Researchers have proposed a controversial geoengineering technique, stratospheric aerosol injection (SAI), as a potential method to mitigate the severity of an anticipated Super El Niño and protect the world's oceans from extreme heatwaves. The method involves injecting sulfur-based particles into the upper atmosphere to reflect solar radiation back into space, thereby cooling the planet.
According to computer simulations, SAI could shield up to 75% of the world's oceans from escalating heatwaves, which are a key factor fueling the current extreme El Niño cycle. This approach aims to prevent the buildup of hot water in the Equatorial Pacific, a condition that drives El Niño events. Scientists warn that the current El Niño could be the worst in recorded history.
In a "business as usual" scenario, marine heatwaves are projected to intensify and lengthen across 97% of the world's oceans. However, simulations indicate that if SAI is used to cap global warming at 1.5°C (2.7°F) above pre-industrial levels, about a quarter of the ocean would be protected. A more aggressive scenario, limiting warming to 1°C (1.8°F), could see heatwaves become less intense in 76% of the ocean and shorter in 80% of locations. The study highlighted that regions like the tropical Atlantic, Indian Ocean, Arctic Ocean, and South Atlantic Ocean would benefit the most.
However, the benefits are not uniformly distributed. Even with aggressive geoengineering, areas such as the North Atlantic, Tropical Pacific, and parts of the Southern Ocean would still experience worsening heatwaves if global emissions are not reduced. Lead author Dr. Lala Kounta of Michigan State University noted that the "geography of protection is deeply unequal."
El Niño is part of a natural climate cycle known as the El Niño–Southern Oscillation (ENSO), which typically shifts between warm (El Niño) and cool (La Niña) phases every two to seven years. During El Niño, warm waters in the Pacific spread, raising global average surface temperatures. While the cycle is natural, scientists have noted that a massive ocean heatwave in the Pacific, spanning 9,000 miles and forming since late 2025, is contributing to the unusual intensity of the current event. Another marine heatwave extends from Papua New Guinea to the Californian coast, with temperatures up to 3°C (5.4°F) above average.
Despite the potential benefits of SAI, researchers emphasize that it is not a replacement for reducing greenhouse gas emissions. Professor Phoebe Zarnetske of Michigan State University stated, "It's not a substitute for reducing emissions; reducing emissions is still the priority and is the most effective action to mitigate climate change." Previous studies have raised concerns about the potential unintended consequences of solar geoengineering, including disruptions to global weather patterns, tropical monsoon systems, sea levels, and atmospheric circulation.
The World Meteorological Organization (WMO) anticipates above-normal temperatures across nearly all parts of the globe due to the impending El Niño, with particularly strong warming expected in southern and western North America, Central America, the Caribbean, Europe, North Africa, much of Asia, Northern South America, and Southern Africa. Warmer conditions are also forecast for Australia's coasts and tropical regions, including Equatorial Africa and parts of Southeast Asia.
While the proposed geoengineering method offers a potential tool to combat the immediate effects of marine heatwaves and extreme El Niño events, the consensus among researchers remains that substantial reductions in global emissions are the most critical and effective long-term strategy for mitigating climate change.