Conclusion: Greenhouse gases threaten human health and the environment

Or perhaps more precisely, a foregone conclusion?

As announced on December 7 (UPDATE: and published on December 15 in the Federal Register), the US Environmental Protection Agency administrator has signed two findings on greenhouse gases under the Clean Air Act:

  • Endangerment: That current and projected concentrations of the six key greenhouse gases – carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) – in the atmosphere threaten the public health and welfare of current and future generations; and
  • Cause or Contribute: That the combined emissions of these well-mixed greenhouse gases from new motor vehicles and new motor vehicle engines contribute to the greenhouse gas pollution which threatens public health and welfare.

These determinations are prerequisite for EPA to finalize its greenhouse gas emissions limitations for light-duty vehicles, including passenger automobiles, proposed in September.

Unless you have not been paying attention to the news on climate change issues, you might also know that the endangerment finding also paves the way for regulatory control of greenhouse gas emissions from stationary sources. In lieu of the uncertain “cap and trade” legislation, EPA can begin to regulate GHGs through the administrative rulemaking process, and has signalled its intent to apply regulatory controls to power plants and other large emitters of GHGs, as noted here on October 13.

For more information on regulatory implications of greenhouse gases and climate change, visit our web page at