The U.S. Department of Energy says the global output of carbon dioxide, a greenhouse gas that causes more heat to be trapped in the atmosphere, has soared to the largest amount on record — higher than the worst case scenario outlined by scientists from the U.N. Intergovernmental Panel on Climate Change just four years ago. The total amount of carbon pumped into the air globally jumped by 6 percent in 2010. One scientist described it as a “monster” increase. Pollution from China and the United States accounted for more than half the increase in emissions last year.