Abrupt ice retreat could produce ice-free arctic summers by 2040




The research was funded by the National Science Foundation, NCAR's principal sponsor, as well as by NASA.

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.


Why expect abrupt change?

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.


Avoiding abrupt change

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.

"Our research indicates that society can still minimize the impacts on Arctic ice," Holland says.

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.



About the article:
Journalists who agree to abide by the embargo may obtain a preprint of the article by contacting David Hosansky at hosansky@ucar.edu

Title: Future Abrupt Reductions in the Summer Arctic Sea Ice
Publication: Geophysical Research Letters, December 7, 2006

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