The United States has formally notified the United Nations that it embraced the Copenhagen Accord and would cut its carbon emissions 17 percent by 2020 from 2005 levels.<br/> In a letter to the Secretariat of the UN Framework Convention on Climate Change (UNFCCC), US Special Envoy for Climate Change Todd Stern yesterday, however, said that the U.S. move is conditional on other industrialized nations and large emerging economies following through with the deal reached in Copenhagen. He said, the US expect that all major economies will honor their agreement in Copenhagen to submit their mitigation targets or actions. The letter reaffirmed the promise U.S. President Barack Obama made to the UN Climate Change Conference held last month to cut U.S. emissions, saying that the 2020 commitment was a first step towards cutting America's global warming pollution by 42 percent in 2030, and by more than 80 percent by 2050.<br/>