In June 1992, the United States signed, and later ratified in October, the United Nations Framework Convention on Climate Change (UNFCCC). Pursuant to the national communication reporting requirements under Articles 4.2 and 12 of the Convention and to guidelines later adopted by the UNFCCC Conference of the Parties (COP), the United States submitted the first U.S. Climate Action Report (USCAR) to the UNFCCC Secretariat in 1994, the second in 1997, and the third in 2002. The draft of the fourth report was available on this site from May 4 through June 1, 2007 to allow the public to comment on the draft text of the national communication before the final document was completed. The final report was submitted July 27, 2007. he fourth CAR provides an update on key activities conducted by the U.S. since the third CAR, an inventory of U.S. greenhouse gas emissions and sinks, an estimate of the effects of mitigation measures and policies on future emissions levels, and a description of U.S. leadership and involvement in international programs, including associated contributions and funding efforts. In addition, the text discusses U.S. national circumstances that affect U.S. vulnerability and responses to climate change. Finally, the CAR presents information on the U.S. Climate Change Science Program, the U.S. Climate Change Technology Program, our efforts in systematic observations, including the U.S. Integrated Earth Observation System, and our education, training and outreach efforts. The report takes into account activities up to and including 2006.