Reuters: World powers are running out of time to slash their use of high-polluting fossil fuels and stay below agreed limits on global warming, a draft U.N. study to be approved this week shows. Government officials and top climate scientists will meet in Berlin from April 7-12 to review the 29-page draft that also estimates the needed shift to low-carbon energies would cost between two and six percent of world output by 2050. It says nations will have to impose drastic curbs on their still rising greenhouse...