After months of unprecedented climate impacts, one of the five strongest El Niño events on record could start to weaken between March and May, says the World Meteorological Association (WMO).
El Niño peaked in December, but the weather pattern will leave lingering impacts in the coming months, “fuelling the heat” trapped by human carbon emissions even as it gives way to neutral conditions, the WMO said in a release.
“Every month since June, 2023 has set a new monthly temperature record—and 2023 was by far the warmest year on record,” said WMO Secretary-General Celeste Saulo. “El Niño has contributed to these record temperatures, but heat-trapping greenhouse gases are unequivocally the main culprit.”
El Niño and its counterpart La Niña are oceanic components of the larger ENSO climate phenomenon that also includes an atmospheric component called the Southern Oscillation. ENSO occurs in three phases—a warm El Niño phase, a neutral phase, and a cooler La Niña phase—that cycle on average every three to five years to influence global weather. El Niño potentially lasts up to 18 months, while La Niña can extend for up to three years.
In El Niño’s off-years, tropical Pacific winds blowing from the east expose cold water along South America’s western coast and push warmer waters to accumulate in the western Pacific. The shift to El Niño happens when those Pacific winds begin to instead blow from the west, causing that warm water to move to the east. The shifting mass of warm water also warms the air, which brings higher temperatures through wind currents, causing climatic changes like more rainfall in some areas and droughts in others, explains Paul Roundy, professor of atmospheric and environmental sciences at the University of Albany, on The Conversation.
This current El Niño period started last June and reached its peak in December, says the WMO. Its tenure was marked by various extreme weather conditions, including serial months with higher-than-ever temperatures that made 2023 the hottest year on record.
It was the first time average global temperatures showed a 1.5°C rise from pre-industrial levels for every month during a 12-month period, from February, 2023 through January, 2024, though scientists were quick to point out that this statistic does not yet represent a breach of the 2015 Paris Agreement, which calls for preventing the temperature rise over a multi-year average.
“Never have we been so close—albeit on a temporary basis at the moment—to the 1.5° C lower limit of the Paris Agreement on climate change,” Saulo said this morning, in a separate release on the WMO State of the Global Climate 2023 report. “The WMO community is sounding the Red Alert to the world.”
The extent of the link between El Niño and climate change, and how those two phenomena may have influenced each other to cause a record hot year, is still uncertain and merits further study, say scientists.
“Last year really was much quicker than we all anticipated,” said Jim Skea, head of the Intergovernmental Panel on Climate Change (IPPC). “Some of it can be explained with the start of an El Niño cycle, which will push temperatures up a bit.”
But “it was still unexpected,” he added. “There’s more science needed to actually understand why 2023 was such a distinctive year.”
With El Niño weakening, the WMO says that after a brief transition to neutral conditions, the climate could shift to El Niño’s cooler opposite number, La Niña, in the latter part of this year, though the odds of that are uncertain.
But even on its way out, El Niño continues to have dire impacts around the globe. In Africa, a drought is withering crops in Zimbabwe, where the government expects that 2.7 million people or more will go hungry this year. And in South Sudan, both climate change and El Niño have been linked to a scorching heatwave that prompted the health ministry to shut down schools to protect students during an anticipated two weeks of temperatures ranging from 41° to 45°C.
The intensity of this El Niño cycle has also been “wreaking havoc” in South America, driving impacts like drought in Bolivia, wildfires in Chile, and a surge of dengue cases amid a heatwave in Peru.
Meanwhile, in North America, Canada experienced a milder-than usual winter, which experts say could lead to a wildfire season even worse than 2023’s record-breaking year.
