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January 31, 2025
In 2022, aircraft generated 9% of the nation’s transportation sector greenhouse gases and approximately 2.5% of all U.S. GHG emissions. At a global level, the International Energy Agency reports that aviation accounted for 2.5% of the world’s energy-related carbon dioxide emissions in 2023. According to the international industry trade organization Air Transport Action Group (ATAG), the sector produced 12% of all global transportation emissions.
Environmental Impacts of Aviation
Federal Aviation Administration summary of aviation’s environmental impact. Credit: FAA
The severe contraction in commercial aviation caused by the COVID-19 pandemic produced a major reduction in fuel consumption and carbon dioxide emissions by the industry. But after declining 46% in 2020, fuel consumption increased an average of 21% annually from 2021 through 2023. The International Air Transport Association (IATA) estimates global fuel consumption exceeded pre-pandemic levels in 2024. ATAG projects that with today’s fleet technology (i.e., using conventional fossil-based jet fuel and current operational efficiency), passenger air traffic would generate two billion tons of carbon dioxide annually in 2050, more than double the industry’s 2019 emissions.
Faced with these grim forecasts, ATAG, which includes Airlines for America (A4A), a trade association representing all the major U.S. carriers, saw the need to align the industry with global greenhouse gas emission reduction goals. In October 2021, ATAG announced a goal to achieve net-zero carbon dioxide emissions by 2050. This commitment puts commercial aviation in line with the Paris Agreement goal of keeping global average temperature rise well below 2°C (3.6°F). In October 2022, the International Civil Aviation Organization (ICAO), a UN agency composed of aviation representatives from 193 nations, adopted an aspirational goal of net-zero carbon dioxide emissions from international flights by 2050.
IATA says achieving net-zero emissions by 2050 will require removing at least 1.8 gigatons of carbon dioxide from aviation operations in 2050, and removing a cumulative 21.2 gigatons of carbon dioxide from now until mid-century. IATA and A4A maintain that success will depend on collaborative efforts by the entire aviation industry’s value chain, including the airlines, aircraft and engine manufacturers, fuel producers, and aviation navigation service providers, as well as program and policy support by governments.
In 2010, more than a decade before these commitments were made, ICAO called for its member countries to create state action plans describing how they would reduce the impact of their aviation industries on the climate, and requested that countries update these commitments every three years. According to ICAO, 149 countries, accounting for 99% of aviation’s global revenue-ton kilometers, have submitted plans. Building on plans submitted in 2012 and 2015, U.S. Transportation Secretary Pete Buttigieg introduced the United States 2021 Aviation Climate Action Plan at the November 2021 UN climate summit (COP26) in Glasgow, Scotland. The United States formally updated its state action plan with ICAO in February 2022, and released an updated 2024 Aviation Climate Action Plan this December.
In its 2021 aviation plan, the U.S. government stated that its official climate target for commercial aviation is net-zero greenhouse gas emissions by 2050, which entails cutting emissions of nitrous oxide and methane in addition to carbon dioxide. The goal includes emissions from domestic flights (operated entirely within the United States and its territories by U.S. and foreign operators), international flights by U.S. airlines between two ICAO member states, and emissions from airport operations.
The United States and the global air transport industry plan to reduce aviation’s climate impact by employing four primary strategies. The first is making fuel efficiency improvements through advances in aircraft technology, mainly in engine and airframe design. The second strategy is reducing the amount of fuel burned by making air traffic control, airport, and inflight operations more efficient. Third, the industry is ramping up its use of sustainable aviation fuels (SAF) produced with significantly lower life-cycle carbon emissions than conventional fossil-derived jet fuel. To address emissions that cannot be avoided, the fourth strategy is carbon offsetting, where airlines invest in out-of-sector carbon reduction measures to compensate for residual emissions.
ICAO data from 135 action plans indicate countries will employ some or all four primary strategies. Credit: ICAO
The 2024 U.S. Aviation Climate Action Plan adds electrification and hydrogen fuel as potential strategies for smaller aircraft in short-haul operations in the decades ahead. However, the Plan describes technology barriers that will preclude the use of these propulsion sources for medium- to long-haul flights which are responsible for most of commercial aviation’s emissions. Fuel cell efficiencies must increase for broader electrification, and the large volume requirements of hydrogen will require improvements in storage technology.
The 2021 U.S. Aviation Climate Action Plan identifies the strategy for reaching net-zero aviation emissions as requiring a “whole-of-government approach.” This graphic illustrates the enormous challenge in getting to net-zero emissions, and the strategies needed to meet that challenge.
Analysis of Future U.S. Domestic and International Aviation CO2 Emissions
United States 2024 Aviation Climate Action Plan
The graph projects U.S. commercial aviation will produce just under 500 million tons of CO2 by 2050 with the air traffic growth projected by mid-century, assuming current aircraft technology for the fleet and no other abatement strategies are employed. As airlines acquire new aircraft to replace less efficient older models, the abatement target decreases to just above 350 million tons. New technology incorporated in the fleet between 2035 and 2050 reduces the target by an additional 50 million tons. Operational efficiencies such as improved air traffic management and airport operations could contribute roughly 10 million tons of CO2 emission reductions, and the largest share of emissions mitigation would be from the use of SAF, which would abate between 150 to 300 million tons of CO2. Currently, SAF is blended with conventional fossil jet fuel up to a maximum of 50 percent SAF. The graph depicts abating the remaining 150 million tons of carbon by using 100% SAF for all domestic flights, including those of foreign carriers, as well as international flights by U.S. carriers.
To learn more about specific U.S. programs being developed to reach these goals, read the next article in the series on U.S. government and industry programs designed to reduce aviation’s greenhouse gas emissions.
Author: Jeff Overton
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