Fortune 500 companies including General Electric Co., Duke Energy Corp. and JPMorgan Chase & Co. in recent months have championed stronger government measures to reduce industrial releases of carbon dioxide...This shift in corporate thinking was on display at a congressional hearing last week, where executives from large companies including DuPont Co., United Technologies Corp. and Baxter International Inc. described how they were getting an early start on reducing greenhouse gas emissions -- something they believe they would be required to do sooner or later..."We think the science is pretty compelling, and it is appropriate to take action now" to reduce global warming, said Helen Howes, vice president for environment, health and safety at Exelon Corp., one of the nation's largest utilities...[also refers to Cinergy, Citigroup, Bank of America]