FILE - In this Dec. 7, 2009, file photo, demonstrators block the main entrance of Chevron Corp. in San Ramon, Calif. A federal judge recently presided over lawsuits accusing big oil companies of lying about global warming. U.S. District Judge William Alsup asked lawyers for two California cities and five of the world's largest oil and gas companies to present "the best science now available on global warming." (AP Photo/Paul Sakuma, File)
FILE - In this Dec. 7, 2009, file photo, demonstrators block the main entrance of Chevron Corp. in San Ramon, Calif. A federal judge recently presided over lawsuits accusing big oil companies of lying about global warming. U.S. District Judge William Alsup asked lawyers for two California cities and five of the world's largest oil and gas companies to present "the best science now available on global warming." (AP Photo/Paul Sakuma, File)
FILE - In this Dec. 7, 2009, file photo, demonstrators block the main entrance of Chevron Corp. in San Ramon, Calif. A federal judge recently presided over lawsuits accusing big oil companies of lying about global warming. U.S. District Judge William Alsup asked lawyers for two California cities and five of the world's largest oil and gas companies to present "the best science now available on global warming." (AP Photo/Paul Sakuma, File)