While many scientists have long been following the pronounced summer warming in the Arctic, a recent scientific study takes Arctic research one step further by assessing the feedbacks between land surface changes due to summer warming and the implications for future summer warming. One new study shows that atmospheric warming has led to a lengthened snow-free season in arctic Alaska, which has in turn led to terrestrial changes, such as shrub and tree expansion.

• Chapin III, F.S. et al. "Role of Land Surface Changes in Arctic Summer Warming." Science 310(5748): 657-660 (28 October 2005). Science Express on 22 September 2005 at www.sciencemag.org

Chapin et al. show that land surface changes provide a positive feedback, and augments atmospheric warming by a factor of two to seven. They suggest that terrestrial transformations will increase local atmospheric warming by roughly three watts per square meter per decade (similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric CO2). In turn, the rate of summer warming will increase significantly, magnifying climate change impacts in Arctic communities and ecosystems. The study's authors posit that summer warming will be further amplified as a result of ongoing additional land surface changes.

Implications: Many species of arctic animals can only prosper under current conditions of ice and snow -- including popular megafauna such as the polar bear and the arctic seal. Changes in vegetation as well as in temperature will reduce the aerial extent of their habitat. Increased warming will have other consequences as well: subsistence communities, livelihoods may be threatened, and many human infrastructures that rely on winter ice cover (for example, ice roads for haulage to Alaska's North Slope oil wells) may have a reduced capacity due to such changes.