03 October 2007

Calota polara de la Polul Nord impinsa de vant

Calota polara de la Polul Nord a scazut dramatic in ultimii ani si mai ales anul asta. Link. Deja e tot mai clar ca nu poate fi vorba de o variatie naturala. Se pare ca anul asta topirea a fost mai mare decat se asteptau oamenii de stiinta pentru ca vantul a impins calota glaciara!
Complicating the picture, the striking Arctic change was as much a result of ice moving as melting, many say. A new study, led by Son Nghiem at NASA’s Jet Propulsion Laboratory and appearing this week in Geophysical Research Letters, used satellites and buoys to show that winds since 2000 had pushed huge amounts of thick old ice out of the Arctic basin past Greenland. The thin floes that formed on the resulting open water melted quicker or could be shuffled together by winds and similarly expelled, the authors said. ... While experts debate details, many agree that the vanishing act of the sea ice this year was probably caused by superimposed forces including heat-trapping clouds and water vapor in the air, as well as the ocean-heating influence of unusually sunny skies in June and July. Other important factors were warm winds flowing from Siberia around a high-pressure system parked over the ocean. The winds not only would have melted thin ice but also pushed floes offshore where currents and winds could push them out of the Arctic Ocean.
Se estimeaza ca in vreo 20-30 de ani vor putea exista curse regulate peste Oceanul Arctic.
Many Arctic researchers warned that it was still far too soon to start sending container ships over the top of the world. “Natural variations could turn around and counteract the greenhouse-gas-forced change, perhaps stabilizing the ice for a bit,” said Marika Holland, of the National Center for Atmospheric Research in Boulder, Colo. But, she added, that will not last. “Eventually the natural variations would again reinforce the human-driven change, perhaps leading to even more rapid retreat,” Dr. Holland said. “So I wouldn’t sign any shipping contracts for the next 5 to 10 years, but maybe the next 20 to 30.”