This year’s El Niño will soon become one of the strongest on record and will cause chaos around the world.
A novel study suggests there could be a way to mitigate some of the effects of future El Niño and global warming: dimming the sun.
El Niño develops naturally in the tropical Pacific every few years, caused by weakening trade winds that push heat out of the ocean toward the coast of South America. This increases the risk towards higher than average global temperatures, as well as droughts in some regions, intense rain and flooding in others, and more cyclones in the Pacific. A powerful El Niño, superimposed on warming caused by the burning of fossil fuels, could mean hundreds of billions in economic losses.
A novel study shows that deflecting solar energy can nippy the ocean and facilitate mitigate El Niño events before they become too severe, staving off the worst effects.
“El Niño is one of those situations where something happens in the tropical Pacific and then later this year changes the way the entire global atmosphere holds energy,” says Katherine Ricke, co-author of the study published Wednesday in the journal Science Advances and a climate scientist at the University of California, San Diego and Scripps Institution of Oceanography. “This is the highest pressure point in the climate system.”
Ricke and her co-authors looked at using marine cloud brightening (MCB) as a way to dim the sun in the Pacific. This technique involves spraying seawater onto marine clouds to boost the reflectance of the clouds. Although some pilot projects and randomized controlled trials have tested the effectiveness of this technique, these have only been conducted on a very diminutive scale.
MCB is one of several different ones Solar geoengineering methods whose task is to reflect sunlight back into space. Other methods, such as using airplanes to inject aerosols into the stratosphere, can only work globally. However, MCB has the potential to become a regional cooling solution.
To get around the lack of experimentation with MCBs, researchers looked at a recent natural phenomenon that mimicked them: Australia’s disastrous 2019–2020 bushfire season. There have been more than 10,000 bushfires across the country, causing almost 1 million tons of smoke. This represents one of the largest inflows of smoke into the stratosphere that humans have observed using satellite technology.
While the effects of this massive amount of smoke were convoluted, previous research has shown that it helped trigger a infrequent triple wave of La Niña – the opposite phase of El Niño – thanks in part to reflective particles in the smoke.
Ricke says the event allowed her and her co-authors to finally answer a long-held question about whether regional interventions can facilitate alleviate the pressure that events like El Niño put on the global climate system. Scientists created a model based on the MCB effects of the Australian bushfires and compared it to two different historical El Niño events to observe its effects. Modeling showed that reducing the amount of sunlight reaching the surface of the Pacific Ocean would significantly reduce the scale of El Niño events and their global impact.
Geoengineering techniques have traditionally been seen as a way to nippy the entire planet, counterbalancing human utilize of fossil fuels – although this is an extremely controversial method. A novel study shows that some forms of geoengineering could be better used to target regional events such as El Niño. Doing so could potentially prevent – or at least reduce the risk of – the overlapping effects of El Niño on top of human-driven temperature increases.
“The idea of having to keep geoengineering going indefinitely has many people wondering – we all understand that collaboration on such a large scale in the world we live in would be incredibly complex,” says Ricke. “It’s a completely different way of thinking about geoengineering.”