A single airplane flies across a deep blue sky, leaving behind a trail.

Aircraft Emissions

Aviation emissions are a significant source of the world’s total greenhouse gas emissions, and the airline industry in the United States is the single largest emitter of aviation emissions. Globally, the aviation industry is responsible for approximately 2.4 percent of all carbon dioxide emissions and 12 percent of greenhouse gas emissions from all transportation sources. The United States contributes more than a quarter of global aviation greenhouse gas emissions, and its emissions from aircraft alone are higher than total greenhouse gas emissions in more than 150 countries. Greenhouse gas emissions from U.S. aircraft are expected to grow 43 percent in the next two decades, and globally, aviation emissions are expected to triple by 2050.

Greenhouse Gas Emissions from Aircraft


  • January 2021

    In January 2021, at the end of the Trump administration, the EPA finalized its rule to regulate greenhouse gas emissions from aircrafts, ignoring the recommendation of attorneys general to set regulations that would result in actual reductions in emissions.

    Later in January 2021, a coalition of 13 states led by California Attorney General Becerra filed a petition for review challenging the decision as unlawful and requesting the rule be remanded to the EPA. As of June 2021, the litigation was in abeyance.

  • February 2022

    In February 2022, a coalition of 13 states, led by California Attorney General Rob Bonta filed a challenge to EPA’s GHG emissions rule for aircraft. State of California, et al v. EPA, No. 21-1018 (D.C. Cir). The AGs argued that EPA should have promulgated more stringent standards than those set by the International Civil Aviation Organization (ICAO). The AGs also argued that EPA acted unlawfully, arbitrarily, and capriciously by aligning domestic standards with ICAO’s technology-following standards, rather than establishing technology-forcing standards.

  • October 2022

    In October 2022, the U.S. Court of Appeals for the D.C. Circuit heard oral arguments.

  • June 2023

    In June 2023, the court denied the AGs’ petition. It held that the Aircraft Rule is within EPA’s authority under section 231 of the Clean Air Act. It also found that EPA reasonably explained its decision to harmonize domestic regulation with the International Civil Aviation Organization’s (ICAO) standards.


  • August 2020

    In August 2020, the EPA published a proposed rule setting hollow greenhouse gas emissions standards for airplanes that would result in no actual reduction in emissions. The EPA’s proposal mirrors a set of standards developed by the International Civil Aviation Organization in 2016, which were set to such a low stringency level that all aircraft currently in development or in production would already comply.

  • October 2020

    In October 2020, a coalition of 12 attorneys general led by California Attorney General Xavier Becerra submitted comments in opposition to the EPA’s proposal. The coalition emphasized that the EPA’s failure to even consider feasible reductions in greenhouse gas emissions violates the Clean Air Act and is arbitrary and capricious. The attorneys general also pointed out that their states have made significant efforts to address aviation’s climate impacts by reducing and offsetting greenhouse gas emissions from airports, but are preempted under the Clean Air Act from establishing their own emissions standards for aircraft. States therefore rely on the EPA to adopt federal standards in order to protect the health and welfare of their residents and avoid damage to their economies. The coalition urged the EPA to rescind the proposal and instead consider the full range of feasible options for effective emissions control and propose standards that actually reduce dangerous greenhouse gases from aircraft.

Particulate Matter Emissions from Aircraft


  • February 2022

    In February 2022, EPA proposed a rule rule on particulate matter (PM) emission standards and test procedures for certain classes of aircraft engines. Particulate matter consists of very small liquid or solid particles that pollute the air and have a range of negative health effects. The proposed rule declined to require any reductions.

  • April 2022

    In April 2022, a coalition of 12 states led by California Attorney General Rob Bonta submitted comments on that proposal. The AGs argued that EPA did not adequately acknowledge the burden of PM emissions from airplanes on nearby communities that are already overburdened by pollution.

  • November 2022

    In November 2022, the EPA published its final rule. The rule would go into effect December 2022.

  • January 2023

    In January, a coalition of 11 states led by California Attorney General Rob Bonta filed a petition for review challenging the rule. A different challenge is already pending in the U.S. Court of Appeals for the D.C. Circuit regarding EPA’s similar regulation of greenhouse emissions from aircraft and the fate of this new case will likely hinge on how that case is resolved.

  • August 2023

    In August 2023, the same coalition of 11 states, along with multiple nonprofit organizations who had filed separate petitions for review, filed a joint motion to dismiss their petitions. Previously, the case had been held in abeyance pending the outcome of State of California, et al v. EPA, No. 21-1018 (D.C. Cir), because both cases involved the same parties, arguments, and questions of law.