In a groundbreaking study, an international research team led by Laura Revell from the University of Canterbury has unveiled potential threats to the ozone layer from increasing rocket emissions. Utilizing a chemistry climate model developed at ETH Zurich and the Physical Meteorological Observatory in Davos, the team projected the impact of rocket launches on the ozone layer by 2030. The findings suggest that if rocket launches increase to 2,040 annually by 2030—an eightfold rise from 2024 levels—there could be a nearly 0.3% decline in global average ozone thickness, with seasonal reductions reaching up to 4% over Antarctica.
These projections are particularly concerning given the ongoing recovery of the ozone layer from damage caused by chlorofluorocarbons (CFCs), which were banned under the Montreal Protocol in 1989. Despite this ban, the global ozone layer remains approximately 2% thinner than pre-industrial levels and is not expected to fully recover until around 2066. The study indicates that unregulated rocket emissions could further delay this recovery by years or even decades.
Rocket Propulsion and Ozone Depletion
The study highlights the significant role of rocket fuel in ozone depletion. Gaseous chlorine and soot particles from rocket emissions are the main culprits. Chlorine accelerates the destruction of ozone molecules, while soot particles enhance warming in the middle atmosphere, expediting ozone-depleting reactions. Currently, only cryogenic fuels like liquid oxygen and hydrogen, which are used in about 6% of launches, have a negligible effect on the ozone layer due to their technological complexity.
Uncertain Re-entry Effects
While the study primarily focused on emissions during rocket ascent, it also acknowledged the potential impact of satellite re-entry. As satellites burn up upon re-entering the atmosphere, they release pollutants such as metal particles and nitrogen oxides. These substances can catalyze ozone depletion and contribute to the formation of polar stratospheric clouds, which exacerbate ozone loss. However, these re-entry effects are not yet fully understood or incorporated into atmospheric models, highlighting a critical gap in current research.
“With increasing satellite constellations, re-entry emissions will become more frequent, and the total impact on the ozone layer is likely to be even higher than current estimates,” the study authors noted.
Call for Coordinated Action
The researchers urge for foresight and coordinated action to mitigate the potential threats posed by rocket emissions. They advocate for monitoring rocket emissions, minimizing the use of chlorine and soot-producing fuels, promoting alternative propulsion systems, and implementing necessary regulations. Such efforts will require collaboration between scientists, policymakers, and the space industry.
The Montreal Protocol serves as a successful example of global cooperation in addressing environmental threats. As we enter a new era of space exploration, similar international coordination will be essential to protect the ozone layer, one of Earth’s most vital natural shields.
This article was co-authored by Sandro Vattioni and Timofei Sukhodolov from the Physical Meteorological Observatory Davos.
