Antarctica's secrets

Marine Ecosystems

Antarctica's secrets

Radar imagery has revealed 150 freshwater lakes beneath the massive Antarctic ice sheet. Getty ImagesThe pitch-black lakes hidden beneath Antarctica’s ice sheet will finally start to release their secrets next year. At a recent meeting, scientists from Russia, the United Kingdom and the United States described their plans to explore the planet’s last uncharted ecosystems by drilling into three very different examples of these subglacial lakes.

Over the past 40 years, radar imagery has revealed around 150 freshwater lakes of various sizes and ages beneath the massive Antarctic ice sheet. Some have been isolated from the outside world for millions of years, raising the possibility that they hold unique life forms. The dark, nutrient-deprived environment of the lakes could resemble conditions on Jupiter’s moon Europa, which is assumed to hold a large ocean beneath its frozen surface.

Scientists have longed to draw samples from the lakes, but technical problems and environmental concerns have slowed their progress. Now, the Russian team expects to reach its quarry, Lake Vostok, by February 2011. The Americans and British will follow several years later with forays into lakes with different hydrological and geological characteristics.

“Over the next few years we’ll be able to explore a continental-scale ecosystem that has never before been sampled,” says Robin Bell, a senior researcher at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. “This is a madly exciting endeavour.”

Home to ancient microbial life

Lake Vostok is the best known and largest of the subglacial lakes, measuring roughly the size of Lake Ontario. Buried beneath almost 4,000 meters of ice in eastern Antarctica, the lake is thought to be 35 million years old and could host ancient microbial life.

“It’s like going fishing in the Everglades, in the Rocky Mountains and in Northern Canada.”

Russian drillers had planned to penetrate the lake in the 2008-09 Antarctic field season, but their drill got stuck 80 metres above the lake surface. All technical problems have been resolved during the past field season, says Valery Lukin, director of the Russian Antarctic programme, who spoke at the meeting, held by the American Geophysical Union in Baltimore, Md.

Some researchers worry that a Russian success could come at the cost of biological and chemical contamination of the pristine waters. “Let’s hope they don’t spoil the lake,” says Robert Bindschadler, a glaciologist at NASA’s Goddard Space Flight Centre in Greenbelt, Md.

Plans to protect Lake Vostok

Lukin says that his country’s team has come up with plans to safeguard Lake Vostok. The team will cut through the ice using a heated drill, with non-toxic silicone oil serving as the lubricating fluid. It will also explore the lake in stages; at first it will only suck up a water sample before allowing the bottom of the hole to refreeze. Plans for lowering instruments into the lake to explore the bottom sediment will be postponed until an extra environmental assessment has been completed.

The Antarctic Treaty’s committee for environmental protection is expected to approve the Russian plans in October, although there is no official requirement for the team to wait until then.

“The Russians are trying very hard to do it right, and that means a lot,” says Bell. At the meeting, US and British researchers described their longer-term plans for exploring subglacial lakes on the opposite side of the pole. Lake Ellsworth, a relatively small lake in western Antarctica, is the target for researchers from the British Antarctic Survey. And over the next two field seasons, US researchers will conduct radar surveys from the surface to study Lake Whillans near Antarctica’s Ross Ice Shelf, says Ross Powell, a geologist at Northern Illinois University in DeKalb. The US$20-million Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project, which Powell oversees, plans to drill into the lake during the 2012-13 field season.

Lake Whillans has a subsurface connection with the ocean beneath the ice shelf, making it more dynamic than isolated lakes such as Vostok.

NYT News Service

New light shed on North Pole ice trends

Latest research shows that while a decades-long trend toward thinner and sparser ice looks to continue, with warming from greenhouse gases and soot contributing to the change, expect a lot of variability along the way to a projected open-water summertime Arctic. When the extent of the pack of sea ice drifting around the North Pole hit a remarkable low in 2007, the resulting, and persistent, front-page thought was that the system was in a “death spiral” far more dramatic than any climate model had foreseen.

Even in 2007, some Arctic climate and ice specialists were warning that the ice retreat was “as much a result of ice moving as melting,” adding that the unpredicted changes could just as easily betray weaknesses in climate models as hints of some accelerating meltdown.

A new study scheduled for publication in Geophysical Research Letters supports the earlier research on the importance of winds in shaping the fate of sea ice both year to year and over recent decades.

The authors, Masayo Ogi and Koji Yamazaki in Japan and John M Wallace of the University of Washington, concluded that the combined effects of winter and summer wind patterns have accounted for half of the change in the minimum sea ice extent from one summer to the next and about a third of the overall downward trend in sea ice extent over the last three decades.

The bottom line, expressed here before, is that no one should expect to find much broad meaning in short-term variability in Arctic sea ice — in one direction or the other. If there is a death spiral, expect a lot of loop the loops along the way. 

Some commentators have made much of  longer-term trends in ice thickness, but there, too, winds and patterns of atmospheric pressure have played a powerful role over longer time spans.

Andrew C Revkin
NYTNS

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