"We did this review to evaluate the extent to which the U.S. Environmental Protection Agency's (EPA's) Greenhouse Gas (GHG) voluntary programs can significantly reduce future GHG emissions, and whether their data is complete and reliable. [...] Concerns about human-caused global warming and the potential impacts of GHG emissions were first raised in the 1960s. In 1992, the United States signed and Congress ratified the United Nations Framework Convention on Climate Change Treaty in Rio de Janeiro. The 'Rio' Treaty requires the United States to implement programs to reduce GHG emissions. The United States decided to achieve this goal through implementing voluntary programs."
Environmental Protection Agency, Office of the Inspector General: 08-P-0206
U.S. Environmental Protection Agency: http://www.epa.gov/