As the globe struggles to transition away from fossil fuels, the emergence of a new industry — particularly one involving massive clouds erupting from massive motors — may appear alarming.

Most rockets release more carbon dioxide, which contributes to global warming, than many airlines. One orbital launch of SpaceX's upcoming fully reusable Starship will emit as much carbon dioxide as flying a plane continuously for about three years, and experiencing a few minutes of weightlessness on Virgin Galactic's spaceplane will rack up a carbon footprint comparable to flying business class across the Atlantic.

However, commercial aviation flights outnumber space launches by a factor of 39 million to 114 in 2018, far too many for the space sector to catch up in even the most optimistic circumstances. Rockets today burn just 0.1 percent of the fuel that planes do, resulting in carbon emissions that are a rounding error in comparison.

Rockets launch into the stratosphere, which is home to the protective ozone layer that blocks harmful UV light, therefore space launches are also a source of concern.

Alumina particles and chlorine gas are emitted by most solid rocket engines, which encourage chemical reactions that break down ozone into molecular oxygen. SpaceX and Blue Origin have switched to liquid fuels, which are less harmful but still produce byproducts like water vapour and nitrogen oxides, which can destroy ozone in the upper atmosphere over time.