Friday, June 17, 2011

Arctic melts faster than IPCC's forecasts

Deutsche Welle: When the last Intergovernmental Panel on Climate Change (IPCC) report was published in 2007, there was a lack of data on the Arctic, so the panel left a big source of potential sea-level-rise out of its projections for this century. It estimated a conservative rise of about 18 to 59 centimeters. Many scientists have suspected that the IPCC's projections underestimate the pace of change and the latest research appears to back them up.

New findings by the Arctic Monitoring and Assessment Programme (AMAP), a working group of the Arctic Council, reveal unprecedented rates of change in the Arctic Ocean, the mass of the Greenland ice sheet and the region's ice caps and glaciers over the past ten years. The research confirms that warming in the Arctic has been occurring at twice the global average warming trend since 1980.

Surface air temperatures in the Arctic since 2005 have been higher than for any five-year period since measurements began around 1880, and summer temperatures in the region have been higher in the past few decades than at any time in the past 2,000 years.
Although there is a very high degree of variability in the state of sea ice from year to year, Sebastian Gerland – one of the report's contributors from the Norwegian Polar Institute in Tromsö - says long-term monitoring at various points in different Arctic regions shows clear trends: Too little ice, shorter winter seasons when freezing takes place and an early onset of spring and summer melting. "The clarity of that trend is very striking," says the sea ice expert. Indeed, during the last five years, sea ice in the Arctic summer has retreated to its lowest levels since satellite measurements began in 1979.

Gerland stresses that sea ice in the Arctic is not just of local importance. As well as its influence on the ecosystem in the Arctic, it also actively influences the global climate. The white ice floating on top reflects solar radiation back up into the atmosphere. Without it, the heat is absorbed by the dark ocean....

Icebergs in the high Arctic, shot by Mila Zinkova, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

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