The American Association for the Advancement of Science (AAAS) has reaffirmed the position of its Board of Directors and the leaders of 18 respected organizations, who concluded based on multiple lines of scientific evidence that global climate change caused by human activities is now underway, and it is a growing threat to society.
http://www.aaas.org/news/releases/2009/1204climate_statement.shtml?sa_campaign=Internal_Ads/AAAS/RSS_News/2009-12-04/