US carbon emissions began to plateau in 2005 to 2007. Since 2007, US carbon emissions have plummeted 13% and are back to 1994 levels. The drop is driven by the boom in gas, renewables, and efficiency.
Or is the sharp drop driven by the near depression from 2007 to 2009? The answer is no. US GDP resumed growth, starting July 1, 2009. The US economy measured by GDP was bigger in 2012 than in 2007, 2005, and 1994. Our population was too.
The 13% decline in carbon emissions is not the product of a smaller economy or population but the result of zero or lower carbon fuels gaining market share and growing energy efficiency. Starting in 2007, simultaneous booms in natural gas production as well as wind and solar power commenced and reached impressive scale by 2012. Those booms combined with drops in total US energy consumption produce a 13% decline in carbon emissions.