Scientists are revising how they label El Niño and La Niña weather patterns to account for rapid global temperature spikes. These natural cycles, which influence weather worldwide, are now interacting with a warming planet in unprecedented ways.
A new study in Nature Geoscience attributes a significant portion of Earth's recent temperature surge to the combination of long-term human-caused climate change and a shift from a cooling La Niña to a warming El Niño phase. This "energy imbalance" means more heat is being trapped on Earth.
El Niño is characterized by a warming of equatorial Pacific waters, altering global weather, while La Niña signifies cooler waters. Historically, La Niñas tend to depress global temperatures, while El Niños increase them.
From 2020 to 2023, an unusual "triple dip" La Niña occurred without an intervening El Niño. Researchers suggest this extended cooling period trapped extra energy, making the subsequent transition to El Niño more impactful.
To keep pace with these changes, the US National Oceanic and Atmospheric Administration (NOAA) has updated its methodology for identifying El Niño and La Niña events. Previously based on fixed temperature differences in tropical Pacific regions, the new system uses a relative index comparing current temperatures to the rest of the Earth's tropics. This adjustment is expected to result in more events being classified as La Niña and fewer as El Niño.
NOAA forecasts an El Niño developing later this year. Experts warn that with the current excess heat in the system, the world should prepare for intensified extreme weather events.