A recent scientific study indicates that there may be a potential path to mitigate some of the consequences of future El Niño events and global warming by dimming the sun. El Niño typically develops naturally in the tropical Pacific every few years, triggered by weakened trade winds that shift heat from the ocean toward the coast of South America. This shift often pushes global temperatures above average, leading to droughts in certain regions, intense flooding in others, and an increase in Pacific cyclones. When compounded by the warming caused by burning fossil fuels, a strong El Niño can result in economic losses reaching hundreds of billions of dollars.
Deflecting Solar Energy
The research argues that by deflecting solar energy, it might be possible to cool the ocean and help moderate El Niño events before they intensify, effectively staving off the most severe impacts. Katherine Ricke, a coauthor of the study published in the journal Science Advances and a climate scientist at UC San Diego and the Scripps Institution of Oceanography, describes El Niño as a phenomenon where a disturbance in the tropical Pacific rearranges how the global atmosphere retains energy. She labels it as an ultimate pressure point within the climate system.
Marine Cloud Brightening
Ricke and her colleagues investigated the use of marine cloud brightening (MCB) as a method to dim the sun over the Pacific. The technique involves spraying seawater into marine clouds to enhance their reflectivity. While previous pilot projects and randomized controlled trials have tested the technique, they have remained limited to very small scales.
Insights from Natural Events
To overcome the lack of experimental data on MCB, researchers analyzed the catastrophic 2019-2020 Australian bushfire season, which served as a natural proxy. Over 10,000 bushfires raged across the country, releasing nearly 1 million metric tons of smoke into the atmosphere. This represents one of the largest inputs of smoke into the stratosphere ever observed via satellite technology. Past research indicates that the reflective particles within this smoke helped trigger a rare triple-dip La Niña, which is the direct opposite phase of El Niño.
Modeling the Impacts
This event provided researchers the opportunity to address whether regional interventions could relieve the pressure that events like El Niño exert on the global climate system. The team developed a model based on the MCB effects observed during the Australian fires and tested it against two historical El Niño events. The modeling demonstrated that reducing the amount of sunlight reaching the Pacific surface would have significantly lowered the magnitude of those El Niño events and curtailed their global impacts.
Geopolitical and Scientific Challenges
Geoengineering has traditionally been viewed as a global strategy to cool the planet and counter fossil fuel consumption, albeit a highly controversial one. However, some researchers now argue that such techniques could be better utilized to target regional climate issues like El Niño. Andrew Dessler, a professor of atmospheric science at Texas A&M University, acknowledges that the thesis presented in the study is reasonable. However, he warns that implementation would likely be a political nightmare, potentially resulting in conflict or war if unintended consequences arise.
Ricke agrees that there are numerous factors to be resolved through further modeling before any real-world application is considered. She emphasizes that the primary reason for conducting research into solar geoengineering is the possibility that humanity may eventually find itself in a position where such measures are necessary, especially if efforts to curb fossil fuel pollution fail.
