President Obama , Chinese leader pledge to work to reduce carbon emissions . Move comes before referendum . Climate Change Conference in Denmark . China and Denmark are largest producers of greenhouse gases . Obama , Chinese President Hu ##an do n't have a timetable .
President Obama , Chinese leader pledge to work to reduce carbon emissions . Move comes before U.N . Climate Change Conference in Denmark . China and U.S. are largest producers of greenhouse gases . Obama , Chinese President Hu Jintao do n't offer a timetable .