Scientists call for ‘emergency’ measures to save sea life from El Niño

Prominent scientists have called for “emergency” interventions to protect marine life as the strongest-ever El Niño heats the ocean to unprecedented levels, including removing endangered species from the water and experimenting with geoengineering. “We shouldn’t just cry into our beer about it. We should actually try and do things about it,” says Michael Meredith at the British Antarctic Survey, one of the authors of a journal article that is being sent to officials in the UK, the US and other governments. “Some of them are emergency actions… The more we can do now, the better, and it has to be done quickly.” A record-breaking super El Niño has begun spreading warm water across the Pacific Ocean, raising global temperatures and unleashing extreme weather. Because that burst of heat comes on top of 150 years of global warming, sea surface temperatures could reach 4°C above average in the east-central Pacific, 60 per cent higher than the previous record. Advertisement El Niño has already helped fuel the ocean’s hottest ever month in August. More heat could cause some ocean ecosystems and keystone species, such as coral reefs or Antarctic krill, to collapse. “Things like El Niños… are more likely to push you past those tipping points,” Meredith says. “So once this El Niño passes… the ocean ecosystem… may stay in a new state.” Past super El Niño events have collapsed fisheries such as Peru’s anchovy catch. Governments should limit fishing to give these depleted fish and shellfish populations a better chance to recover, the scientists argue. They could also ban the harvest of predators like the sheephead wrasse, which helps protect California kelp forests from sea urchins. “There are some proven interventions… [that] are relatively low-cost,” says John Bruno at the University of North Carolina at Chapel Hill, another author of the paper. Researchers should stage “rescue missions” to take endangered specimens out of the ocean and house them until temperatures subside, the article adds. During the 2023-2024 El Niño, for instance, scientists moved 25 rare Tasmanian red handfish into tanks, then later returned them to the wild. Others temporarily put corals into aquariums. The scientists also suggest tests of localised geoengineering techniques, such as spraying tiny particles of seawater into low clouds, where moisture condenses onto them. This increases the number of droplets in the clouds, making them more reflective of sunlight and cooling the ocean. Australian scientists have been conducting cloud brightening field trials to shade the Great Barrier Reef, and the UK government has funded this team and others working to develop better spray nozzles. The article also cites artificial upwelling, in which pumps or long pipes would bring cold, nutrient-rich water from the ocean depths to its surface. A study this month that trialled a floating, wave-powered pump in the Gulf of Maine found that artificial upwelling can accelerate kelp growth. Another possible approach is shade structures, such as the ones that conservationists have tried stretching over partially bleached corals in Florida. Scientists could even apply probiotic microbes to corals, says Bruno. This treatment allowed corals to continue photosynthesis during a marine heatwave in the Red Sea while other corals slowed down, a study earlier this month found. “We are doing very few objective tests of these and many other creative interventions,” says Bruno. “Tests being done are nearly always by their advocates and other people with financial interests in them.” Scientists including Meredith have previously argued that research into geoengineering, such as blocking the sun with aerosols or building seabed curtains to protect glaciers, can be “environmentally dangerous”. Sea temperatures higher than we have ever seen, however, will provide a “natural lab” to test geoengineering techniques that target small patches of ocean, rather than entire regions or the entire planet, he says. “It’s a window into the future and how well these schemes might work in future,” says Meredith. But Daniela Schmidt at the University of Bristol in the UK says geoengineering tests could make the damage done by El Niño even worse. “We don’t know, and if we don’t know… I still prefer the precautionary principle,” she says. Schmidt adds that short-term actions can’t make up for the lack of long-term solutions like cutting fossil fuel emissions and expanding marine protected areas, as the article also notes. “Go to the coral reefs, take bits, keep them in the lab,” she says. “But that doesn’t give you a reef back if that reef dies in a year’s time.” Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.2623156123