The early feedback on the framework coming out of Warsaw:
2015 marks the deadline for a multilateral agreement under the UNFCCC that will be a) replace the Kyoto Protocol and b) be implemented no later than 2020. It was decided back in Durban (COP17) that a new legal agreement was needed in which all countries play a role in reducing greenhouse gases and adapting to a new climate.
From the UNFCCC:
This includes work to make existing national emission reduction or emission limitation plans more transparent. It also encompasses the launch and long-term implementation of the comprehensive global support network that will deliver funding and technology to help developing countries build their own clean energy futures and construct societies and economies which are resilient to climate change. (emphasis added)
As one of the largest national greenhouse gas emitters, the U.S. needs to both significantly and deliberately reduce its emissions (not just show up at the international negotiations table) and Congress will need to ratify any final treaty that comes out of the UNFCCC process by 2015. Given the current "climate" in Washington D.C., that seems more difficult than reaching compromise and agreement on the international stage.