In December 2009, EPA ruled that climate change caused by emissions of greenhouse gases threatens the public's health and the environment. Since that time, EPA has received ten petitions challenging their determination. On July 29, 2010, EPA announced that it has denied these petitions.

The petitions to reconsider EPA's "Endangerment Finding" claimed that climate science can't be trusted, and asserted a conspiracy that calls into question the findings of the Intergovernment Panel on Climate Change, the U.S. National Academy of Sciences, and the U.S. Global Change Research Program. The EPA seriously considered these petitions, however, found no evidence to support the claims, and has denied them.  For further information, see:http://www.epa.gov/climatechange/endangerment/petitions.html.