On December 11 at the Durban (South Africa) Conference on Climate Change, the world agreed to extend the Kyoto Protocol and begin negotiations on a new global treaty that will require all countries (developed and developing) to reduce their greenhouse gas emissions.
In a national survey completed in November 2011, we found that a large majority of Americans (66%) support signing an international treaty requiring the US to cut emissions 90% by 2050:

Breaking the result down by political party (among registered voters), we found that large majorities of Democrats (81%) and Independents support such a treaty (61%), while almost half of Republicans support such a treaty (49%).

Source: Public Support for Climate & Energy Policies in November 2011