‘Normal was left in the dust’: El Niño may return this year and make the planet even hotter
‘Normal was left in the dust’: El Niño may return this year and make the planet even hotter
Concerns are mounting about global temperatures reaching new peaks, as experts predict the potential return of El Niño this year. The US National Oceanic and Atmospheric Administration (NOAA) estimates a 50 to 60 per cent probability of the phenomenon developing between July and September, with a 60 per cent likelihood of shifting from La Niña to ENSO-neutral by February-April. However, model uncertainty remains “considerable,” as early-season forecasts tend to be less reliable.
The Pacific’s climatic rhythm
El Niño and La Niña represent contrasting climate patterns in the Pacific Ocean, influencing weather systems worldwide. During typical conditions, trade winds move from east to west, directing warm surface waters toward the western Pacific. When El Niño occurs—Spanish for “the boy”—these winds weaken or reverse, causing the eastern Pacific to retain more heat. Conversely, La Niña (the girl) sees stronger trade winds, pushing warm waters further west and allowing colder depths to rise, lowering temperatures in the Americas.
El Niño events are irregular, happening roughly every two to seven years, and usually last about a year, though they can extend longer. They often follow La Niña, creating a cyclical pattern. “El Niño tends to suppress rainfall over most tropical land,” says Kieran Hunt, a climate scientist at the National Centre for Atmospheric Science. “This means, all other things being equal, that the Asian, African and South American monsoons tend to be drier than usual. It is also associated with increased rainfall and occasional flooding in the southern United States, Peru, Argentina, southern Europe, Kenya and Uganda.”
A shifting baseline
The old method of tracking El Niño and La Niña relied on comparing temperatures to 30-year averages in three tropical Pacific regions. An El Niño was defined as 0.5 degrees Celsius warmer than normal, while La Niña saw a similar cooling. But as heat-trapping gases intensify, what scientists consider “normal” has evolved. NOAA has now introduced a new index to reflect this change, comparing temperatures to the rest of Earth’s tropics instead.
Recent differences between the old and new systems have reached up to half a degree Celsius, according to Nat Johnson, a meteorologist at NOAA’s Geophysical Fluid Dynamics Lab. “That’s enough to have an impact,” he says. This adjustment may lead to fewer El Niños and more La Niñas than previously recorded. “When El Niño develops, we’re likely to set a new global temperature record,” adds Jennifer Francis of the Woodwell Climate Research Center. “’Normal’ was left in the dust decades ago. And with this much heat in the system, everyone should buckle up for the extreme weather it will fuel.”
