Flight altitude determines climate impact of hypersonic aircraft

Description

Researchers at the German Aerospace Centre DLR, TU Delft and the Université Paris-Saclay have found that the climate impact of hypersonic aircraft flying on liquid hydrogen at 25 and 35 km altitude is at least 10 to 20 times worse than that of a regular subsonic aircraft at around 10 km altitude serving the same routes and number of passengers. This is due to the accumulation of water vapour in the stratosphere. Water vapour is an important non-CO₂ greenhouse gas that is emitted when liquid hydrogen is burned in a combustion engine. The research shows that the higher in the atmosphere you fly on liquid hydrogen, the greater the climate effect of the water vapour is. Their research paper in the journal Atmospheric Chemistry and Physics was selected as a highlight by the journal. It’s available open access.