size of Manhattan suddenly collapsed, putting an even greater portion of glacial ice at risk, scientists said Tuesday.

Satellite images show the runaway disintegration of a 160-square-mile chunk in western Antarctica, which started Feb. 28. It was the edge of the Wilkins ice shelf and has been there for hundreds, maybe 1,500 years.

This is the result of global warming, said British Antarctic Survey scientist David Vaughan.

Because scientists noticed satellite images within hours, they diverted satellite cameras and even flew an airplane over the ongoing collapse for rare pictures and video.

"It's an event we don't get to see very often," said Ted Scambos, lead scientist at the National Snow and Ice Data Center in Boulder, Colo. "The cracks fill with water and slice off and topple... That gets to be a runaway situation."

While icebergs naturally break away from the mainland, collapses like this are unusual but are happening more frequently in recent decades, Vaughan said. The collapse is similar to what happens to hardened glass when it is smashed with a hammer, he said.

The rest of the Wilkins ice shelf, which is about the size of Connecticut, is holding on by a narrow beam of thin ice. Scientists worry that it too may collapse. Larger, more dramatic ice collapses occurred in 2002 and 1995.

Vaughan had predicted the Wilkins shelf would collapse about 15 years from now. The part that recently gave way makes up about 4 percent of the overall shelf, but it's an important part that can trigger further collapse.

There's still a chance the rest of the ice shelf will survive until next year because this is the end of the Antarctic summer and colder weather is setting in, Vaughan said.

Scientists said they are not concerned about a rise in sea level from the latest event, but say it's a sign of worsening global warming.

Such occurrences are "more indicative of a tipping point or trigger in the climate system," said Sarah Das, a scientist at the Woods Hole Oceanographic Institute.

"These are things that are not re-forming," Das said. "So once they're gone, they're gone."

Climate in Antarctica is complicated and more isolated from the rest of the world.

Much of the continent is not warming and some parts are even cooling, Vaughan said. However, the western peninsula, which includes the Wilkins ice shelf, juts out into the ocean and is warming. This is the part of the continent where scientists are most concern about ice-melt triggering sea level rise.

___

On the Net:

The National Snow and Ice Data Center: http://nsidc.org

The British Antarctic Survey: http://www.bas.ac.uk/

Comments

[realpolitic]

01:44 PM on 03/30/2008

3)Anarctica

Why Antarctica's glaciers are shrinking remains an open question. What is certain is that the surface waters around Antarctica are getting warmer -- but it is not clear why that is happening. It could be, for example, that an increase in the upward circulation of the so-called circumpolar deep water, which is up to 1.5 degrees Celsius warmer than the rest of the water, is responsible for the melting of glaciers. Alternatively, the melting could even be due to direct heating of the water as a result of climate change. Snowfalls, the emergence of meltwater pools and volcanic activity could also play important roles.

http://climateark.org/shared/reader/welcome.aspx?linkid=94260&keybold=Antarctic%20glaciers%20melt

Even so, most experts said it is still impossible to model how the ice will react. Antarctica may accumulate more ice this century because of warming, blamed by the IPCC mainly on human use of fossil fuels, rather than slide faster into the sea.

Among worrying scenarios is the chance Antarctica will slide faster into the sea, perhaps if a ring of sea ice melts away in warmer oceans. Or melt water might flow under the ice sheets of Antarctica and Greenland, and act a lubricant to speed a slide.

http://climateark.org/shared/reader/welcome.aspx?linkid=92214&keybold=Antarctic%20glaciers%20melt

[realpolitic]

01:43 PM on 03/30/2008

2) Anarctica
New research confirms that ice sheets in West Antarctica are thinning at a far faster rate than in past millennia. Although scientists are divided as to the cause of the melt, many feel it is directly related to climate change.

Just what is behind the meltdown, however, is not entirely clear. Whereas it is not difficult to pinpoint global warming caused by human activity for increasing temperatures in the Arctic, the southern end of the planet is more difficult. The western side of the continent is thawing out wherever one looks, but on the eastern side, not much is happening

Johnson and her colleagues analyzed minerals from the Smith, Pope and Pine Island glaciers in four locations. In a paper in the March edition of the prestigious journal Geology, the researchers write that the data, for the first time, places the current massive loss of the West Antarctic ice sheet in the context of past millennia. And they confirm what scientists have long feared: The glaciers are losing their mass at an "unusually rapid" rate.

[realpolitic]

01:40 PM on 03/30/2008

Anarctica

Anarctica is separted by a mountain range dividing east and west. "Most of east Antarctica has been stable in a deep freeze with little sign of melt linked to global warming. Temperatures in west Antarctica, however, have been rising." In fact, temperatures in west Anarctica are rising faster than anywhere seen on the planet.(http://climateark.org/shared/reader/welcome.aspx?linkid=91712&keybold=Antarctic%20glaciers%20melt)

The region of greatest concern is West Antarctica, which includes the peninsula. Using satellites, scientists have been tracking snowfall, ice loss, and changes in the region's gravity field to gauge the amount of mass the continent's two large ice sheets are gaining or losing. The West Antarctic Ice Sheet is separated from its eastern sibling by a long chain of mountains, so gains or no change in mass for the continent as a whole may still mask significant changes on the West Antarctic Ice Sheet.

Recent studies have added to growing body of evidence that key glaciers flowing from the West Antarctic Ice Sheet are thinning at rates not seen since last ice age. For instance, for the past 4,700 years, Pine Island Glacier has thinned at a rate of 1-1/2 inches a year, according to a team of scientists from Germany. That rate is similar to those of other major glaciers in the region. But between 1992 and 1996, Pine Island Glacier thinned at an average rate of 63 inches a year.

http://climateark.org/shared/reader/welcome.aspx?linkid=95833&keybold=Antarctic%20glaciers%20melt

[realpolitic]

12:41 PM on 03/30/2008

3)
Many climbers are seeing the mountop snow disappear. "Mountaineers are bringing back firsthand accounts of vanishing glaciers, melting ice routes, crumbling rock formations and flood-prone lakes where glaciers once rose.

The observations are transforming a growing number of alpine and ice climbers, some of whom have scientific training, into eyewitnesses of global warming.

Chouinard pointed to recent trips where the ice had all but disappeared on the famous Diamond Couloir of 16,897-foot Mount Kenya, and snow was absent at low elevations on 4,409-foot Ben Nevis, Britain's highest peak, in the Highlands of northwest Scotland.

Already, Switzerland's Matterhorn had to be closed to some climbing at times because of recent summer rockfall attributed to global warming and its Great Aletsch Glacier—Europe's largest—has retreated a couple miles from its peak of 14 miles in length in 1860. The Swiss Alps' icy soil that glues its rock faces together is thawing, causing instability.

At Montana's Glacier National Park, glaciers are vanishing. In South America, great ice fields of Patagonia in Argentina and Chile are shrinking; Bolivia hopes to keep its only ski area open by using artificial snow as the Chacaltaya Glacier fades.

The glacier from which Edmund Hillary made his first ascent of 29,035-foot Mount Everest in 1953 has retreated so much that mountaineers now walk hours longer to reach it. A mile-long lake replaced the glacier at 20,305-foot Island Peak in Nepal's Everest region.

http://travel.msn.com/Guides/greenarticle.aspx?cp-documentid=385856

[realpolitic]

12:29 PM on 03/30/2008

4)

In fact, according to a Fox News summary of a 2006 Journal of Climate study:

The new global climate model simulated snow cover on the world's mountain ranges from 1977 to 2100 and found that by the end of this century, mountains in Europe and the U.S. will lose nearly half of their snow-bound water.

The Andes in South America will suffer a similar fate and snow-capped peaks in New Zealand will vanish completely, the model predicts.

Hardest hit will be mountains in temperate zones, where temperatures remain below freezing only at increasingly higher elevations, said Steven J. Ghan, staff scientist at the Department of Energy's Pacific Northwest National Laboratory.

http://www.foxnews.com/story/0,2933,196231,00.html

conclusion.

[realpolitic]

12:27 PM on 03/30/2008

3)
In fact, mountaineers, all over the world are bringing back first hand account of vanishing glaciers, melting ice routes, crumbling rock formations, and flood prone lakes where glaciers once rose. Already, Switzerland's Matterhorn had to be closed to some climbing at times because of recent summer rockfall attributed to global warming and its Great Aletsch Glacier—Europe's largest—has retreated a couple miles from its peak of 14 miles in length in 1860. The Swiss Alps' icy soil that glues its rock faces together is thawing, causing instability.

The glacier from which Edmund Hillary and Tenzing Norgay made their first ascent of 29,035-foot Mount Everest in 1953 has retreated so much that mountaineers now walk hours longer to reach it. A mile-long lake replaced the glacier at 20,305-foot Island Peak in Nepal's Everest region.

http://travel.msn.com/Guides/greenarticle.aspx?cp-documentid=385856

No question that the small glaciers and ice caps are melting. "More than half of the estimated 650 billion tons of ice lost to the oceans annually comes from the discharge of small glaciers and icecaps, said Professor Tad Pfeffer of CU-Boulder's Institute of Arctic and Alpine Research. Such ice masses are estimated to be shedding 400 billion tons of ice -- nearly equal to the volume of Lake Erie -- compared to the Greenland and Antarctic ice sheets, which combined are estimated to be contributing about 250 billion tons annually, according to the analysis.

http://www.sciencedaily.com/releases/2007/07/070719143502.htm

(cont.)

[realpolitic]

12:23 PM on 03/30/2008

2)
Such midlevel glaciers are an important sorce of fresh water supply in the summer for many people. "Since 1980 the World Glacier Monitoring Service has kept a constant record of net gain or loss in mass balance of 30 reference glaciers from nine mountain ranges around the world.

In North America, Dr Bruce Molina of the US Geological Survey says that in Alaska '99-plus per cent of glaciers are retreating or stagnating'.

In the European Alps, a report last year by UNEP said glaciers declined, from a peak in the 1850s, by 35 per cent by 1970 and by 50 per cent by 2000, and lost 5-10 per cent in the mega-hot year of 2003 alone.

UNEP has also reported declines in the last 50-150 years of 1.3 per cent in the Arctic islands to 50 per cent in the North Caucasus in Russia, 25-50 per cent in central Asia, a 2km retreat of the massive Gangotri glacier which feeds the Ganges, 49 to 61 per cent in New Zealand, and 80 per cent in the high mountains of southern Africa.

Based on the forecast increase in global temperatures this century, UNEP report warned of 'deglaciation of large parts of many mountain regions in the coming decades'. Perhaps most shockingly, it predicted two-thirds of China's glaciers would disappear by 2050, and 'almost all would be gone by 2100.'"

http://www.guardian.co.uk/environment/2008/mar/16/glaciers.climatechange

(cont.)

[realpolitic]

12:13 PM on 03/30/2008

Regarding the mountaintop ice, the studies of Kilimanjaro are unique to Kilimanjaro because the atitude at the summit is such that temperatures are subfreezing all year. "Unlike midaltitude glaciers which are warmed and melted by surrounding air in summer, ice loss on Kilimanjaro is strictly driven by solar radiation." (No distinction is made between midaltitude glaciers on mountains and the snow caps.)
http://www.sciencedaily.com/releases/2007/06/070611153942.htm

But, I think the point is still unclear. "Forest reduction in the areas surrounding Kilimanjaro, and not global warming, might be the strongest human influence on glacial recession. Loss of foliage causes less moisture to be pumped into the atmosphere, leading to reduced cloud cover and precipitation and increased solar radiation and glacial evaporation. ..."

However, "global warming began to take effect in East Africa by the early 20th century."

"The warming increases humidity, and as the air gets more moist, it hinders evaporation," Hastenrath explained. "The energy saved from evaporation is instead spent on melting. That might seem good —to stop evaporation of the glaciers—but it's certainly not. Melting is eight times more energy-efficient than evaporation, so now, with global warming, glaciers are disappearing eight times faster than before."

http://news.nationalgeographic.com/news/2003/09/0923_030923_kilimanjaroglaciers_2.html

So perhaps there is less precipitation, but still more humidity due to global warming that hinders evaporation that may be partially causing the snows of Kilimanjaro to melt..

(cont.)

[realpolitic]

10:56 PM on 03/27/2008

Loss of Ice Leaves Experts Stunned
By David Adam Envoronmental Correspondent
Guardian.co.uk

The Arctic ice cap has collapsed at an unprecedented rate this summer and levels of sea ice in the region now stand at record lows, scientists have announced.

Experts say they are "stunned" by the loss of ice, with an area almost twice as big as the UK disappearing in the last week alone.

So much ice has melted this summer that the Northwest passage across the top of Canada is fully navigable, and observers say the Northeast passage along Russia's Arctic coast could open later this month.

If the increased rate of melting continues, the summertime Arctic could be totally free of ice by 2030.

Mark Serreze, an Arctic specialist at the US National Snow and Ice Data Centre at Colorado University in Denver, said: "It's amazing. It's simply fallen off a cliff and we're still losing ice."

The Arctic has now lost about a third of its ice since satellite measurements began thirty years ago, and the rate of loss has accelerated sharply since 2002.

http://www.guardian.co.uk/environment/2007/sep/04/climatechange

[Kula]

08:59 PM on 03/26/2008

Global warming causes everything. Read this. It's lunacy!!!!

http://americanthinker.com/blog/2007/11/everything_is_caused_by_global.html

[realpolitic]

09:17 PM on 03/27/2008

Your cite should be called "American Non-Thinker."

[Bluedog12]

08:19 PM on 03/26/2008

I have extra winter coats and a big rowboat to get me through this Global warming MSM hoax. When this hoax passes I'll put my boat away or maybe I'll row to my friend Rush's house in Cape Giredau. I just hope I don't hit that dam hoax iceberg. I'll bring my celine dion CD just incase.

[LibsRway2funny]

07:47 PM on 03/26/2008

Let’s put this in perspective.

The account may be misinterpreted by some as the ice cap or a significant (vast) portion is collapsing. In reality it and all the former shelves that collapsed are small and most near the Antarctic peninsula which sticks well out from Antarctica into the currents and winds of the South Atlantic and lies in a tectonically active region with surface and subsurface active volcanic activity. The vast continent has actually cooled since 1979.

http://wattsupwiththat.wordpress.com/2008/01/22/surprise-theres-an-active-volcano-under-antarctic-ice/

[kingcityguru]

07:42 PM on 03/26/2008

Since deep water sensors actually show that temperatures in the world's oceans have actually DECREASED steadily over the last 8 years, maybe the ice broke off because 1) it is normal; 2) it was so cold it cracked off; 3) who knows.

By the way, this has been the coldest winter in a half century.

[kujo76]

05:02 PM on 03/26/2008

Where it looks like sea ice extent has increased 44% in the antarctic since 1980, the sea ice extent in arctic has decreased by only .066%. Overall, polar ice extent has grown 1.1 million square kilometers in the polar regions since 1980. Why is this happening if polar temperatures are getting warmer? Is there a scientist in the house?

http://nsidc.org/cgi-bin/wist/wist.pl?wcf=seaice_index

[kujo76]

04:50 PM on 03/26/2008

This just in... 6 months ago: At the end of last winter in the southern hemisphere, there was more ice there than had ever been recorded. Sea ice extent is at a record high in Antarctica.

http://nsidc.org/cgi-bin/wist/wist.pl?wcf=seaice_index

Can someone explain how Global Warming has caused the formation of all of this ice in Antarctica? I'm awaiting a reply from the NSIDC.