The French Academy of Sciences has released a report recommending a global prohibition on any public or private initiative aiming to modify solar radiation to artificially cool the planet. The document warns that the use of stratospheric aerosols to reflect part of the sun’s rays could trigger “uncontrollable climate chaos”, with potentially disastrous consequences for ecosystems and human activities.
A high-risk technology with global impact
Among the geoengineering techniques considered, the injection of reflective aerosols—such as sulphur particles into the stratosphere—is gaining attention for its ease of deployment. This method imitates the cooling effect of a volcanic eruption by temporarily lowering average global temperatures. However, the French Academy of Sciences highlights that an abrupt halt to such a process could cause a rapid warming event, referred to as a “termination shock”, leading to sudden and uneven climate disruptions across regions.
Risks associated with this method include poorly understood effects on human health, precipitation patterns, the ozone layer and agricultural productivity. The possibility of a sudden interruption could destabilise critical infrastructure and result in significant economic losses, particularly in countries most vulnerable to climate fluctuations.
Major economic implications
The report also emphasises the economic uncertainties of this approach. Sudden and unpredictable climate instability could impact commodity markets, complicate industrial planning, and increase adaptation costs for both governments and businesses. “The potential benefits would not outweigh the likely negative consequences,” the Academy warns, calling for a worldwide ban on this approach.
According to experts, focusing on such solutions could divert funding and delay necessary investment in emissions reduction technologies. “This approach may amount to a mirage,” said climatologist Valérie Masson-Delmotte during a scientific seminar.
Targeted research oversight
Despite these warnings, the Academy does not completely rule out some forms of geoengineering. The report recommends continuing research into negative emissions methods, such as carbon dioxide (CO2) storage in soils, living biomass or via the oceans. It also calls for the development of direct air capture technologies for atmospheric CO2.
Academician Laurent Bopp, co-author of the report, stated that CO2 removal will be unavoidable to achieve carbon neutrality, as foreseen in most pathways aligned with the Paris Agreement. The stated goal is to separate viable technological options from those to be permanently ruled out.
“There are still major knowledge gaps and we need to push forward with research,” concluded oceanographer Jean-Pierre Gattuso, highlighting the importance of rigorous scientific oversight to avoid technological missteps and unforeseen economic effects.
