Pictures of the Decade : Climate activists Lesley Butler and Rob Bell "sunbathe"

Climate activists Lesley Butler and Rob Bell "sunbathe" on the edge of a frozen fjord in the Norwegian Arctic town of Longyearbyen. Global warming became one of the world's major concerns of the decade amid mounting evidence that human activity is disrupting the climate. By 2007 the Intergovernmental Panel on Climate Change was saying it was "very likely" - at least 90 percent certain -- that humans are to blame for most of the observed warming trend of the past 50 years. It also said that warming of the planet was "unequivocal." Taken on April 25, 2007 by Francois Lenoir