Both Barack Obama and Nancy Pelosi wanted to force the U.S. economy to a regulated 'cap and trade' straitjacket policy for CO2 emissions. This was the failed scheme that Australia and the EU actively pursued, and the U.S Democrats wanted to mimic.
The American public, and most Republicans, wanted nothing to do with 'cap & trade' straitjacket regulations, but instead desired a free market approach to reducing CO2 emissions.
And, as it now turns out, the American public and Republicans were a lot smarter than Obama, Pelosi and the incredibly dull leaders of Australia and the EU. Since 2006, the U.S. has led the world in reducing CO2 emissions and did it without bureaucratic mandates that politicians across the globe love.
Conclusion: The amazing and flexible free market in the U.S. has been responsible for the impressive and global-leading CO2 reductions, not the U.S. government and its stifling bureaucracy.
Hey, with that said about the wrong-way Democrats, Nancy sure does look great though, eh?