Monday, August 13, 2012

Rate of Arctic summer sea ice loss is 50% higher than predicted

New satellite images show polar ice coverage dwindling in extent and thickness

Sea ice in the Arctic is disappearing at a far greater rate than previously expected, according to data from the first purpose-built satellite launched to study the thickness of the Earth's polar caps.
Preliminary results from the European Space Agency's CryoSat-2 probe indicate that 900 cubic kilometres of summer sea ice has disappeared from the Arctic ocean over the past year.
This rate of loss is 50% higher than most scenarios outlined by polar scientists and suggests that global warming, triggered by rising greenhouse gas emissions, is beginning to have a major impact on the region. In a few years the Arctic ocean could be free of ice in summer, triggering a rush to exploit its fish stocks, oil, minerals and sea routes.
Using instruments on earlier satellites, scientists could see that the area covered by summer sea ice in the Arctic has been dwindling rapidly. But the new measurements indicate that this ice has been thinning dramatically at the same time. For example, in regions north of Canada and Greenland, where ice thickness regularly stayed at around five to six metres in summer a decade ago, levels have dropped to one to three metres.
"Preliminary analysis of our data indicates that the rate of loss of sea ice volume in summer in the Arctic may be far larger than we had previously suspected," said Dr Seymour Laxon, of the Centre for Polar Observation and Modelling at University College London (UCL), where CryoSat-2 data is being analysed. "Very soon we may experience the iconic moment when, one day in the summer, we look at satellite images and see no sea ice coverage in the Arctic, just open water."
The consequences of losing the Arctic's ice coverage, even for only part of the year, could be profound. Without the cap's white brilliance to reflect sunlight back into space, the region will heat up even more than at present. As a result, ocean temperatures will rise and methane deposits on the ocean floor could melt, evaporate and bubble into the atmosphere. Scientists have recently reported evidence that methane plumes are now appearing in many areas. Methane is a particularly powerful greenhouse gas and rising levels of it in the atmosphere are only likely to accelerate global warming. And with the disappearance of sea ice around the shores of Greenland, its glaciers could melt faster and raise sea levels even more rapidly than at present.
Professor Chris Rapley of UCL said: "With the temperature gradient between the Arctic and equator dropping, as is happening now, it is also possible that the jet stream in the upper atmosphere could become more unstable. That could mean increasing volatility in weather in lower latitudes, similar to that experienced this year."
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Tuesday, August 7, 2012

Alaskan Arctic villages hit hard by climate change

Fermented whale’s tail doesn’t taste the same when the ice cellars flood.

Whaling crews in this Arctic coast village store six feet of tail — skin, blubber and bone — underground from spring until fall. The tail freezes slowly while fermenting and taking on the flavor of the earth.

Paying homage to their connection to the frozen sea, villagers eat the delicacy to celebrate the moment when the Arctic’s ice touches shore.
But climate change, with its more intense storms, melting permafrost and soil erosion, is causing the ice cellars to disintegrate. Many have washed out to sea in recent decades. The remaining ones regularly flood in the spring, which can spoil the meat and blubber, and release scents that attract polar bears.