Carbon dioxide emissions from burning fossil fuels in the United States peaked at more than 1.6 billion tons of carbon in 2007. Since then they have fallen 11 percent, dropping to over 1.4 billion tons in 2013, according to estimates from the U.S. Energy Information Administration. Emissions shrank rapidly during the recession, then bounced back slightly as the economy recovered. But shifting market conditions, pollution regulations, and changing behaviors are also behind the decline.
Oil is the largest source of carbon emissions in the United States. After a steep drop following the 1979 oil crisis, emissions from oil climbed steadily until 2005, when they peaked at 715 million tons of carbon. Since then, these emissions have fallen by 14 percent, or 101 million tons of carbon