Cutting off solar geoengineering abruptly could trigger a “termination shock” of rapidly rebounding temperatures, making climate damage even more severe than if humanity continues with unabated global warming. This counterintuitive finding underscores the growing risks of relying on geoengineering as a quick fix for the climate crisis.
The Rising Interest in Solar Geoengineering
As greenhouse gas emissions climb, the idea of temporarily cooling the planet via solar radiation modification (SRM) is gaining traction. One proposed method involves injecting aerosols into the stratosphere to block sunlight – a tactic that could mask warming for decades. However, this approach is not a one-time solution. It would require continuous operation for centuries. If halted prematurely, the masked warming would rebound at an accelerated rate, leaving ecosystems and societies with little time to adapt.
The Economic Calculus of Climate Risk
Researchers at the National Autonomous University of Mexico modeled the economic consequences of climate inaction versus SRM. Their analysis suggests that unchecked emissions could lead to a median 4.5°C warming by 2100, causing damages of roughly $868 billion. A well-managed stratospheric aerosol injection program could theoretically halve these losses by keeping warming closer to 2.8°C. But… if that program were suddenly terminated in 2030, temperatures rebounding by just 0.6°C over eight years could push damages above $1 trillion. The key takeaway: a sudden stop would be worse than doing nothing at all.
The Governance Paradox
The viability of SRM hinges on extremely low failure rates. To avoid termination shock, aerosol injection would need to continue with an annual interruption probability of just a few tenths of a percent. Or, if termination were unavoidable, it would require a phased withdrawal over 15+ years. The problem is that maintaining such stability requires unprecedented international cooperation – cooperation that is actively being undermined by major players like the U.S. The paradox is that if global emissions were under control, the need for SRM would diminish.
Private Sector Involvement and Future Trends
Despite the risks, private companies are already experimenting with SRM. Start-ups like Make Sunsets have released sulphur dioxide into the stratosphere, while Stardust has lobbied governments for funding. A recent survey suggests that two-thirds of scientists expect large-scale SRM deployment this century. Successfully cooling Earth by 1°C would require a sustained, coordinated effort involving at least 100 aircraft dispersing millions of tonnes of aerosols annually.
Ultimately, the study suggests that research into solar geoengineering isn’t necessarily a slippery slope to deployment, but it does highlight the extreme governance challenges involved. The need for near-perfect reliability underscores the fact that the most effective solution remains reducing greenhouse gas emissions.
