Reuters: Global warming activist Al Gore on Friday urged passage this year of a U.S. law to slash greenhouse emissions, saying failure to pass legislation could cause the collapse of world climate negotiations. Gore, the former U.S. vice president and star of the Oscar-winning documentary film “An Inconvenient Truth,” told members of the House Energy and Commerce Committee that passing a climate law is a “moral imperative” that will affect U.S. standing in the world community. “Once we …