by Chip Knappenberger February 11, 2010 Back in December, the EPA announced that it had determined that greenhouse gases released by human activities “threaten the public health and welfare of current and future generations.” This “Endangerment Finding” is the first step toward EPA’s issuing regulations aimed at restricting GHG emissions in the U.S. Unfortunately for the EPA, a major pillar of support of the Endangerment Finding—that “most” of the “observed warming” since the mid-20th century is from greenhouse gas emissions from human activities—has been shown by recent scientific research in major peer-reviewed scientific journals to be largely in doubt. Add this result to the list of problems that seems to grow longer with each passing day as more IPCC gaffes are uncovered and Climategate emails are parsed. One has to wonder just how long it will be until the EPA is challenged to reconsider its Endangerment Finding. The basis for the Engangerment Finding is contained in the EPA’s Technical Support Document for Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act (TSD). The TSD does not describe any new, independent research carried out by the EPA (because they did not undertake any), but instead largely summarizes the findings of the Intergovernmental Panel on Climate Change (IPCC).