Thursday, October 18, 2012

New satellite images show the polar ice cover

decline in extent and thickness

graph: the reduction of the ice. Credit: Giulio Frigieri

Arctic sea ice is disappearing at a much faster pace than expected, according to the first satellite built specifically established to study the ice caps of Earth.

Preliminary results of CryoSat-2 probe of the European Space Agency show that 900 cubic kilometers of sea ice in the Arctic Ocean were disappeared during the last year.

This loss rate is 50% higher than most of the scenarios described by polar scientists suggests that global warming, caused by increasing emissions of greenhouse gases, is currently have a significant impact in the region. In recent years, the Arctic Ocean could be ice-free in summer, causing a race to the exploitation of fishery resources, oil, minerals, and sea routes.

Using instruments aboard satellites above, scientists have found that the area covered by summer sea ice in the Arctic has decreased rapidly. But new measurements indicate that the ice has dramatically during thinning. For example, in the northern regions of Canada and Greenland, where ice thickness regularly stayed at about five to six meters was a decade ago, the levels were reduced to between one and three meters.

"Preliminary analysis of the data indicates that the rate of volume loss of the Arctic sea ice in summer can be much larger than what I had already suspected," said Dr Seymour Laxon, the Centre for Polar Observation and Modelling, University College London (UCL), where data from CryoSat-2 is being analyzed. "Very soon, we will be able to experience the iconic moment when, one summer day, you look at the satellite images and do not see the sea ice cover in the Arctic, while open water."

The consequences of the loss of ice cover in the Arctic, but only for part of the year, can be profound. Dull white cap to reflect sunlight back into space, the area is heated more than the present. As a result, the temperature of the oceans will rise and methane deposits in the deep ocean could melt, evaporate and bubbles in the atmosphere. Scientists reported evidence that methane plumes appear in many areas. Methane is a powerful greenhouse and particularly higher levels of it in the atmosphere is only likely to accelerate global warming. And with the disappearance of sea ice off the coast of Greenland, the glaciers are melting faster and could raise sea levels faster than today.

UCL Professor Chris Rapley, said: "With the temperature gradient between the Arctic and the Equator fall, as is the case now, it is also possible that the jet stream in the upper atmosphere could become more unstable it could. means increased volatility by time in low latitudes, similar to the one experienced this year. "

coverage of sea ice in the Arctic varies considerably throughout the year, with a peak in March. By combining ICESat previous results and data from other studies, including measurements by submarines traveling under the polar ice cap, Laxon said preliminary analysis already given a clear indication of the loss of Arctic sea ice in the quarterfinals final years, both in winter and summer.

In winter 2004, the volume of sea ice in the central Arctic was about 17,000 cubic kilometers. This winter was 14,000 according CryoSat.

However, the numbers of summer offer the actual download. In 2004, there were about 13,000 cubic kilometers of sea ice in the Arctic. In 2012, is 7000 cubic kilometers, almost half of the figure eight years ago. If the current annual loss of about 900 cubic kilometers of continuous ice cover in summer could vanish in ten years in the Arctic.

But Laxon urged caution, saying. "First of all, this is based on preliminary figures CryoSat, so you should be careful before jumping to conclusions over the current rate of decline in the volume of ice could change." But experts say computer models show that rate decreased volume of ice is only likely to increase in the next decade.

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