PACIFIC OCEAN — Researchers published findings on July 8, 2026, in Science Advances, indicating that marine cloud brightening over the Pacific Ocean may reduce the intensity of El Niño events. This conclusion is based on computer simulations and an analysis of atmospheric effects from historical wildfires.

Marine cloud brightening involves injecting aerosols, such as sea salts, into the atmosphere to make ocean clouds brighter. These brightened clouds reflect more solar radiation into space, which contributes to cooling the planet. Computer simulations indicate that enhancing cloud brightness in the Pacific could initiate atmospheric changes that lessen the strength of an El Niño event.

The research team, which included climate scientist Jessica Wan, simulated the effects of marine cloud brightening on the 1997–1998 and 2015–2016 El Niño events. Wan conducted research on wildfire impacts while at the Scripps Institution of Oceanography. The simulations targeted areas in the southeastern Pacific Ocean where fire particles were most concentrated. The team simulated an aerosol injection concentration of approximately 500 particles per cubic centimeter. All simulated aerosol injections resulted in weaker El Niño events when compared to the actual historical occurrences. The simulations also varied the timing of aerosol injections, testing scenarios at the beginning of an El Niño, near its peak, and with different durations. Wan stated, "We wanted to try to go full hammer to see what happens."

For the 2015–2016 El Niño simulation, injecting particles from June through the following February created the strongest cooling effect. Conversely, starting aerosol injections in December for the 2015–2016 simulation resulted in the least amount of cooling. The 2019–2020 Australian wildfires released particles into the atmosphere that subsequently moved over the southeastern subtropical Pacific Ocean. These particles brightened clouds over that region and contributed to triggering a multiyear La Niña event.

Daniele Visioni, a climate scientist at Cornell University who was not involved in the study, said, "Using MCB to directly target large El Niños is really interesting and very new." Visioni added, "And the fact that it looks like this could work is a really good indication that it is something worth thinking about." Earth entered its most recent El Niño phase in June 2026, and computer simulations of current Pacific conditions suggest the potential for a super El Niño.

James Haywood, a climate scientist at the University of Exeter in England, was not involved in the new study. Haywood noted, "There are many, many unanswered questions and uncertainties as to the viability of MCB." Previous research by Haywood and his colleagues found that cooling the eastern Pacific through marine cloud brightening might lead to a mega La Niña. Wan commented, "But the impacts of both El Niño and La Niña are heterogeneous around the planet, and not everyone suffers or benefits from either."