Which Government Policies and Other Factors Have Reduced U.S. Carbon Emissions?

The U.S. was the largest emitter carbon dioxide (CO2) until 2006 when China’s emissions exceeded the U.S.  U.S. CO2 emissions from the consumption of fossil fuels peaked in 2007 and have declined significantly over the past five years.  Refer to the following graph:

Data Source: EIA MER...Which Government Policies and Other Factors Have Reduced U.S. Carbon Emissions?