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The EPA issued its proposed findings under section 231(a) of the Clean Air Act (CAA) on July 1, 2015 (80 FR 37757) that aircraft greenhouse gas (GHG) emissions cause or contribute to air pollution which may reasonably be anticipated to endanger public health and welfare. This action will finalize the proposed findings and respond to public comments. If finalized, the findings are scientific determinations under section 231(a) of the Clean Air Act; the EPA is not planning at this time to propose or issue aircraft engine GHG emission standards. This action continues to rely on the peer-reviewed science from the major climate change science assessments of the U.S. Global Change Research Program (USGCRP), National Research Council (NRC), and the Intergovernmental Panel on Climate Change (IPCC) underlying the 2009 endangerment and cause or contribute findings for GHGs under section 202 of the CAA, along with updated reports from the same major climate change assessments.

Statement of Need:

This action makes a determination regarding the current and future threat of climate change to public health and welfare. This action comes in response to a citizen petition submitted by Friends of the Earth, Oceana, the Center for Biological Diversity, and Earthjustice requesting that the EPA issue a GHG endangerment finding and standards under section 231(a)(2)(A) of the Act for GHG emissions from aircraft engines. Further, the EPA anticipates that the International Civil Aviation Organization (ICAO) will adopt a final international aircraft carbon dioxide (CO2) emissions standard in February 2016. The outcome of the final aircraft GHG endangerment and cause or contribute findings is a pre-requisite for the subsequent domestic rulemaking process.

Summary of the Legal Basis:

Section 231(a)(2)(A) of the CAA states that ‘‘The Administrator shall, from time to time, issue proposed emission standards applicable to the emission of any air pollutant from any class or classes of aircraft engines which in [her] judgment causes, or contributes to, air pollution which may reasonably be anticipated to endanger public health or welfare.’’ Before the Administrator may issue standards addressing emissions of GHGs under section 231, the Administrator must satisfy a two-step test. First, the Administrator must decide whether, in her judgment, the air pollution under consideration may reasonably be anticipated to endanger public health or welfare. Second, the Administrator must decide whether, in her judgment, emissions of an air pollutant from certain classes of aircraft engines cause or contribute to this air pollution. If the Administrator answers both questions in the affirmative, she must issue standards under section 231. See Massachusetts v. EPA, 549 U.S. 497, 533 (2007) (interpreting analogous provision in CAA section 202).

Alternatives:

This section is not applicable, as this action is a scientific determination and does not create any regulatory standards under section 231(a)(2)(A) of the CAA.

Anticipated Costs and Benefits:

This section is not applicable, as this action is a scientific determination and does not create any regulatory standards under section 231(a)(2)(A) of the CAA.

Risks:

The risks discussed here are the current and future threat of climate change to public health and welfare, relying on the scientific and technical evidence in the record for the 2009 section 202 CAA endangerment and cause or contribute findings and building on it with more recent major scientific assessments.