The true impact of flights could be far greater than we thought because, mathematically speaking, two-thirds of the total impact on climate change is made up of emissions other than CO₂.

Apart from this greenhouse gas, aircraft engines also release other combustion products when burning fuel, such as nitrogen oxides and sulphur dioxide, as well as particulate matter like soot. All of these contribute to the so-called non-CO₂ climate impact.

At high altitudes, these emissions can affect the physical and chemical properties of the atmosphere, leading to an increase in the amount of greenhouse gases and the formation of condensation trails. As a result, the "net" impact on the climate is greater than the impact of CO₂.

A European Commission report, which used the latest available scientific data, was published in 2020 and found that the non-CO₂ impact of aviation is twice as large as the direct impact of CO₂.
https://www.euronews.com/green/2022/05/04/co2-emissions-just-the-tip-of-the-iceberg-for-the-climate-cost-of-air-travel
Photo by Christophe Ena/File used