U.S. Aircraft Greenhouse Gas Rulemaking Process

(Presented by the United States) 

SUMMARY

This information paper describes the rulemaking process in the United States 

to issue proposed endangerment and cause or contribute findings for the 

regulation of aircraft greenhouse gas emissions.

1. INTRODUCTION

1.1 The United States Environmental Protection Agency (U.S./EPA) and the U.S. Federal 

Aviation Administration (FAA) work within the ICAO/CAEP standard setting process to establish

international emission standards and related requirements. Under this approach international emission 

standards have first been adopted by ICAO, and subsequently U.S./EPA has initiated rulemakings to 

establish domestic standards equivalent to ICAO’s standards. In exercising U.S./EPA’s standard-setting 

and FAA’s enforcement authorities, the U.S. expects to follow a similar approach for aircraft greenhouse 

gas (GHG) emission standards (or aircraft CO2 standards). 

1.2 The U.S. anticipates that CAEP will adopt an aircraft CO2 emissions standard in 

February 2016, and in preparing for the subsequent U.S./EPA domestic rulemaking process to adopt

standards equivalent to the CAEP CO2 standards, U.S./EPA would first need to propose and then finalize 

endangerment and cause or contribute findings for aircraft GHG emissions. These findings, which are 

factual and science-based, are a determination of whether emissions cause or contribute to air pollution 

which may reasonably be anticipated to endanger public health or welfare. If a positive endangerment

and cause or contribute findings are made, U.S./EPA is obligated under the Clean Air Act (CAA) to set 

GHG emission standards for aircraft. 

1.3 It is also important to note that there are domestic pressures from stakeholders and court 

proceedings within the U.S. in regard to U.S./EPA adopting aircraft GHG standards. These items and the 

rulemaking process are described further below. 

2. DESCRIPTION OF PROPOSED AIRCRAFT GREENHOUSE GAS 

RULEMAKING PROCESS

2.1 The U.S./EPA is initiating the rulemaking process in response to a petition the U.S./EPA

received in December 2007, which requested that U.S./EPA make an endangerment finding for aircraft 

GHGs and regulate these emissions under §231 of the Clean Air Act (CAA). Petitioner filed a lawsuit in 

2010 on this matter, and the D.C. District Court in 2012 ruled that the CAA required U.S./EPA to make a 

final determination on whether aircraft GHG emissions cause or contribute to air pollution which may 

reasonably be anticipated to endanger public health or welfare. U.S./EPA is now moving forward to 

make a determination regarding aircraft GHG emissions. 
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2.2 In this action, U.S./EPA will determine whether greenhouse gas emissions from aircraft 

cause or contribute to air pollution which may reasonably be anticipated to endanger public health or 

welfare. The aircraft GHG endangerment finding proposal will build on U.S./EPA’s 2009 §202 CAA 

endangerment and cause or contribute findings for on-road vehicles and thus rely on previous peerreviewed science from the major climate change science assessments of the U.S. Global Change Research 

Program (USGCRP), National Research Council (NRC), and the Intergovernmental Panel on Climate 

Change (IPCC), along with updated reports from the same major climate change assessments. 

2.3 Concurrent with these proposed findings, U.S./EPA will release an Advanced Notice of 

Proposed Rulemaking (ANPRM) to provide an overview of ICAO/CAEP efforts to reduce greenhouse 

gas emissions. The ANPRM will include a discussion of ICAO’s progress in establishing global aircraft 

CO2 standards and, if U.S./EPA finds that aircraft GHG emissions do cause or contribute to air pollution

that endangers public health and/or welfare, the potential use of §231 of the CAA to implement these 

standards domestically will ensure transparency and the opportunity for public comment.

2.4 Under our current schedule, U.S./EPA would propose endangerment and cause/contribute 

findings and domestically release an ANPRM in late April 2015. Subsequently, it would take about 

another year to finalize the findings.

3. SUMMARY

3.1 U.S./EPA is now moving forward with a rulemaking process to propose endangerment 

and cause or contribute findings regarding aircraft GHG emissions. At the same time, U.S./EPA will 

issue an ANPRM to provide an overview of ICAO/CAEP efforts to set aircraft CO2 standards. Currently, 

the U.S. expects approval signature for the domestic release of the proposal/ANPRM in late April 2015.