Global carbon dioxide emissions grew last year at about half the rate of the past decade, possibly signaling a permanent slowdown of CO2 emissions, says a new report from the Netherlands Environment Assessment Agency and the European Commission’s Joint Research Center. Although total CO2 emissions reached a record 34.5 billion tons, the increase over 2011 was only 1.1 percent — less than half the average rate of increase over the past decade. China, the U.S., and the European Union accounted for 55 percent of global CO2 emissions. China, which emitted 29 percent of total CO2, increased its rate by only 3 percent, a significant slowdown from its average recent growth of 10 percent. The analysts credit the slowdown to China’s rapid growth in hydropower. The U.S. and European Union saw their emissions fall by 4 percent and 1.6 percent, respectively. The report links those declines to increased shale gas use in the U.S. and decreased energy consumption and freight transport in the E.U. Globally, the pace of renewable energy growth has been accelerating, the report said.