The satellite industry's rapid growth is sparking concerns about an unintended environmental experiment. As companies like SpaceX plan to launch millions of satellites, scientists warn of potential climate impacts. The issue lies in the release of black carbon, or soot, from rocket launches, which can have a cooling effect on the atmosphere, similar to geoengineering solutions like stratospheric aerosol injection. However, this cooling effect is minimal compared to global temperature rise driven by greenhouse gas pollution.
A recent study by Eloise Marais and her team at University College London projects that by 2029, megaconstellations will contribute nearly half of the climate impact from space sector pollution, with black carbon from rocket launches being a major contributor. This rapid growth in satellite deployment is a significant driver of the commercial launch boom, with revenue from commercial satellites accounting for 71% of the world's space business in 2025. The study's findings highlight the need for better assessment of the industry's environmental impact and the potential risks associated with unregulated growth.
The researchers found that black carbon from kerosene-fueled rocket launches has a much longer atmospheric lifetime than soot from ground-based sources, leading to a 500 times greater cooling effect. However, this is still a small fraction of the global temperature rise caused by greenhouse gas pollution. The study also investigated the potential depletion of the ozone layer by megaconstellation pollution, but found that the impact is small due to the lack of strong ozone-depleting chlorine compounds in most rockets. Nevertheless, the potential for future changes in rocket propellant usage could lead to more significant ozone layer depletion.
Marais emphasizes the importance of regulation and observation to prevent harm to the environment. Her team is developing an online tracker for launch and re-entry emissions and designing techniques to observe rocket launch pollution using satellite instruments that observe land rather than the air. The goal is to provide policymakers with the necessary information to design regulations that prevent environmental damage, ensuring a sustainable future for generations to come.
