The El Niño climate phenomenon helped make 2016 the hottest year on record—and its return later this year could bring even higher temperatures amid "unprecedented heatwaves," scientists say. Forecasters say the pattern in the Pacific Ocean, which affects conditions around the world, is set to flip from La Niña to El Niño, the warmer part of the cycle, making extreme weather worse, the Guardian reports. La Niña and El Niño events tend to develop during the spring and reach peak intensity during the winter before dying down by summer, per IFLScience, meaning any temperature records set in 2023 are likely to be broken in 2024. The cycle has been in the La Niña phase since late 2020.
Scientists say El Niño is likely to bring world temperatures 1.5°C above pre-industrial levels and into territory that climate agreements have sought to avoid. "We know that under climate change, the impacts of El Niño events are going to get stronger, and you have to add that to the effects of climate change itself, which is growing all the time,” says Adam Scaife, head of long-range prediction at the UK Met Office. "You put those two things together, and we are likely to see unprecedented heatwaves during the next El Niño." In the US, El Niño tends to bring hotter and drier weather to northern states and wetter weather to southern states.
"We suggest that 2024 is likely to be off the chart as the warmest year on record," American climate scientist James Hansen said last year, per the Guardian. "Without inside information, that would be a dangerous prediction, but we proffer it because it is unlikely that the current La Niña will continue a fourth year. Even a little futz of an El Niño—like the tropical warming in 2018-19, which barely qualified as an El Niño—should be sufficient for record global temperature." Climate scientist Wenju Cai tells Australia's 9News that with so much heat stored in the equatorial Pacific during three years of La Niña, "an El Niño is readily triggered by relaxation of the trade winds over the region." (Read more El Nino stories.)