02/25/2021 - Legal Analysis - Student Work

EPA’s New Aviation Emissions Standard: Why It’s Already Obsolete

by Sungjoo Ahn, JD 2021

Aviation is responsible for 3.5% of anthropogenic climate change. Until this year, however, the United States lacked any regulation addressing greenhouse gas (GHG) emissions from aircraft. In the final days of the Trump administration, EPA issued the first-ever aviation GHG emission standard, thus fulfilling its Clean Air Act (CAA) obligation to propose emission standards for pollutants found to cause or contribute to harmful air pollution.[1] However, EPA itself has projected that the new standard will not result in any emission reductions. In addition to environmental groups challenging the rule in federal court, the Biden administration issued an Executive Order on January 20 directing EPA to review the final rule. Going forward, both domestic regulation and foreign policy avenues are available for the Biden administration to address aviation emissions more effectively.


On January 11, 2021, the Environmental Protection Agency (EPA) issued a greenhouse gas (GHG) emissions standard for aircraft for the first time in US history. The rule explicitly adopts the carbon dioxide (CO2) emissions standards set in 2017 by the International Civil Aviation Organization (ICAO), the United Nations’ aviation authority that acts as a global forum for developing and adopting international aviation standards. The rule applies to civil subsonic jet airplanes and larger civil subsonic propeller-driven airplanes designed after January 2020, or in production by 2028.

Yet, critics as well as EPA predict that the final rule will not result in any emission reductions. Because the ICAO standards were based on technological feasibility, manufacturers had already developed or were developing technologies to bring the affected airplanes into compliance at the time the standards were adopted. In fact, the average new aircraft delivered in 2016, the year that ICAO standards were finalized, already complied with the 2028 requirements. Shortly after EPA proposed the rule, attorneys general from 11 states and Washington, DC submitted comments stating that EPA’s “failure to even consider” feasible GHG reductions is “unlawful and arbitrary.” The Center for Biological Diversity and other environmental groups also filed suit in the DC Circuit challenging the final rule.

Prior to the new rule, the US did not regulate GHG emissions from aviation at all—in part because the international aviation sector was omitted from both the Kyoto Protocol and the Paris Agreement. In July 2020, however, EPA identified two reasons for proposing a rule for aviation emissions. First, by adopting the ICAO standards into US law, US civil manufacturers will avoid being forced to seek emissions certification from a foreign aviation certification authority before marketing and operating their airplanes internationally. Second, in 2016, EPA made a finding under Section 231 of the CAA that GHG emissions from certain classes of aircraft engines endanger public health and welfare by contributing to climate-changing air pollution. This finding triggered Section 231(a)(2)(A) of the act, obligating the agency to set GHG standards for the covered aircraft engines.[2] Federal action to address aviation emissions is critical because the CAA preempts states from establishing their own aviation emission standards.[3] By adopting a rule that is already obsolete, EPA wastes a crucial opportunity—and neglects its statutory obligation—to establish a rule that will reduce aviation’s impact on public health and welfare.


ICAO’s emissions standards are complemented by a more progressive carbon offsetting agreement, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). Adopted in 2016 with commitments from 85 countries including the US, CORSIA provides a framework for a carbon offsetting market for international aviation, designed to achieve carbon-neutral growth after 2020. The voluntary pilot phase is scheduled to start in 2021, and the mandatory phase is scheduled for 2027-2035.

However, the impact of COVID-19 on the aviation industry has led ICAO to reassess this strategy. Because the original scheme would have used the average of 2019 and 2020 emissions data to calculate the CORSIA baseline, the ICAO Council expects that last year’s sharp and unexpected reduction in air travel would “disrespect the originally-agreed intention and objectives” of the member states. As a result, ICAO decided to use only the 2019 numbers, increasing the baseline by approximately 33% as compared to the 2019 and 2020 average. Applying pre-pandemic numbers in a post-pandemic reality would effectively render CORSIA meaningless. Because demand for international travel is not estimated to return to pre-pandemic levels for at least four years, the aviation sector will be able to meet CORISA’s offset obligations without introducing any changes to their existing practice. The reduced impact of CORSIA thus increases the need for effective federal GHG emissions standards.

EPA’s Broad Authority to Regulate Aviation Emissions

While the rule is EPA’s first attempt at regulating GHG emissions from aviation, the agency has regulated both non-GHG pollutants from aviation as well as GHG emissions from other mobile sources. Section 231(a)(2)(A) of the Clean Air Act grants EPA broad regulatory authority over aviation emissions, stating 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 his judgment causes, or contributes to, air pollution which may reasonably be anticipated to endanger public health or welfare.” The agency has used this power to regulate pollutants such as smoke, hydrocarbons, and carbon monoxide, albeit conservatively: these regulations were no more stringent than the lax international standards set by ICAO, and did not cover GHGs and other pollutants that were not already subject to international standards at the time.

EPA’s regulatory history for cars, trucks, and other vehicles is more robust. These mobile sources, along with aircraft, are covered under Title II of the CAA. Since the Supreme Court’s ruling in Massachusetts v. EPA[4] brought GHGs under the regulatory framework of the CAA, EPA and the National Highway Traffic Safety Administration (NHTSA) have jointly developed the national program for GHG and fuel economy standards. The program gradually increased the standards by phases, with Phase 1 running from 2012 to 2016 and Phase 2 from 2017 and 2025. While the Trump administration finalized a rule in April 2020 to loosen those standards for passenger cars and light trucks for model years 2021 through 2026, the Obama-era standards provide an example of how EPA could issue a phased regulatory standard to progressively decrease GHG emissions from the aviation sector.

(For more information on these rules, and related regulatory rollbacks under the Trump Administration, visit EELP’s Clean Car Rules page here).

Next Steps for the Biden Administration

On January 20, 2021, President Biden signed the “Executive Order on Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis.” The order reiterates the US commitment to safeguarding public health and promoting environmental justice, and directs executive departments and agencies to immediately review federal regulations from the Trump administration that conflict with those objectives. EPA’s final rule on aviation emissions was explicitly listed as one of the rules to review in accordance with the Executive Order, signaling that the administration will likely rescind, suspend, or replace the rule.

In its review of the EPA rule, the Biden administration can consider a progressive framework of regulation that becomes increasingly stringent over the years, similar to the fuel economy standards for motor vehicles. A comprehensive technology assessment by the International Council on Clean Transportation (ICCT) found that the rate of fuel burn improvement for new aircraft could be accelerated up to 2.2% annually through 2034 if cost-effective technologies were adopted. The administration may also consider standards that apply to both in-service aircraft and new aircraft in order to accelerate GHG emissions reductions sector-wide.

Aviation is also explicitly mentioned in a subsequent Executive Order on “Tackling the Climate Crisis at Home and Abroad” as a foreign policy area where the US will press for enhanced climate ambition. The order places climate change “at the center of United States foreign policy and national security” and commits to international multilateral and bilateral channels to address GHG emissions. There are opportunities for targeted bilateral diplomacy between the US and the EU, given that Boeing (based in the US) and Airbus (based in the Netherlands) together make up 91% of the global airplane manufacturing market. So far both Airbus and Boeing have committed to the modest goal of achieving carbon-neutral growth from 2020 onwards, and to adhering to the CORSIA standard of reducing CO2 emissions to 50% of 2005 levels by 2050. The Biden administration will likely pursue these diplomatic efforts in conjunction with, or as an alternative to, federal rulemaking.

Aviation is responsible for 3.5% of global anthropogenic climate change. In particular, aviation GHG emissions from the US alone rank higher than the national total GHG emissions of more than 150 countries. To meet its commitment to a net-zero economy by 2050, the Biden administration must address aviation emissions in one form or another and establish standards that do more than simply maintain the status quo.

[1] See 42 U.S.C. 7571(a)(2)(A)

[2] See 42 U.S.C. 7571(a)(2)(A).

[3] See 42 U.S.C. § 7573.

[4] 549 U.S. 497 (2007)