A Pacific El Niño is setting daily warm water records. Scientists say the world is in uncharted waters and they aren't sure what will happen next.Show Caption
The world's most influential climate pattern is baring its teeth in the Pacific.The strengthening El Niño – a natural warming of seawater that influences weather around the planet – is setting daily warm water records.It's not only "very likely to be the strongest event since reliable records began – it may end up the strongest by a truly mind-blowing margin," Zeke Hausfather, a research scientist at Berkeley Earth, wrote in a post for The Climate Brink, a Substack blog, earlier in July.It remains to be seen what this will mean for the world's weather over the next 12 to 18 months, but climate scientists say El Niño's effects on global temperatures will increase the chances that 2026 could be the warmest year on record, and make it likely that 2027 will be the warmest.Meanwhile, world leaders have expressed concern about the prospect of droughts, heavy rainfall events and heat waves. (It's worth noting, however, that not El Niño effects are sinister. The climate pattern is widely expected to tame the 2026 Atlantic Hurricane season.)El Niño impacts are already being felt in the U.S., suppressing Atlantic hurricane activity and bringing unusual heat and humidity to parts of California, one of the states most vulnerable to El Niño’s impacts.Sea surface temperatures already have crossed the threshold that typically marks a very strong event, Hausfather and Robert Rohde, his colleague at Berkeley Earth, wrote in a monthly climate briefing on July 23.The warming trajectory of sea surface temperatures in the El Niño region along the equator has been “remarkable,” developing faster than the 1997-98 El Niño, Hausfather wrote in the earlier post.NOAA data shows water temperatures in the region have never run this hot in July in the modern record.Why scientists are worriedWhile El Niño is a naturally occurring pattern, concerns are growing about its amplified impacts when combined with the climate change-fueled warmer-than-normal temperatures around the globe.The world is looking at "an unprecedented combination" between the strong El Niño and the elevated warmth from climate change, said Daniel Swain, a climate scientist with the University of California Agriculture and Natural Resources. That will influence what El Niño actually means on the ground in the U.S. and across the world, Swain said.Previous El Niño events temporarily raised global temperatures about 0.54 degrees Fahrenheit, he said. Now the globe will have the effects of long-term human-caused warming with additional warming on top of that."A potentially record-breaking El Niño on top of record-breaking global temperatures to begin with is a pretty big deal," he said."The odds of either this year or next year, or both, setting a new record warm average global temperature are high," Swain said. “If we don’t get there this year, we almost certainly will next year.”Sea surface temperatures in the El Niño region of the Pacific are up to 6 degrees warmer than normal for the date, a phenomenon that is several times more likely because of climate change, according to Climate Central, a nonprofit climate science and communications organization."What is most striking is how strong this event is forecast to become," wrote Hausfather and Rohde in their briefing. The vast majority of computer models predict an El Niño that exceeds the 2015-2016 record event, even taking into account the background ocean warming, the pair concluded. It's "more likely than not to be the strongest El Niño ever observed."What can we expect in El Niño impacts?A "very strong" El Niño can influence weather worldwide."El Niño will give an extra boost to global temperatures,” stated Alvaro Silva, a World Meteorological Organization scientist. “We know that during El Niño years, the global temperatures normally reach record levels.”In the U.S., a strong El Niño means “a pretty robust increase in the jet stream,” Swain said. “That can result in more intense and more frequent winter storms in California, the interior southwest and the southern tier of states.”“Some of California’s wettest winters have occurred during some of the strongest El Niños," he said.El Niño can heighten hurricane activity in the eastern Pacific and suppress hurricane activity in the Atlantic.Because of its influence on hydrologic cycles, El Niño can bring catastrophic floods to some regions but severe drought and wildfires to others. It can also disrupt fisheries and food production and bring about trillions of dollars in economic losses."The current forecasts imply this could be the costliest El Niño on record," Justin Mankin, a Dartmouth geography associate professor who studies El Niño's economic impacts, recently told USA TODAY by email.Specifically, there are likely to be drier-than-average conditions in Central America and the Caribbean, along with North and South America, the United Nations said. Drier weather patterns are also forecast in parts of Indonesia and Southeast Asia during the monsoon season, but wetter conditions are anticipated during the rainy season from September to December in East Africa.Uncertainties remain about El Niño forecastEven though the signals and models point to a strong El Niño, that doesn't mean it will definitely be the strongest on record when it's expected to peak later this year, said climate scientist Michael Mann, director of the Penn Center for Science, Sustainability & the Media at the University of Pennsylvania.“It’s clear we are headed towards an historically strong event,” Mann said, but "there’s still a variety of scenarios we could see."El Niño is intrinsically a chaotic event in a climate system that doesn’t always respond in simple, proportional ways, Mann explained. Its greatest impacts come from its connections to the larger atmosphere, such as the trade winds and upper atmospheric winds, but those teleconnections can be hard to predict.Small differences in conditions such as ocean temperatures or the trade winds can alter what happens later. For example, El Niño's ultimate impacts depend on factors such as where the maximum heating takes place in the equatorial Pacific in the fall and early winter.Part of the uncertainty rests with the fact that the models are in "uncharted waters,” Hausfather wrote. The models have "never been verified in this territory."It’s unusual to see this kind of agreement among the strongest predictive models, but what that will mean remains to be seen, Swain said. “Every event has a different flavor and this will undoubtedly have a different flavor than we’ve ever seen before.”Dinah Voyles Pulver and Doyle Rice are national correspondents with USA TODAY who have decades of experience writing about weather and climate. Reach them at dpulver@usatoday.com and drice@usatoday.com.
