Scientists watch polar areas for changes

NF Reporter · 03-01-2007, 10:42 AM

AP - Are we really heading for an ice-free Arctic? More than 50,000 researchers hope to find an answer during a massive study of how global warming and other phenomena are changing the coldest parts of the Earth — and what that means for the rest of it.

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waltky · 08-21-2007, 01:57 AM

New islands appearing from melting ice...

Islands appear as Arctic ice melts
August 21, 2007 - PREVIOUSLY unknown islands are appearing as Arctic summer sea ice shrinks to record lows, raising questions about whether global warming is outpacing UN projections, experts say.

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Polar bears and seals have also suffered this year on the Norwegian archipelago of Svalbard because the sea ice they rely on for hunts melted far earlier than normal. "Reductions of snow and ice are happening at an alarming rate," Norwegian Environment Minister Helen Bjoernoy said at a seminar of 40 scientists and politicians that began yesterday in Ny Alesund, 1200km from the North Pole.

"This acceleration may be faster than predicted" by the UN climate panel this year, she said. Ny Alesund calls itself the world's most northerly permanent settlement, and is a base for Arctic research. The UN panel of 2500 scientists said in February that summer sea ice could almost vanish in the Arctic towards the end of this century. It said warming in the past 50 years was "very likely" the result of greenhouse gases caused by fossil fuel use.

"There may well be an ice-free Arctic by the middle of the century," Christopher Rapley, director of the British Antarctic Survey, told the seminar, accusing the UN's Intergovernmental Panel on Climate Change (IPCC) of underestimating the melt. The thaw of glaciers that stretch out to sea around Svalbard has revealed several islands that are not on any maps.

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waltky · 04-19-2008, 03:05 AM

Salinity imbalance threatens ocean currents...

Deep Antarctic waters freshening
April 18, 2008 - SCIENTISTS studying the icy depths of the sea around Antarctica have detected changes in salinity that could have profound effects on the world's climate and ocean currents.

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The scientists returned to Hobart on Thursday after a one-month voyage studying the Southern Ocean to see how it is changing and what those changes might mean for global climate patterns. Voyage leader Steve Rintoul said his team found that salty, dense water that sinks near the edge of Antarctica to the bottom of the ocean about 5 km down was becoming fresher and more buoyant.

So-called Antarctic bottom water helps power the great ocean conveyor belt, a system of currents spanning the Southern, Pacific, Indian and Atlantic Oceans that shifts heat around the globe. "The main reason we're paying attention to this is because it is one of the switches in the climate system and we need to know if we are about to flip that switch or not,'' said Rintoul of Australia's government-backed research arm the CSIRO.

"If that freshening trend continues for long enough, eventually the water near Antarctica would be too light, too buoyant to sink and that limb of the global-scale circulation would shut down,'' he said on Friday. Cold, salty water also sinks to the depths in the far north Atlantic Ocean near Greenland and, together with the vast amount of water that sinks off Antarctica, this drives the ocean conveyor belt.

This system brings warm water into the far north Atlantic, making Europe warmer than it would otherwise be, and also drives the large flow of upper ocean water from the tropical Pacific to the Indian Ocean through the Indonesia Archipelago. If these currents were to slow or stop, the world's climate would eventually be thrown into chaos. "We don't see any evidence yet that the amount of bottom water that's sinking has declined. But by becoming fresher and less dense it's moving in the direction of an ultimate shutdown.''

More Deep Antarctic waters freshening | NEWS.com.au

waltky · 08-23-2008, 09:57 PM

This'll make a big ol' iceberg...

Greenland Glacier Has Huge Crack
Friday, Aug. 22, 2008 (WASHINGTON) — A growing giant crack and an 11-square-mile chunk of ice hemorrhaging off a prominent glacier in northern Greenland.

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In northern Greenland, a part of the Arctic that had seemed immune from global warming, new satellite images show a growing giant crack and an 11-square-mile chunk of ice hemorrhaging off a major glacier, scientists said Thursday. And that's led the university professor who spotted the wounds in the massive Petermann glacier to predict disintegration of a major portion of the Northern Hemisphere's largest floating glacier within the year. If it does worsen and other northern Greenland glaciers melt faster, then it could speed up sea level rise, already increasing because of melt in sourthern Greenland. The crack is 7 miles long and about half a mile wide. It is about half the width of the 500 square mile floating part of the glacier. Other smaller fractures can be seen in images of the ice tongue, a long narrow sliver of the glacier.

"The pictures speak for themselves," said Jason Box, a glacier expert at the Byrd Polar Research Center at Ohio State University who spotted the changes while studying new satellite images. "This crack is moving, and moving closer and closer to the front. It's just a matter of time till a much larger piece is going to break off.... It is imminent." The chunk that came off the glacier between July 10 and July 24 is about half the size of Manhattan and doesn't worry Box as much as the cracks. The Petermann glacier had a larger breakaway ice chunk in 2000. But the overall picture worries some scientists. "As we see this phenomenon occurring further and further north — and Petermann is as far north as you can get — it certainly adds to the concern," said Waleed Abdalati, director of the Center for the Study of Earth from Space at the University of Colorado.

The question that now faces scientists is: Are the fractures part of normal glacier stress or are they the beginning of the effects of global warming? "It certainly is a major event," said NASA ice scientist Jay Zwally in a telephone interview from a conference on glaciers in Ireland. "It's a signal but we don't know what it means." It is too early to say it is clearly global warming, Zwally said. Scientists don't like to attribute single events to global warming, but often say such events fit a pattern. University of Colorado professor Konrad Steffen, who returned from Greenland Wednesday and has studied the Petermann glacier in the past, said that what Box saw is not too different from what he saw in the 1990s: "The crack is not alarming... I would say it is normal."

However, scientists note that it fits with the trend of melting glacial ice they first saw in the southern part of the massive island and seems to be marching north with time. Big cracks and breakaway pieces are foreboding signs of what's ahead. Further south in Greenland, Box's satellite images show that the Jakobshavn glacier, the fastest retreating glacier in the world, set new records for how far it has moved inland. That concerns Colorado's Abdalati: "It could go back for miles and miles and there's no real mechanism to stop it."

Greenland Glacier Has Huge Crack - TIME