Lead U.S. climate negotiator Todd Stern said Thursday the Copenhagen Accord represents the best way forward for a binding global climate deal but that success likely rests with a smaller group of major emitters working outside the unwieldy, multi-national United Nations process.In his first public remarks since the conclusion of the United Nations climate talks in December, Stern said the Copenhagen Accord - despite its shortcomings - included "significant breakthroughs in a number of respects.