On June 10, 2015, the US Environmental Protection Agency (EPA) Administrator proposed to find that greenhouse gas (GHG) emissions from certain classes of engines used in aircraft contribute to the air pollution that causes climate change and that endangers public health and welfare under section 231(a) of the Clean Air Act. Notably, the EPA is not proposing aircraft engine GHG emission standards at this time.

The EPA also issued an Advance Notice of Proposed Rulemaking that provides information on the process for setting an international CO2 emissions standard for aircraft at the International Civil Aviation Organization. The proposed rulemaking describes, and seeks input on, the potential use of section 231 of the Clean Air Act to adopt and implement the corresponding international aircraft engine CO2 emissions standard domestically.

The US transportation sector is a significant contributor to total US and global anthropogenic GHG emissions. Aircraft remain the single largest GHG-emitting transportation source not yet subject to GHG standards in the United States.

US aircraft emit:

  • 11 percent of GHG emissions from the transportation sector in the United States.
  • 3 percent of total US GHG emissions.
  • 29 percent of GHG emissions from all aircraft globally.
  • 0.5 percent of total global GHG emissions.

Further details regarding the contentious history (including litigation) preceding today’s proposed finding and rulemaking is available on the related EPA Aviation webpage.