What share of global CO₂ emissions come from aviation?
Flying, despite constituting just 2.5% of global carbon emissions, remains one of the most carbon-intensive activities. This seemingly paradoxical statistic is due to the fact that only about 10% of the world's population flies regularly. However, as incomes rise globally, more people are expected to fly, driving up demand and emissions.
Over the past decades, aviation emissions have soared due to increased demand and only modest improvements in efficiency. From 1990 to 2019, while aviation became over twice as energy-efficient per passenger-kilometer, global demand quadrupled. This efficiency gain has somewhat offset emissions growth, but overall CO2 emissions from aviation doubled during this period, reaching around 1 billion tonnes annually by 2019.
Despite improvements in technology and efficiency, the carbon intensity of aviation fuel has remained unchanged. This means that although flying has become more efficient in terms of energy use per kilometer, the carbon emissions per passenger-kilometer have still decreased significantly—from 357 grams of CO2 in 1990 to 157 grams in 2019.
Aviation's contribution to global warming goes beyond CO2 emissions. The sector also emits other gases and pollutants, which collectively contribute to a warming effect stronger than what CO2 alone would suggest. Aviation's overall impact on global warming, including these factors, amounts to around 4% of the total effect observed since pre-industrial times.
Looking ahead, aviation's share of global emissions is likely to increase as other sectors decarbonize more rapidly. The industry faces challenges in transitioning to low-carbon alternatives such as electrification, biofuels, or hydrogen due to technological and infrastructural barriers. Without significant progress in these areas, aviation will continue to constitute a growing share of global emissions in the future.