REVEAL-NOx: reducing the uncertainty in the climate impacts of aviation nitrogen oxide emissions

Even the burning of sustainable aviation fuels produces nitrogen oxides (NOx) from the heating of air in jet engines, placing these pollutants as somewhat inescapable products of the aviation industry. The NOx produced have large but complex short-term warming effects as they generate tropospheric ozone, a strong greenhouse gas. Yet in the longer term, they reduce the concentration of ozone, giving a moderate cooling effect. Despite the knowledge of variable climatic impacts, the relative importance of the warming and cooling effects remain poorly understood.

In response to this knowledge gap, this project aims to better constrain these warming and cooling effects using an ensemble of climate models, validated against experimental measurements including from the (now retired) UK FAAM plane. This will better inform future efforts to reduce the climate impact of aviation, as NOx-caused warming is affected by flight routing as well as fuel choice and engine technology.