"The main aim of the Kyoto Protocol is to contain emissions of the main anthropogenic (i.e., human-emitted) greenhouse gases (GHGs) in ways that reflect underlying national differences in GHG emissions, wealth, and capacity to make the reductions" - wikipedia
The United States has signed the Kyoto Protocol but there is no intention to ratify the protocol.
It is painfully obvious that climate change is anthropogenic. The most recent study* funded by the Koch brothers show the effect of humans and carbon dioxide concentration on the surface temperature of Earth.
As Earth's primary polluter I believe that America should pave the way to a greener future.
*Koch funded study - http://berkeleyearth.org/results-summary/