Scientists are investigating a geoengineering technique known as marine cloud brightening, which could potentially counteract the severe weather events associated with the current Super El Niño. The method involves injecting small particles, such as salt, into the atmosphere to make clouds over the equatorial Pacific more reflective, thereby reducing the amount of heat reaching the lower atmosphere. According to a study published in Science Advances, this could be potent enough to shift a heat-generating El Niño year into a cooling La Niña phase.
Researchers suggest that deploying this technique in the Pacific Ocean before a Super El Niño could enhance the cooling and drying effects typically associated with La Niña by over 40 percent. Dr. Katharine Rick, a climate scientist at the University of California San Diego and co-author of the study, stated that while much more research is needed, the possibility of using this method in conjunction with other risk reduction tools to mitigate El Niños warrants consideration.
While the scientific consensus remains that reducing greenhouse gas emissions is the primary strategy for combating climate change, the intensifying climate crisis is prompting a re-examination of geoengineering approaches. Marine cloud brightening aims to create a localized cooling effect by making clouds act like a natural sunscreen, potentially leading to significant weather changes beyond the direct area of intervention.
The researchers acknowledge the uncertainties surrounding marine cloud brightening and consider a real-world test too risky at present. However, they drew inspiration from the 2019-2020 Australian bushfires, whose massive smoke plumes created an effect similar to geoengineered aerosols. Previous research indicated that these smoke-brightened clouds contributed to cooling, La Niña-like weather patterns in the southeastern Pacific Ocean.
Building on this, the scientists modeled the potential impact of artificial cloud brightening applied before major El Niño events in 2015 and 1997. Their simulations indicated that such an intervention could dampen El Niño's effects, with earlier deployment yielding a stronger outcome. The study's lead author, Dr. Jessica Wan from the University of Chicago, noted that a key advantage of targeting natural variability like El Niño, rather than long-term climate trends, is that the intervention would not need to be continuous indefinitely, addressing a significant societal concern about geoengineering.
El Niño and La Niña are alternating phases of the El Niño-Southern Oscillation (ENSO), a climate pattern in the tropical Pacific. El Niño is characterized by warmer ocean surface temperatures, leading to reduced rainfall in some regions and increased rainfall in others, along with weakened easterly winds. La Niña brings cooler ocean surface temperatures, often resulting in increased rainfall over Indonesia and stronger easterly winds.
The researchers are not aware of any plans to test this method on the current Super El Niño, but they suggest it could be an option for governments to consider in the future. The potential deployment of geoengineering on a global scale remains highly controversial due to unknown long-term consequences, with some studies suggesting that certain techniques could exacerbate climate change impacts. However, the authors argue that the severe economic and societal damage projected from a Super El Niño might justify a more controlled application of marine cloud brightening to mitigate its worst effects without permanently altering the climate.