Al Gore, former U.S. vice president, on Wednesday took his campaign against global warming to Capitol Hill, stressing the need for quick action.

Fresh off a triumphant Hollywood appearance in which his climate-change documentary, "An Inconvenient Truth," won two Oscars, Gore drew overflow crowds as he testified before a joint panel, terming the current climate crisis: "Our world faces a true planetary emergency."

Gore discussed the risks of sea level rise, stronger storms, more wildfires and other ills associated with global climate change, and urged an immediate freeze on U.S. carbon dioxide emissions.

    At the House hearing, he was flanked by cardboard boxes that he said contained some 516,000 letters calling for congressional action to stop global warming.

    "This problem is burning a hole at the top of the world in the ice cover that is one of the principle ways our planet cools itself," Gore said. "If it goes, it won't come back on any timescale relevant to the human species."