El Niño has returned with unusual strength, prompting researchers to explore solar geoengineering like cloud whitening to weaken its impact on global weather patterns.
El Niño returns with unusual strength
El Niño has returned this year with a strength that concerns climatologists. Researchers are exploring ways to potentially curb its power through experimental methods such as cloud whitening, which could reflect part of the sun's radiation back into space. Study proposes solar geoengineering
A study by climatologist Jessica Wan and her colleagues from the Scripps Oceanography Institute, published in 2026 in Science Advances, suggests that a form of solar geoengineering could weaken an ongoing El Niño. These episodes of warming in the Pacific disrupt global weather patterns, but until now, no method existed to mitigate their intensity. El Niño's mechanism and effects
El Niño occurs when trade winds weaken, allowing warm waters to shift eastward across the equatorial Pacific. This shift can cause disruptions in rainfall patterns worldwide, leading to droughts, floods, heatwaves, and agricultural losses. In 2026, the phenomenon has resumed with unusual strength, with some models suggesting the possibility of a "super El Niño." Inspiration from past events
The idea of acting on El Niño emerged from an unexpected event during the Australian mega-fires of 2019 and 2020. The smoke from these fires altered clouds over the southern Pacific, contributing to a prolonged La Niña phase and demonstrating that atmospheric disturbances can influence the state of the Pacific. Cloud whitening method tested
The study modeled a solar geoengineering approach by targeting a specific region in the eastern subtropical Pacific, simulating the injection of about 500 particles per cubic centimeter above low clouds. Marine salt aerosols used in this method whiten clouds, reflecting more solar radiation and cooling the ocean surface. The researchers tested this approach on two major El Niño events: 1997-1998 and 2015-2016. Timing of the intervention matters
In each case, the simulated El Niño was weaker than the actual event. The timing of the intervention was crucial, with the most significant cooling effect observed when the injection began in June and continued until the following February. Starting in December, when the mechanism was already in motion, had a much smaller effect. In April 2016, the simulated ocean temperature dropped significantly below the actual observed temperature. Challenges remain for deployment
However, nothing of this is close to being deployed against the current El Niño. The simulations do not address technical obstacles or the central political question of whether to accept potential secondary effects on the climate. Cooling the eastern Pacific could cause the system to swing too far, potentially triggering a La Niña of unprecedented magnitude, according to studies using the UKESM1 British climate model. Regional impacts and future steps
El Niño and La Niña do not affect all regions equally. An intervention that could benefit certain countries might worsen conditions elsewhere. For now, this approach remains confined to numerical simulations. Finer models will still need to specify the dosage and schedule before considering any marine experiments.
