Obama, Xi lay out joint vision for global climate agreement

By Valerie Volcovici WASHINGTON (Reuters) - U.S. President Barack Obama and Chinese President Xi Jinping outlined their common vision for a global climate change agreement on Friday, including new steps they will take to deliver on pledges made last year to slash their greenhouse gas emissions. Such systems put limits on carbon emissions and open up markets for companies to buy and sell the right to produce emissions. The joint presidential statement was a highlight of a state visit to Washingto