A brewing 'Super El Niño' is poised to unleash heat waves, floods and drought worldwide — but what if we could simply switch it off?
That provocative question is at the heart of a new study published Wednesday in Science Advances, which used powerful climate models to test whether artificial marine cloud brightening over the equatorial Pacific could neutralize the influential weather phenomenon.
The research, led by Dr. Jessica Wan of the University of Chicago, was inspired by a 'natural experiment': the 2019-2020 'Black Summer' bushfires in Australia, whose smoke particles inadvertently brightened clouds, bouncing more sunlight back to space and contributing to a multi-year La Niña.
The team simulated what would happen if ships equipped with sea-salt-spraying nozzles brightened clouds over a vast rectangular zone in the eastern tropical Pacific during the 1997-98 and 2015-16 El Niño events. The intervention worked best when started early — in June — and continued through February.
The modeled cloud brightening reversed most temperature and precipitation effects: regions that warmed under El Niño cooled, wet areas dried, and vice versa. "The reason people would ever care about this is not temperature in a box in the Pacific, but how the impacts translate over land," Wan told AFP.
But the catch is substantial. The technology isn't ready — teams worldwide are developing the nozzles, but they can't yet produce enough sea salt spray. Even if perfected, roughly 2,400 ships would be needed for meaningful impact.
Moreover, the models showed unintended consequences, including warming over Europe and Asia. The study did not examine long-term impacts of repeated use. Critics argue geoengineering creates a moral hazard by letting polluters off the hook, but Wan counters: "We're beyond the point where we could just turn off emissions today and be totally fine. We're locked into warming already."
With a 'Super El Niño' potentially forming in 2026, the research arrives at a critical moment in the debate over whether humanity should deliberately engineer the climate.
