As rocket launches surge to record levels, scientists are sounding the alarm over an old environmental concern, ozone damage. A new study led by Laura Revell at the University of Canterbury suggests that unchecked growth in launch activity could delay the ozone layer’s recovery by years or even decades.
The ozone layer shields Earth from harmful ultraviolet radiation. Decades ago, it faced widespread damage from chlorofluorocarbons (CFCs), triggering a global ban under the 1989 Montreal Protocol. Since then, levels have slowly rebounded. But researchers now believe rocket exhaust and re-entry debris could be slowing that progress, just as launch rates skyrocket.
Launch Growth and Lingering Emissions
Back in 2019, the world saw fewer than 100 orbital launches. In 2024, that figure hit 258. By 2030, projections suggest more than 2,000 launches per year if current growth continues, driven largely by the satellite constellation boom.
A significant issue, on top of the sheer scale of the launches, is the altitude. Rockets and re-entering debris release emissions into the middle and upper atmosphere, where pollutants like soot and chlorine gas stick around much longer than they would at ground level. These compounds disrupt ozone chemistry, either by directly breaking down ozone molecules or by accelerating other harmful reactions.
The modelling work, built using systems from ETH Zurich and the PMOD/WRC in Davos, projects a 0.3% global drop in average ozone by the end of the decade. That figure climbs to a 4% seasonal drop over Antarctica, a region already dealing with an annual ozone hole that hasn’t closed. These effects might seem minor, but there is a bigger picture. The global ozone layer is still about 2% below where it was before industrial damage began. Recovery is slow. Without new interference, it’s not expected to return to pre-1980 levels until around 2066. Any new pressure could push that date further back.
Fuel Types and Re-Entry Risks
Solid-fuel rockets are the biggest concern, thanks to their chlorine emissions. Liquid-fuel rockets, especially those using cryogenic oxygen and hydrogen, have far less impact, but only make up a small slice of global launch activity. More than 90% of today’s rockets still use fuels that either emit soot or chlorine or both. On top of this, most models don’t yet factor in emissions from re-entering satellites. As more spacecraft complete their orbits and fall back into the atmosphere, they burn up, releasing heat-driven pollutants like nitrogen oxides and metal particles. These are believed to further damage ozone, though the mechanisms are still being studied.
Scientists behind the study argue that this risk can be managed, but not ignored. Cleaner propulsion, better monitoring, and regulatory oversight could prevent long-term harm. They point to the Montreal Protocol as proof that global coordination can fix large-scale environmental problems. But as the pace of launches accelerates, any delay in action only raises the odds that the ozone layer’s recovery will stall, again.
