Trick-or-treating in Fairbanks, Alaska, deep in the state's interior, tends to be a parka-and-mukluks affair. Some 13 years ago, Larry Hinzman recalls, he and his young daughters endured Halloween temperatures that plummeted to 30 degrees below zero F. as they shuffled through the neighborhood. This year, however, the Halloween forecast calls for a relatively balmy 8 below F., capping a month where temperatures often have hovered near freezing. For October in Fairbanks, "that's not unusual. That's mutant," says Dr. Hinzman, a University of Alaska hydrologist.
The Arctic has long been viewed as the canary in the coal mine for global warming. Now, say many researchers, the canary not only is teetering on its perch; it may have reached the tumbling point. To monitor such changes more closely, scientists globally have launched a scientific field assault in the region. Earlier this month, the International Council for Science met in Suzhou, China, and formally launched the International Polar Year slated to run from 2007 to 2008.
In addition, representatives from national and international scientific organizations are scheduled to meet in Copenhagen, Denmark, next month to lay out an ambitious 10- to 15-year polar science agenda, which will extend the IPY's yearlong effort. The intense examination is likely to be fueled by a series of recent studies, including one Dr. Hinzman and colleagues have published in the current issue of the journal Climatic Change: signs of change are showing up just about everywhere researchers look.
The signs are seen in shrinking summer sea ice, the northward march of tree and shrubs, and longer periods from spring to fall when the ground is snow-free. But perhaps more telling, scientists say they see evidence that the changes are beginning to feed on themselves, building momentum for which researchers say they currently see no effective brakes. Scientists say this acceleration comes from "positive feedbacks" - self-reinforcing trends, which are the climate's version of irritating squeals from mishandled sound gear at a rock concert. If left unchecked by countervailing forces, positive feedbacks have the potential to destablize the Earth's climate, tipping it into a new regime.
Not so long ago, these feedbacks appeared largely in computer simulations of human-induced climate change. Now, research groups are openly asserting in peer-reviewed journals that these feedbacks are taking hold in the world of snow and ice gauges, stream flow measurements, satellite images, and core samples. "What used to be whispered in a speculative way - hey, do you think the feedbacks are kicking in - is more like: It's starting to look like the feedbacks may be kicking in," says Donald Perovich, an Arctic sea-ice specialist at the US Army Corps of Engineers' Cold Regions Research and Engineering Laboratory in Hanover, N.H.
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http://www.csmonitor.com/2005/1031/p03s01-sten.html
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