Brightening clouds by spraying sea salt particles into the atmosphere could lessen the climate impacts of a super El Niño, a new study suggests.
The research published in Science Advances on July 8, 2026, demonstrated the possibility that targeted marine cloud brightening (MCB) could modify El Niño on a seasonal timescale and reduce some of its associated remote climate effects.
In the study, researchers led by Jessica S Wan from the Scripps Institution of Oceanography investigated whether a proposal called MCB could mitigate the extreme weather that El Niño brings.
MCB is the idea that the Earth can be cooled by adding tiny particles into the lower atmosphere over the ocean. When these tiny particles, for example sea salt, interact with clouds, they form lots of little cloud droplets that make the cloud tops more effective at bouncing sunlight back to space and cooling the ocean underneath.
The local cooling changes global dynamics in winds, waves and precipitation in other regions of the world outside of the region where marine cloud brightening is being implemented, which makes it potentially a very powerful tool to damp El Niño, which has global effects. Combined with current El Niño forecasting capabilities, the researchers modeled the efficacy of implementing seasonal marine cloud brightening to weaken a forecasted super El Niño.
An attempted real-world field test could lead to disastrous unintended consequences but the “Black Summer” bushfires that scorched Australia in 2019 and 2020 served as a natural experiment. Researchers demonstrated that the “natural” cloud brightening and ensuing La Niña-like response can be reproduced by simulating MCB in the southeast Pacific.
The scientists then explored how MCB modifies the 1997-1998 and 2015-2016 El Niño events. MCB initiated during the El Niño growth phase disrupts the Bjerknes feedbacks (positive feedback between tropical Pacific surface wind and ocean temperature) that normally amplify El Niño conditions, but those effects weaken after MCB is terminated.
“As long-term anthropogenic warming and short-term natural variability often compound to produce extreme weather events, our findings suggest that it may be worth considering interventions which target natural variability, rather than the forced response to greenhouse gases,” said researchers in the study. “Such an approach could result in similar physical risk reduction with shorter duration interventions that carry less socio-technical risk than a sustained deployment.”
The study cautioned that weakening El Niño could result in unintended consequences including an earlier La Niña following the targeted El Niño, although early and short interventions may counter these effects. The results support the consideration of climate variability and teleconnections as targets in solar geo-engineering research.
“We find MCB is effective at reducing the warming and wetting impacts of El Niño when implemented early in the event,” said Jessica Wan.
The researchers said they are not aware of any proposals to test this on the El Niño brewing now, but as research progresses, actual geoengineering schemes could be considered by government-level decision makers in the future.
The authors say the analysis could not have been possible without a 2023 study led by John Fasullo, National Center for Atmospheric Research and also one of the co-authors of the study. Fasullo’s team charted the effects of the bushfire smoke that mixed with clouds over the southeastern Pacific Ocean.