Earth's Arctic freezer turning into hothouse

The world is losing its northern freezer as Arctic winter ice is in sharp decline, NASA scientists reported this week. Even with below average winter temperatures, Arctic ice is thinner and covers less area than it did a decade ago. Arctic sea ice is the cooling mechanism for the global climate system. As it declines and the region warms - already three to five degrees Celsius warmer - then inevitably there are local, regional and hemispheric climate impacts. "We've already lost one third of the summer ice cover since the 1980s. There are already impacts from this," says Ron Kwok of NASA's Jet Propulsion Laboratory in Pasadena. "A completely ice-free summer by 2013 is not impossible," Kwok said in a telephone news conference. "You would have been laughed out the room if you suggested this five years ago." The new study shows that the maximum extent of the 2008-2009 winter sea ice cover was the fifth-lowest since researchers began collecting such information 30 years ago. The past six years have produced the six lowest maximums in that record. More stunning, and indicative of the rapid warming of the region, is the decline in the thick, hard-to-melt multi-year ice, says Walter Meier, research scientist at the National Snow and Ice Data Centre in Boulder, Colorado. Multiyear ice is ice that is two or more years old and therefore doesn't melt in the summer. "Less than 10 percent is multiyear now. It used to be 30 percent in 1981," Meier said at the news conference. Polar amplification is the reason why climate change is warming the Arctic far faster than anywhere else. A combination of processes and feedbacks in the region have resulted a three to five degree Celsius warming already. In 50 to 100 years time if average global temperature rises three degrees Celsius, the Arctic freezer will be a hothouse - at least 10 degrees Celsius warmer. "The polar cryosphere has long existed as a buffer against [global] climate warming to an extent," Dick Peltier, Director of the Centre for Global Change Science at the University of Toronto, told IPS. The Earth's great northern freezer is undergoing "great transformations of energy" away from cooling and shifting to warming. More ice melt means more open water resulting in more of the sun's energy being trapped in the Arctic Ocean and warming water temperatures. That means winter freeze-up comes later, the ice is thinner, and more likely to melt when summer returns. This positive feedback loop is already operating and the meltdown of the Arctic sea ice looks to be irreversible he says. "It's a bit like a flywheel now able to turn with reckless abandon." The loss of Arctic sea ice won't raise sea levels directly but as it acts to warm the entire region that will affect the massive Greenland ice sheet. If the whole ice sheet were to melt it would result in a six to seven-metre sea-level rise. Recent studies report thinning at the margins of the Greenland ice sheet, an increased fresh water discharge from outlet glaciers, and a significant increase in surface melt, NASA reported in a release. The current Arctic meltdown is already changing the local climate and having impacts on northern peoples, Meier said. "No Arctic ice in the summer will result in profound changes," says Peltier. Meanwhile weather patterns in the Arctic have already changed with a northward deepening of the North Atlantic Oscillation (NAO), says Peltier. The NAO controls the strength and direction of westerly winds and storm tracks across the Arctic and North Atlantic. The jet stream has also shifted further north as the Arctic warms. The jet stream is a fast-flowing westward current of air approx 10 kilometres above the ground. It is the boundary zone between the warm tropical air mass of the south and the cold polar Arctic air mass. Less ice in the Arctic weakens the cold polar air and the jet, while continuing its ebb and flow as seen on daily weather maps, is incrementally pushing northwards altering local weather patterns. "There has been a northward shift in precipitation, with more rain falling on the northern boreal regions while the southern U.S. is becoming drier," says Peltier. Although those observed changes are not directly attributable to the Arctic ice loss, but to climate change overall. However there is no doubt that the Arctic meltdown "will eventually affect our weather," he says. The rapid warming of the Arctic has happened so quickly that scientists have only begun to study what the potential implications may be. Chief among their concerns is the vast region of permafrost that covers one quarter of the land surface of the Northern hemisphere. The permanently frozen bog and peatland contains enormous amounts of organic carbon - perhaps enough to triple the amount currently in the atmosphere, as previously reported by IPS. As the permafrost melts carbon dioxide and the more potent greenhouse gas methane is released. And that seems to have been the case during the extremely warm northern summer of 2007 when global atmospheric methane levels shot up by several million tonnes after having been stable for more than a decade. However there is no smoking gun pointing to permafrost. "Our abilities to detect how much and where methane is being released is really bad," says Peltier. And there is no "predictive capacity" to get some insight into what might happen to permafrost and when. The International Panel on Climate Change (IPCC) has made permafrost a priority for its next major report in four or five years time, he said. "There is clear potential for large methane releases."