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March 06 2012

16:59

February 08 2012

16:49

On Our Radar: A Subglacial Lake

Scientists say they have drilled down through ice and reached Lake Vostok, the largest of more than 280 lakes under the thick ice that covers most of the Antarctic continent. It has been sealed from light and air for millions of years. If evidence of life is found there, it could boost hopes of finding life in similar conditions in icy water on one of the moons of Jupiter.
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August 25 2011

17:40

50 Million Year Old Fossil Clams Shed Light on El Nino and Global Warming


One current climate theory suggests that global warming could result in El Nino conditions becoming permanent as opposed to occurring in prevailing two-to seven-year cycles. New research based on a study of a long-lived species of fossilized clam that lived of the coast of Antarctica indicates that was not the case during the early Eocene, when the Earth was as warm as it’s been in the last 65 million years.

El Nino is characterized by unusually warm ocean temperatures in the eastern equatorial Pacific, which can result in torrential rains in Peru and drought in Australia. It’s “the warm phase of a large oscillation in which the surface temperature of the tropical Pacific varies, causing changes in winds and rainfall patterns,” explains the Physorg,com report. The complete phenomenon is known as the El Nino Southern Oscillation, or ENSO.

Prevailing climate theory suggests that global warming could cause the ENSO to collapse and would result in permanent El Nino conditions.

New research conducted by a team led by Syracuse University researcher Linda Ivany suggest otherwise, however. Ivany led an international team that studied a species of fossilized clam that could live more than 100 years during a time when Antarctica was as warm as Virginia is today. It turns out that the clams’ growth rings can be analyzed akin to the way tree rings are analyzed, providing a long-term picture of ancient climatic conditions.

The team found that the distances between consecutive bands in the clams’ shells varied with a two-to seven-year periodicity typical of El Nino’s periodicity. They also found the same pattern in fossilized driftwood found buried in sediments along with the clams.

“While it might sound counterintuitive, it turns out that the inter-annual climate variations seen in the tropical Pacific today are strongly teleconnected to the Antarctic. This seems to have also been the case 50 million years ago,” Ivany said.

“The good news is that despite the very warm temperatures during the Eocene, the evidence from the clams and tree rings shows that the ENSO system was still active, oscillating between normal and El Niño years. That suggests that the same will be true in our future as the planet warms up again.”

Image Credit: Rick Schrantz, Kentucky Paleontological Society

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June 28 2011

22:18

Shifting Ocean Currents Drive Accelerating Ice Melt of Antarctic Ice Shelf


Shifting currents are eating away at the Pine Island Ice ShelfShifting ocean currents appear to be accelerating ice melt of the Pine Island Glacier Ice Shelf in western Antarctica.

According to research published this week in the journal Nature Geoscience, scientists from the Lamont-Doherty Earth Observatory at Columbia University have recorded ocean currents driving at and underneath the ice shelf, carving out an expanding cavity from underneath the glacier, creating a growing impact 50 percent greater than when scientists began monitoring the region in the early 1990′s.

Researchers estimate that 2.5 miles of glacier now slide into the sea annually.

In a summary report, scientists say the rapid rate of deterioration of the Pine Island Glacier could significantly impact coastlines around the globe:

“Pine Island Glacier, among other ice streams in Antarctica, is being closely watched for its potential to redraw coastlines worldwide. Global sea levels are currently rising at about 3 millimeters (.12 inches) a year. By one estimate, the total collapse of Pine Island Glacier and its tributaries could raise sea level by 24 centimeters (9 inches).”

The accelerating trend of ice can’t be accounted for solely from the modest 0.2 degree Celsius increase in surrounding ocean temperature observed at Pine Island over the past fifteen years. Scientists point to evidence of stronger winds in the Southern ocean that are shifting currents, pushing warmer waters from the tropics toward the ice shelf. That warmer water pushes further underneath the glacier, leading to the observed rate of destabilization and the growing chasm underneath.

Authors of the report cite the phenomenon impacting western Antarctica as further indication of the “multiplier effect” climate change has on regional ecosystems. Eric Rignot, a senior scientist a the NASA Jet Propulsion Laboratory who participated in the study, explained in a statement coinciding with the publication of the research:

“The main reason the glaciers are thinning in this region, we think, is the presence of warm waters,” said Rignot. “Warm waters did not get there because the ocean warmed up, but because of subtle changes in ocean circulation. Ocean circulation is key. This study reinforces this concept.”

Additional sources and further reading:
Climatewire (subscription required)

 

Image credit: NASA, courtesy Flickr

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March 22 2011

00:06

March 11 2011

14:07

Polar Ice Loss Is Accelerating, Scientists Say

The increasing ice loss means that for the first time, Greenland and Antarctica appear to be adding more to sea-level rise than the world's other reserves of ice -- primarily mountain glaciers, which are also melting because of rising temperatures.

March 03 2011

19:00

A Big Surprise Beneath the Ice

A new study shows that ice melts far more extensively at the base of the Antarctic ice sheet, miles below the surface, than scientists had thought. The findings raise the possibility that melt water may even help govern the behavior of glaciers.
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October 18 2010

20:14

April 26 2010

05:34

Research in Antarctica Reveals Non-Organic Mechanism for Production of Important Greenhouse Gas

http://www.sciencedaily.com/releases/2010/04/100425151148.htm ScienceDaily (Apr. 25, 2010) — In so many ways, Don Juan Pond in the Dry Valleys of Antarctica is one of the most unearthly places on the planet. An ankle-deep mirror between mountain peaks and rubbled moraine, the pond is an astonishing 18 times saltier than the Earth’s oceans and virtually never freezes, even in [...]

January 15 2010

23:00

Antarctica is Losing Ice Quickly, Melting Away Another Climate Skeptic Myth

Two popular climate skeptic "facts" which are claimed to disprove anthropogenic global warming are:

1.  Surface ice melting on Antarctica is decreasing.

2.  Sea ice around Antarctica is increasing.

Despite what climate skeptics assert, neither of these arguments disprove global warming.  Actually, they highlight quite the contrary:  Antarctica is in fact losing mass (ice).  Even more, ice is melting and breaking away from the continent at an incredibly accelerating rate. 

This isn't opinion, there is data to prove it.

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A recent article published by NASA thoroughly explains why these arguments are misleading.  The article also offers multiple streams of scientific data to show how alarming the rate of glacial retreat on Antarctica is.

Data from NASA's Grace satellite shows that Antarctica is losing 100 cubic kilometers (24 cubic miles) of ice per year.  More alarming, still, is the increase in the rate of disintegration.  The article points out that ice can flow without melting, which illuminates how moot the skeptics' first argument is, as well as clarifying the reason behind their second claim.

The majority of the melting of the Antarctic ice sheet is occurring in Western Antarctica.  Western Antarctica is a series of islands covered by ice, which NASA describes as a "frozen Hawai'i."  According to data accumulated by NASA's Jet Propulsion Laboratory, Western Antarctica's largest ice stream, the Pine Island Glacier is retreating.  This year a British scientific group not only verified NASA's data, but also showed that the retreat of the Pine Island Glacier quadrupled between 1995 and 2006.  If this glacier melts, scientists estimate it would raise sea levels by 1.6 to 2.3 feet.

A major reason for the accelerating retreat of Western Antarctica's glaciers is the warming of the sea water surrounding Antarctica.  Warm water is highly problematic for ice shelves.  Ice shelves are the portion of a glacier that extends beyond land mass and out into the water.  As a result, their intrinsic icy structures are highly vulnerable to warm water--problem number one. 

Problem number two:  ice shelves act as a buffer wall which slows the flow of ice toward the water.  So, eliminating a glacier's ice shelve is like removing the door from an over-stuffed closet--most of the contents spill out.  In the case of Western Antarctica this is a very scary prospect considering if the ice covering Western Antarctica melted, it would raise sea levels 16 to 23 feet.  Later this year, NASA will undertake an expedition to rigourously test if Antarctica's warmer water is undermining its ice shelves.

But, don't worry, "sea ice around Antarctica is growing," exclaim climate skeptics.

Yes, because it is spilling forth from the mainland.

The growth of ice surrounding Antarctica reflects a scary global warming trend since it is a result of the Antarctic ice sheet losing mass.  And, as Isabella Velicogna of the Jet Propulsion Laboratory and the University of California, Irvine, says, "The important message is that it is not a linear trend. A linear trend means you have the same mass loss every year. The fact that it’s above linear, this is the important idea, that ice loss is increasing with time."

 

November 20 2009

00:00

Antarctic temperatures between ice ages '6C warmer than today'

Temperatures in Antarctica during warm periods between ice ages soared to up to 6C warmer than the present day a study has shown.
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