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Climate Change Hero

Climate Change Blog

  • 03
  • August
  • 2016


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Up in the Air: EPA Issues Aircraft GHG Endangerment Finding

On July 25, the U.S. Environmental Protection Agency (EPA) issued its endangerment and cause or contribute finding that six greenhouses gases (GHGs) (carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride) in the atmosphere endanger the public health and welfare and that GHG emissions from aircraft contribute to this air pollution. EPA first proposed the endangerment finding back in July 2015. The finding does not include GHG emission standards for the aircraft industry, and an additional rulemaking will be necessary before EPA can take steps to directly regulate GHG emissions from aircraft under Section 231 of the federal Clean Air Act (CAA). Sections 231 and 232 of the CAA require that the EPA and the Federal Aviation Administration coordinate on the implementation and enforcement of aircraft emissions standards. 

Why Aircraft?

EPA justifies the need for the finding based on the U.S. aircraft sector’s contribution to climate change and the lack of existing regulation with respect to GHG emissions from the sector. The agency has determined that U.S. aircraft account for 3% of U.S. GHG emissions and for 29% of GHG emissions from all aircraft globally. With respect to the U.S. transportation sector, U.S. aircraft account for 12% of the sector’s GHG emissions.

The driver for this endangerment finding can be traced to a December 2007 petition the EPA received requesting that the agency make an endangerment finding for aircraft GHGs and regulate those emissions under Section 231 of the Clean Air Act. The agency’s decision relies on the scientific evidence that served as the basis for its original motor vehicle GHG emissions endangerment finding in 2009. The finding also states that the EPA reviewed more recent climate change assessments by the National Research Council, the U.S. Global Change Research Program, and the Intergovernmental Panel on Climate Change, and found that those assessments only strengthened the conclusions of the science underlying the 2009 endangerment and cause or contribute finding.

Scope of Potential Regulation

The finding applies to “U.S. covered aircraft.” The rulemaking defines “U.S. covered aircraft” to be subsonic jet aircraft with a maximum takeoff mass (MTOM) greater than 5,700 kilograms and subsonic propeller driven aircraft (e.g., turboprops) with a MTOM greater than 8,618 kilograms. This definition matches international proposals for GHG emissions and essentially covers everything from certain small jets to jumbo passenger liners. EPA has determined that this category of aircraft covers approximately 89% of GHG emissions from all U.S. aircraft.

Subsonic jet aircraft with a MTOM greater than 5,700 kilograms

Subsonic propeller driven aircraft with a MTOM greater than 8,618 kilograms

What’s Next

Finalization of the endangerment finding now opens the door to direct regulation of aircraft GHG emissions by EPA. This issue, however, is not being addressed in a vacuum. The international community is also working to address GHG emissions from aircraft. Typically, the International Civil Aviation Organization (ICAO) of the United Nations first adopts international standards, and then EPA initiates a rulemaking under Section 231 of the CAA.

The ICAO has proposed a GHG emission standard that would reduce aircraft fuel consumption by 4% compared to 2016 levels in new commercial aircraft designed after 2020 and built after 2028. The standard also applies to aircraft currently in production delivered after 2023. In addition to the GHG standard, ICAO is working on a market-based offset mechanism to cap GHG emissions from the airline sector. The proposed cap and trade system, which ICAO hopes to finalize later this year, would cap GHG emissions from airlines at 2020 levels and thereafter require reductions or offsets for any emissions from international flights above that limit. Options for meeting the cap include fuel efficiency measures and the use of low-carbon fuels. Offsets would be purchased based on GHG reductions from outside the airline sector. However, agreement on the market-based measure appears stalled while countries attempt to resolve issues related to the treatment of developing nations versus developed nations under the cap.

Overall, the endangerment finding may not result in significant regulatory action by EPA, other than the final adoption of the international standards currently subject to debate. However, if the ICAO fails to take action, or, if EPA does not believe that international standards are protective enough, EPA could take steps under the CAA to promulgate its own aircraft GHG emissions standards. EPA could also seek a more aggressive implementation timetable than the one proposed by ICAO if the agency chooses to adopt the ICAO proposal. Gina McCarthy, EPA Administrator, has previously indicated that the agency views the proposed market-based mechanism as an important component to enhance what some critics have called a weak emissions standard.

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Mattew T. Dobbins

Matthew Dobbins Senior Associate