projectpowerplant.com

solonavi 20 December 2006 Climate, General, Global Warming 174 views No Comment Print This Post  Email This Post

www.innovations-report.de

The recent retreat of Arctic sea ice is likely to accelerate so rapidly that the Arctic Ocean could become nearly devoid of ice during summertime as early as 2040, according to new research published in the December 12 issue of Geophysical Research Letters.

The study, by a team of scientists from the National Center for Atmospheric Research (NCAR), the University of Washington, and McGill University, analyzes the impact of greenhouse gas emissions on the Arctic. Scenarios run on supercomputers show that the extent of sea ice each September could be reduced so abruptly that, within about 20 years, it may begin retreating four times faster than at any time in the observed record.

:

Arctic sea ice has retreated in recent years, especially in the late summer, when ice thickness and area are at a minimum. To analyze how global warming will affect the ice in coming decades, the team studied a series of seven simulations run on the NCAR-based Community Climate System Model, one of the world’s leading tools for studying climate change. The scientists first tested the model by simulating fluctuations in ice cover since 1870, including a significant shrinkage of late-summer ice from 1979 to 2005. The simulations closely matched observations, a sign that the model was accurately capturing the present-day climate variability in the Arctic.

:

The research team points to several reasons for the abrupt loss of ice in a gradually warming world. Open water absorbs more sunlight than does ice, meaning that the growing regions of ice-free water will accelerate the warming trend. In addition, global climate change is expected to influence ocean circulations and drive warmer ocean currents into the Arctic.

:

The scientists also conclude that different rates of greenhouse gas emissions can affect the probability of abrupt ice loss. By examining 15 additional leading climate models, they found that if emissions of carbon dioxide and other greenhouse gases were to slow, the likelihood of rapid ice loss would decrease. Instead, summer sea ice would probably undergo a much slower retreat.
:

The study drew on extensive and sophisticated computer modeling recently carried out for the Intergovernmental Panel on Climate Change. The IPCC’s next assessment report will be released early in 2007.