On July 29, 2010 the EPA re-affirmed its 2009 determination that climate change is real, is occurring due to emissions of greenhouse gases from human activities, and threatens human health and the environment by rejecting 10 petitions for reconsideration.

The petitions raised questions about the validity of the data relied on by the EPA in light of emails released to the public by hackers. The emails, from scientists at a climate-research center at Britain’s University of East Anglia, seemed to show climate scientists discussing problems with their own data, and scheming to silence their critics. The EPA cited several investigations that have cleared the researchers involved, and found that the emails revealed only “a candid discussion of scientists.”

The EPA did concede that errors had been found in a landmark United Nations report on climate change relied on by the EPA, but determined that none of the errors raised doubts about the overall direction of climate science. The EPA claims its “review shows that climate science is credible, compelling, and growing stronger.”

The 2009 “endangerment finding” paves the way for the agency to begin regulating greenhouse gases as harmful air pollutants under the Clean Air Act.

(This post was authored by Hamilton consulting Group’s intern, Emily Kelchen, a third year law student at the University of Wisconsin Law School.)