Summer sea-ice extent in the Arctic has decreased greatly during recent decades. Simulations of twenty-first-century climate suggest that the ice can recover from artificially imposed ice-free summer conditions within a couple of years.

As Royal Dutch Shell and other oil companies prepare to drill offshore in the Alaskan Outer Continental Shelf (OCS), a new report commissioned by the Washington, DC–based Pew Environment Group concludes current response capabilities aren’t adequate to contain and clean up a major spill in the area.1 Marilyn Heiman, who directs the group’s U.S. Arctic program, says drilling on the Alaskan OCS requires a science-based precautionary approach. “And right now, we don’t know enough about the potential consequences of a spill to the ecosystem,” she says.

The Arctic is responding more rapidly to global warming than most other areas on our planet. Northward-flowing Atlantic Water is the major means of heat advection toward the Arctic and strongly affects the sea ice distribution. Records of its natural variability are critical for the understanding of feedback mechanisms and the future of the Arctic climate system, but continuous historical records reach back only ~150 years. Here, we present a multidecadal-scale record of ocean temperature variations during the past 2000 years, derived from marine sediments off Western Svalbard (79°N).

Hybridization in polar species could hit biodiversity hard, say Brendan Kelly, Andrew Whiteley and David Tallmon.

On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world