Researchers Find Significant Underreporting of 2019 Aviation Emissions
A new study has revealed that flight-related emissions from 2019 were significantly higher than initially reported. Researchers examined data from more than 40 million flights in 2019 and found total global aviation emissions amounted to approximately 911 million metric tons. This figure is much higher than the 604 million metric tons reported to the United Nations for the same year.
The study underscores that while many countries report emissions to the United Nations under the 1992 international treaty, the United Nations Framework Convention on Climate Change (UNFCCC), developing countries (or non-Annex I countries) aren’t required to submit aviation emissions. Although some countries do choose to report emissions, large gaps remain.
To gain a clearer understanding of aviation emissions, a team of scientists used a high-resolution aviation transport emissions assessment model to calculate emissions for 197 countries in 2019. Their findings, published in the journal Environmental Research Letters, indicate that aviation emissions were about 50% higher than the numbers reported to the UN for that year.
The U.S. had the highest aviation-related emissions of any country when considering both international and domestic flights. The model also revealed that China, which did not report its flight emissions to the UN in 2019, was the country with the second-highest emissions.
The model assessed carbon emissions as well as other pollutants, including nitrogen oxides and sulfur oxides, enabling near real-time emissions tracking. This capability is useful for monitoring emissions even in countries not mandated to report them. Aviation currently contributes about 2% of global emissions, and reducing flight-related emissions is essential to meet net-zero emissions goals by 2050. The study indicates that roughly 1% of global emissions tied to aviation are going unreported.
In 2022, 917 million passengers took more than 15 million flights in the United States, averaging over 42,000 flights per day.
The combustion of fossil fuels for global air travel and airport operations is a significant source of carbon emissions contributing to climate change. In 2022, global aviation produced over 780 million metric tons of CO2, accounting for about 2% of that year's global energy-related CO2 emissions. Aviation emissions have steadily risen over the years, quadrupling between 1966 and 2018.
Air travel contributes to the accumulation of heat-trapping emissions, which in turn creates new and growing challenges for the industry. Weather is already responsible for over 75% of air traffic delays in the U.S. As climate change exacerbates coastal flooding and extreme weather events, there could be an increase in weather-related delays that ground flights. Additionally, a warmer atmosphere may lead to more frequent instances of in-flight turbulence.
