A new study proposes that dimming the sun’s energy reaching the Earth could be a strategy to mitigate the severe weather impacts associated with El Niño events, especially when combined with global warming.
Regional Cooling Approach
El Niño, a naturally occurring phenomenon in the tropical Pacific, happens every few years when trade winds weaken, causing heat to shift toward the coast of South America. This event influences global temperatures, leading to droughts in some areas, heavy rains and floods in others, and an increase in Pacific cyclones. When superimposed on warming caused by fossil fuel emissions, a strong El Niño can result in substantial economic losses.
The research, published in the journal Science Advances, suggests that deflecting solar energy could cool the Pacific Ocean, thereby moderating El Niño events before they intensify and reducing their worst effects. Katherine Ricke, a co-author and climate scientist at UC San Diego and the Scripps Institution of Oceanography, described El Niño as a critical juncture in the climate system that alters how the global atmosphere holds energy.
Marine Cloud Brightening and Bushfire Analogy
The study specifically examined marine cloud brightening (MCB), a solar geoengineering technique that involves spraying seawater into marine clouds to increase their reflectivity. While small-scale trials have explored MCB’s effectiveness, researchers turned to a large-scale natural event to model its potential impact: the catastrophic Australian bushfires of 2019-2020. These fires released nearly 1 million metric tons of smoke into the stratosphere, one of the largest observed inputs of smoke by satellite technology.
Previous research indicates that this smoke contributed to a rare triple-dip La Niña, the opposite phase of El Niño, partly due to the reflective particles it contained. Ricke and her colleagues used this event to investigate whether regional interventions could alleviate the pressure El Niño places on the global climate. They developed a model simulating MCB’s effects based on the bushfires and applied it to two historical El Niño events. The modeling indicated that reducing sunlight reaching the Pacific’s surface could have significantly lessened the magnitude of these El Niño events and their worldwide consequences.
Potential and Caveats
Unlike global solar geoengineering methods, such as stratospheric aerosol injection, MCB offers the potential for regional cooling. While geoengineering is often discussed as a global countermeasure to fossil fuel emissions, this study suggests targeted regional applications could address specific climate phenomena like El Niño, potentially mitigating the compounding effects of natural events and human-induced warming.
However, the concept of geoengineering, even on a regional scale, faces significant challenges. Ricke noted that the idea of sustaining geoengineering indefinitely is complex due to the immense cooperation required. The unpredictability of altering weather patterns and the potential for unintended consequences and political instability have led to skepticism regarding geoengineering proposals.
Andrew Dessler, a professor of atmospheric science at Texas A&M University, called the study’s thesis “quite reasonable” but warned that implementation would be a “political nightmare.” He cautioned that models are imperfect and could lead to unforeseen problems that are worse than the issues they aim to solve. Ricke acknowledged the need for extensive modeling before any real-world application, but emphasized that such research is vital in case it becomes necessary due to a failure to curb fossil fuel pollution.
Helene Elliott is the senior reporter for News Raise. She covers Science news. She also has a keen interest in photojournalism. Helene holds a nomination for the prestigious Red Smith Award. She is married to author Dennis D’Agostino, a former publicist with the New York Mets.
