Scientists are exploring the radical concept of stratospheric aerosol injection, a form of solar geoengineering, as a potential measure to mitigate the severity of an approaching "Super El Niño." This approach involves releasing tiny sulfur-based particles into the upper atmosphere to reflect solar energy back into space, thereby cooling the planet and shielding oceans from extreme heatwaves.
Researchers have simulated scenarios showing that such an intervention could significantly reduce the intensity and duration of marine heatwaves. According to computer models, capping global warming at 1.5°C (2.7°F) above pre-industrial levels could shield about a quarter of the world's oceans from worsening heatwaves. A more aggressive scenario, limiting warming to 1°C (1.8°F), could protect up to 76% of the ocean from hotter heatwaves and 80% from longer ones. Regions like the tropical Atlantic, Indian Ocean, Arctic Ocean, and South Atlantic Ocean showed the most benefit in these simulations.
However, the effectiveness of this geoengineering method is geographically uneven. Even with aggressive implementation, areas such as the North Atlantic, tropical Pacific, and parts of the Southern Ocean would still experience intensifying heatwaves if emissions are not reduced. "The geography of protection is deeply unequal," noted lead author Dr. Lala Kounta of Michigan State University.
The impending El Niño event is predicted to be one of the most severe on record, potentially fueled by a massive ocean heatwave in the Pacific that has been developing since late 2025. This heatwave, spanning 9,000 miles, along with another stretching from Papua New Guinea to the Californian coast, is contributing to unusually high sea surface temperatures. Scientists warn that the warming in the North Pacific could reduce winds, impacting the equator and potentially initiating conditions necessary for El Niño. The 2026 El Niño could, in turn, amplify existing North Pacific marine heatwaves, leading to significant consequences.
Despite the potential of solar geoengineering to curb marine heatwaves, the study's authors and other experts emphasize that it is not a substitute for reducing greenhouse gas emissions. "Reducing emissions is still the priority and is the most effective action to mitigate climate change," stated co-author Professor Phoebe Zarnetske of Michigan State University.
Concerns also remain regarding the potential side effects of stratospheric aerosol injection. Previous studies have indicated that the deployment of aerosols could disrupt global weather patterns. For instance, releases in polar regions might interfere with tropical monsoon systems, affecting sea levels. Concentrating releases in equatorial regions could alter atmospheric circulation patterns that transport heat towards the poles. "Change the solar radiation heating at one place, may lead to change of atmospheric pattern in other places," commented Dr. Ying Chen, an expert on cloud brightening at the University of Birmingham, who was not involved in the study.
El Niño is part of the El Niño-Southern Oscillation (ENSO) cycle, a natural phenomenon that shifts between warm (El Niño) and cool (La Niña) phases every two to seven years. During an El Niño phase, warm waters in the Pacific spread, raising global average surface temperatures and causing predictable disruptions in weather patterns worldwide, including increased temperatures in most regions. While the ENSO cycle is natural, scientists suggest that human-induced ocean warming is intensifying the current El Niño event.