"Washington, DC - July 7, 2009 -- United States Senator Mike Crapo (Republican of Idaho) listens to the testimony during the U.S. Senate Committee on Environment and Public Works hearing entitled, ""Moving America toward a Clean Energy Economy and Reducing Global Warming Pollution: Legislative Tools."" in Washington, D.C. on Tuesday, July 7, 2009. The legislation being considered is known as a cap-and-trade bill that would place mandatory limits on the emissions of the greenhouse gases that are said to cause global warming..Credit: Ron Sachs / CNP"