The letter to 300-plus companies and groups is among the first actions of the Bicameral Task Force on Climate Change that Democrats unveiled last week.

Recipients of the letter include oil and power companies such as Exxon and Southern Co., think tanks, environmentalists, defense contractors, retailers like Wal-Mart, financial companies like Goldman Sachs, food companies and many other sectors.

Also on the list: the National Football League, the National Basketball Association and other sports leagues.