Arctic could be free of sea ice in the summer ‘in a decade’

Sea ice in the Arctic is disappearing at a rate 50% faster than projected by scenarios prepared by polar scientists according to new data from the CryoSat-2 probe. The probe, the first purpose built satellite to study the thickness of the polar ice caps has revealed that in areas north of Canada and Greenland, the thickness of summer ice has dropped to one to three metres, from five to six metres a few years’ ago.

Scientists analysing the data at University College London commented to the Guardian that the results suggest that ‘very soon’ the Arctic could be completely free of ice during the summer. In 2004, there was 13,000 cubic kilometres of ice in the Arctic in the summer. Now, eight years later, the figure is 7,000 cubic kilometres. If the annual rate of loss of 900 cubic kilometres of ice continues, the Arctic could be free of ice in the summer in a decade.

The melting of the Arctic ice cap is likely to have tremendous consequences for world weather patterns, sea-level rise and greenhouse gas concentrations in the atmosphere. For example, a reduced temperature gradient from the Arctic to the equator could lead to instability in the jet stream in the upper atmosphere, leading to increased volatility in the weather at lower latitudes. A reduction in the albedo of the Arctic, caused by lower ice cover, means that less solar radiation is reflected by the Earth’s surface, leading to increased warming. As the ocean at the poles warms, methane deposits (clathrates) on the ocean’s floor melt, releasing plumes of methane (which is a greenhouse gas with a stronger effect than carbon dioxide).

Calibration of the data collected by CryoSat-2, through experiments by scientists in the Arctic, low-flying planes and underwater sonar, has revealed that the data on ice thickness are correct to within 10 cubic centimetres. CryoSat-2 is a project funded by the European Space Agency (ESA).

Source article: Rate of Arctic summer sea ice loss is 50% higher than predicted. Robin McKie, 11th August 2012, the Guardian.