Aircraft produce the same types of emissions as cars and trucks. In particular, aircraft jet engines produce carbon dioxide (CO2), water vapor (H2O), nitrogen oxides (NOx), carbon monoxide (CO), oxides of sulfur (SOx), unburned or partially combusted hydrocarbons (also known as volatile organic compounds, or VOCs), particulates, and other trace compounds. Aircraft engine emissions are roughly composed of about 70% CO2, a little less than 30% H2O, and less than 1% each of NOx, CO, SOx, VOC, particulates, and other trace components.
As with surface vehicles, aircraft produce carbon dioxide through combustion of petroleum-based fuel. Aircraft can have complex effects on climate through contrail formation and by emitting water vapor into the dry stratosphere. Aviation accounts for about 10% of greenhouse gas emissions from transportation in the U.S., or about 2.7%of total national greenhouse gas emissions. After plummeting during the pandemic, emissions from aviation rose in 2023 to over 90% of their pre-pandemic level.
GOALS
In 2022, the International Civil Aviation Organization, a UN agency made up of 193 countries, adopted a long-term aspirational goal of net zero carbon emissions from international aviation by 2050.
PROGRESS
Change is coming as the industry works to come to terms with climate change, but, by all measures, it will be slow. A wide range of technologies and innovations are being designed in a bid to tackle aviation’s environmental footprint.
- Blimps! Emitting 90% less carbon dioxide than a standard airplane, blimps are also coming. Bill McKibben found the best description of what they might feel like, in a new world of aviation, in Kim Stanley Robinson’s brilliant sci-fi novel, The Ministry for the Future. "In the novel", he writes "that takeoff felt strange, lofting up over the bay, bouncing a little on the wind, not like a jet, not like a helicopter. Strange but interesting. Dynamic lift; the electric motors, on sidecars up the sides of the bag, could get them to about two hundred kilometers an hour over the land, depending on the winds.”
- The U.S. Air Force's Agility Prime program is working with private industry to explore building innovative aircraft, such as “flying taxis,” also being developed by United Airlines.
- NASA is researching ideas that could lead to the development of electric propulsion-powered aircraft, which would be quieter, more efficient and environmentally friendly than today's commuter aircraft.
- Sustainable aviation fuels (SAFs) currently account for less than 0.1% of all aviation fuels consumed, while all planned SAF projects will meet 2-4% of jet fuel demand by 2030.
- Fuel cell-powered and battery electric test flights are taking place. In 2023, ZeroAvia flew a 19-seat aircraft with a hydrogen-electric engine and Universal Hydrogen flew a 40-seat aircraft with a fuel cell engine. Battery electric aircrafts produce no direct emissions, but are currently limited to small aircrafts and short ranges. In 2023, a 4-tonne civil electric aircraft was tested successfully.
- Airbus and Ariane Group are building the first liquid hydrogen refueling facility at an airport in Toulouse, France.
Increasing 
