A World Wildlife Fund photograph taken along the western shore of Hudson Bay in November 2010 shows a female polar bear with two cubs near Churchill, Canada, in this image released to Reuters on Feb 9, 2011. Polar bear mothers will have a harder time carrying cubs to term as Arctic sea ice dwindles, a new study said, and the US government recognized that Pacific walruses need protection in their melting icy habitat. Arctic ice reached the third-lowest level ever recorded in 2010, and was at record low levels in January. Because the Arctic is a major weather-maker for much of the Northern Hemisphere, these changes are being blamed for severe storms in some of the world's most densely populated areas. [Photo/Agencies]

A park ranger examines the dry bed of Lake Penuelas on the outskirts of Valparaiso, Feb 9, 2011. The central and northern regions of Chile are facing one of the worst droughts in recent years, with reservoirs and dams at low levels, producing an increase in food cost due to crop loss and possible rationing of electricity in the near future, according to local media reports. [Photo/Agencies]