Guest guest Posted December 13, 2006 Report Share Posted December 13, 2006 Drastic speedup in Arctic melting forecast Dec. 11, 2006Courtesy National Center for Atmospheric Researchand World Science staff Recent melting of Arctic sea ice is likely to speed up so rapidly that Arctic Ocean summers could be nearly ice-free as early as 2040, according to new research.A study published last year claimed that this would happen by this century’s end. Thus the new forecast moves the date forward a few decades. Two frames from a simulation showing the approximate extent of Arctic sea ice in September. The top image is from 2000; the bottom, from 2040. This is a likely scenario unless greenhouse gas emissions are significantly curtailed, researchers say. (Courtesy NCAR) The study, published in the Dec. 12 issue of the journal Geophysical Research Letters, is by scientists from the U.S. National Center for Atmospheric Research in Boulder, Colo., and other institutions.The research analyzes the impact on the Arctic of “greenhouse gas” emissions. These are gases, including carbon dioxide, produced partly by human activities and believed to be largely responsible for dramatic global warming in recent decades.Scientists believe the trend may lead to environmental cataclysm. The Arctic is one of the earliest regions affected. Among other things, drownings of polar bears and walrus pups have been reported with the melting of ice on which the animals live.Supercomputer simulations show that sea ice each September could shrink so abruptly that, within two decades, it may begin retreating four times faster than at any time in the observed record, the authors of the new study say.“We have already witnessed major losses in sea ice, but our research suggests that the decrease over the next few decades could be far more dramatic than anything that has happened so far,” said the center’s Marika Holland, lead author of the study. “These changes are surprisingly rapid.”Arctic sea ice has retreated in recent years, especially in the late summer, when ice is at a minimum. The research team cited several reasons for the abrupt loss of ice. Open water absorbs more sunlight than does ice, so growing regions of ice-free water would accelerate the warming trend. And global climate change is expected to influence ocean circulations and drive warmer ocean currents into the Arctic. It’s a “feedback loop with dramatic implications for the entire Arctic region,” Holland said.* * * Quote Link to comment Share on other sites More sharing options...
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