Guardian: The next few weeks will be critical in deciding whether the Copenhagen accord succeeds in halting global warming, America’s top climate change envoy said today. “We have an accord that is lumbering down the runway, and we need it to get enough speed so it can take off,” Todd Stern, the state department climate change envoy, told an investor meeting at the United Nations in his first public remarks after the Copenhagen summit. “We need to get this up and running.” He said the …