New data indicates the continuation of a long-term decline in summer ice underway since at least 1979. Researchers say roughly half the decline can be attributed to global warming.
An unusually warm January has limited the return of Arctic sea ice, whose extent set a record low for the month. The ice's ability to reflect sunlight back into space has a significant influence on climate worldwide.
The seasonal cooling effect of light-reflecting snow and ice in the Northern Hemisphere may be weakening at twice the rate predicted by climate models, a new study shows, accelerating the impact of global warming.