In 2015, EPA issued an Advance Notice of Proposed Rulemaking that sought input on issues related to setting an international CO2 standard for aircraft, and the potential use of section 231 of the Clean Air Act to adopt a corresponding aircraft engine standard domestically. Also in 2015, under section 231(a) of the Clean Air Act, EPA proposed findings that GHG emissions from certain classes of engines used in aircraft contribute to the air pollution that causes climate change endangering public health and welfare. In 2016, EPA finalized these findings, which triggered a requirement for EPA to promulgate standards addressing GHG emissions from engines on covered aircraft. Read more about the endangerment finding here.
In 2021 EPA promulgated a rule to regulate GHGs from aircraft.
In California v. EPA, a group of twelve states and the District of Columbia are challenging the Jan. 11, 2021 rule in the D.C. Circuit. On February 17, 2021, the D.C. Circuit granted EPA’s motion to hold the cases challenging the greenhouse gas standards for aircraft in abeyance while EPA reviews the standards pursuant to Executive Order 13990. On November 15, 2021, the EPA filed a joint motion announcing that, since it has decided not to alter the Jan. 11, 2021 rule, all parties agree that the abeyance should be lifted and that the challenge should proceed on the merits.