The Environmental Integrity Project released its report U.S. Power Plant Global Warming Emissions Rising in 2013, After Years of Decline on May 23, finding that first quarter 2013 carbon dioxide emissions are 7.14 percent higher than levels reported a year ago. The report linked the rise to an increase in natural gas prices, which has made coal more competitive. Coal-fired power plants were found to have a 13 percent emissions increase from the first quarter of 2012 to the first quarter of 2013.