Scientists are exploring whether making clouds reflect more sunlight could help reduce the impact of one of the world’s most disruptive climate patterns.
A new study published in Science Advances suggests that marine cloud brightening, a form of geoengineering, could temporarily weaken extreme El Niño events. The technique involves spraying microscopic sea salt particles into the atmosphere above oceans, increasing cloud reflectivity so that more sunlight is bounced back into space. With less solar energy reaching the ocean surface, temperatures could cool enough to reduce the intensity of El Niño.
The research comes as scientists warn that stronger El Niño events, combined with long-term global warming, are increasing the likelihood of heatwaves, floods, droughts and other extreme weather across many parts of the world.
Using climate simulations, researchers examined how marine cloud brightening might have affected previous El Niño events. Their findings suggest that targeted deployment during particularly severe episodes could reduce some of the associated climate impacts without requiring continuous geoengineering over many years.
The researchers argue that focusing on temporary natural climate fluctuations, rather than attempting to offset long-term global warming indefinitely, may offer a lower-risk approach to testing geoengineering technologies.
Despite these findings, the proposal has generated significant debate within the scientific community.
Critics point out that Earth’s climate system is highly complex, and changes made in one region could have unintended consequences elsewhere. There are also concerns that investment in geoengineering could reduce the focus on cutting greenhouse gas emissions, which remains the primary strategy for addressing climate change.
Questions of governance also remain unresolved. If technologies capable of influencing regional or global weather patterns become viable, countries would need to decide who authorises their use, how risks are assessed and who is accountable for any unintended consequences.
The study does not recommend immediate deployment of marine cloud brightening. Instead, it calls for further research into whether carefully targeted interventions could complement existing climate strategies during periods of extreme natural climate variability.
As climate risks continue to grow, the research highlights how scientific discussions are expanding beyond emissions reduction alone to include new technologies that may help societies manage the impacts of increasingly severe weather events.
