Ice melt at north pole

The rate of climate warming over northern Alaska, Canada, and Russia could more than triple during extended episodes of rapid sea ice loss, according to a new study from the National Center for Atmospheric Research (NCAR) and the National Snow and Ice Data Center (NSIDC). The findings raise concerns about the thawing of permafrost, or permanently frozen soil, and the potential consequences for sensitive ecosystems, human infrastructure, and the release of additional greenhouse gases.

“The rapid loss of sea ice can trigger widespread changes that would be felt across the region,” said Andrew Slater, NSIDC research scientist and a co-author on the study, which was led by David Lawrence of NCAR. The findings will be published Friday in Geophysical Research Letters.

Last summer, Arctic sea ice extent shrank to a record low. From August to October last year, air temperatures over land in the western Arctic were also unusually warm, reaching more than 4 degrees Fahrenheit (2 degrees Celsius) above the 1978-2006 average. This led the researchers to question whether the unusually low sea ice extent and warm land temperatures were related.

Lawrence, Slater, and colleagues used a climate model to explore the relationship between low sea ice extent, increased air temperatures, and permafrost thawing. Previous climate change simulations identified periods of rapid sea ice loss that last 5 to 10 years. The new study shows that during such episodes, Arctic land would warm 3.5 times faster than average rates of warming predicted by global climate models for the 21st century.

The findings point to a link between rapid sea ice loss and enhanced rate of climate warming, which could penetrate as far as 900 miles inland. In areas where permafrost is already at risk, such as central Alaska, the study suggests that periods of abrupt sea ice loss can lead to rapid soil thaw.

Thawing permafrost may have a range of impacts, including buckled highways and destabilized houses, as well as changes to the delicate balance of life in the Arctic. In addition, scientists estimate that Arctic soils hold at least 30 percent of all the carbon stored in soils worldwide. While scientists are uncertain what will happen if this permafrost thaws, it has the potential to contribute substantial amounts of greenhouse gases to the atmosphere.



Source: http://nsidc.org/news/press/20080610_Slater.html