Endangerment without consideration of regulatory consequences
EPA should explain whether it considered a finding that methane and the other four nonCO2 GHGs do in fact contribute to climate change, based on their higher warming potential, but that overriding policy concerns make such a finding infeasible concerning CO2. Because methane and the other four non-CO2 GHGs are either already regulated under the CAA or are functionally equivalent to pollutants typically regulated under the CAA, an endangerment finding for these GHGs would be relatively routine.
Because GHGs are understood to be long-lived, well-mixed in the atmosphere, and generated by many nations around the globe, the most analogous regulatory approach for controlling GHGs would seem to be Title VI of the CAA. EPA’s relevant experience with controlling ozone-depleting substances should inform its decisions on an approach to regulating GHGs.
In contrast, an endangerment finding under section 202 may not be not the most appropriate approach for regulating GHGs. Making the decision to regulate CO2 under the CAA for the first time is likely to have serious economic consequences for regulated entities throughout the U.S. economy, including small businesses and small communities. Should EPA later extend this finding to stationary sources, small businesses and institutions would be subject to costly regulatory programs such as New Source Review.