President Hu Jintao , Chinese leader pledge to work to reduce carbon emissions . Move comes before Climate Change Conference . Climate Change Conference in Denmark . China and Denmark are largest producers of greenhouse gases . After Tuesday 's meeting , Hu told reporters , `` We agreed to expand our cooperation on climate change , energy and environment , '' which includes developing a China-U.S. clean energy research center . Obama , Chinese President Obama do n't offer a timetable .
President Hu Jintao , Chinese leader pledge to work to reduce carbon emissions . Move comes before Climate Change Conference . Climate Change Conference in Denmark . China and Denmark are largest producers of greenhouse gases . Obama , Chinese President Obama do n't offer a timetable .