Earlier this month, the Environmental Protection Agency (EPA) took the next step to regulate greenhouse gas (GHG) emissions from aircraft by determining that certain engine pollutants pose a danger to human health and the environment, and are contributing to climate change. In its proposed rule, EPA found that carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride emissions from aircraft should be regulated under the Clean Air Act. The rule does not propose emissions standards at this time, it only represents the first step in the required rulemaking process, a process that could take many years to be completed.

According to EPA’s announcement of the proposed rule, aircraft emissions are the largest GHG-emitting transportation source not already regulated under current U.S. law. U.S. aircraft emit approximately 11% of GHG emissions from the transportation sector domestically, 3% of total U.S. GHG emissions, 29% of GHG emissions from all aircraft globally, and 0.5% of total global GHG emissions.

The proposed scope of covered aircraft engines would include smaller aircraft such as the Cessna Citation CJ2+ and the Embraer E170 and up to the largest aircraft – the Airbus A380 and the Boeing 747. The rule would not include military or smaller aircraft such as turboprops, smaller jet aircraft, piston-engine aircraft, and helicopters. 

EPA has indicated that the carbon dioxide standards currently being established by the International Civil Aviation Organization (ICAO) may influence the agency’s regulations. ICAO’s emissions standards for carbon dioxide are expected to be adopted in early 2016.

As discussed in this blog, this rulemaking is the result of years of citizens administrative petitions and lawsuits by environmental groups. Interested parties are encouraged to submit comments on the proposed rule, which are due 60 days beginning when the proposed rule is published in the Federal Register. The rule should be published in early July. Instructions for filing comments can be found on EPA's website.