Enacted in 1970, NEPA generally requires agencies to consider the environmental effects of proposed agency actions, and to provide the public and decision makers with useful information regarding reasonable alternatives and mitigation measures. To coordinate federal environmental efforts, NEPA also established CEQ within the Executive Office of the President. CEQ is now charged with issuing mandatory regulations for NEPA implementation, as well as guidance documents such as the recent greenhouse gas guidance.
In its final greenhouse gas guidance, CEQ described climate change as "a fundamental environmental issue" whose effects fall squarely within NEPA's purview. In CEQ's words, "Analyzing a proposed action’s GHG emissions and the effects of climate change relevant to a proposed action — particularly how climate change may change an action’s environmental effects — can provide useful information to decision makers and the public." CEQ views focused and effective consideration of climate change in NEPA reviews as enabling higher quality agency decisions.
To this end, CEQ offered guidance that:
when addressing climate change agencies should consider: (1) The potential effects of a proposed action on climate change as indicated by assessing GHG emissions (e.g., to include, where applicable, carbon sequestration); and, (2) The effects of climate change on a proposed action and its environmental impacts.The guidance presents further information and interpretation on each of these points. For example, it recommends that agencies quantify the direct and indirect greenhouse gas emission resulting from a proposed agency action, as well as both short- and long-term adverse and beneficial effects. The guidance also stated that "a NEPA review should consider an action in the context of the future state of the environment."
In one sense, the final guidance is just guidance. As CEQ noted, agencies have discretion in how they tailor their individual NEPA reviews to accommodate the guidance. CEQ directed that agencies should apply this guidance to all new proposed agency actions as of the initiation of NEPA review. It suggested that agencies "should exercise judgment" when considering the application of the guidance to an on-going NEPA process, but that CEQ does not expect agencies to apply the guidance to concluded NEPA reviews, nor to any actions for which a final Environmental Impact Statement (EIS) or Environmental Assessment (EA) has been issued.
CEQ recommended that agencies review their NEPA procedures and propose any updates they deem necessary or appropriate to facilitate their consideration of greenhouse gas emissions and climate change. Agency procedures to implement NEPA may be in the form of regulations, although they are not required to take that form. CEQ's final guidance on greenhouse gas emissions may lead other federal agencies to revise regulations, policies, or implementing procedures to ensure full compliance with NEPA.