Scientists Update El Nino Labeling as Climate Change Alters Cycle

New research shows how the natural El Nino-La Nina cycle is being shaped by global warming, leading to more frequent and intense weather events.

Published on Feb. 21, 2026

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Scientists have had to update how they label the El Nino and La Nina weather patterns due to rapid changes caused by global warming. Increasingly hot waters globally have caused the U.S. National Oceanic and Atmospheric Administration to alter how it calculates when the cycle has flipped, likely meaning more events will be considered La Nina and fewer will qualify as an El Nino. Researchers also found that the unusual recent twist in the warming and cooling cycle, including an unusually long La Nina period, can help explain the spike in global temperatures over the past three years.

Why it matters

The El Nino-La Nina cycle has major impacts on weather patterns worldwide, influencing everything from hurricane activity to drought. As climate change alters this natural cycle, it will have significant implications for extreme weather events and their effects on communities around the globe.

The details

The U.S. National Oceanic and Atmospheric Administration has updated how it defines and labels El Nino and La Nina events, moving to a more relative index that compares tropical Pacific temperatures to the rest of the Earth's tropics. This is because what's considered "normal" has been shifting rapidly due to global warming, with the waters getting so warm that the old definitions no longer accurately captured the atmospheric interactions. The new method will likely mean more La Nina and fewer El Nino events being labeled. Separately, a new study found that an unusually long, three-year La Nina period, combined with long-term human-caused climate change, can help explain the spike in global temperatures over the past few years, as the La Nina trapped more heat on Earth.

  • In early 2023, Earth's average monthly temperature took a noticeable jump up from the long-term upward trend connected to human-caused climate change.
  • This temperature increase continued through 2025.
  • NOAA updated its El Nino/La Nina definitions this month to a more relative index.

The players

NOAA

The U.S. National Oceanic and Atmospheric Administration, the government agency that monitors and studies the environment, including weather patterns like El Nino and La Nina.

Yu Kosaka

A climate scientist at the University of Tokyo and co-author of the study on how the El Nino-La Nina cycle is being shaped by global warming.

Jennifer Francis

A scientist at the Woodwell Climate Research Center who commented that the research on the El Nino-La Nina cycle and global temperature spike makes sense.

Nat Johnson

A meteorologist at NOAA's Geophysical Fluid Dynamics Lab who explained the agency's updates to how it defines and labels El Nino and La Nina events.

Tom Di Liberto

A former NOAA meteorologist who is now with Climate Central and explained the relationship between La Nina and El Nino events and global temperatures.

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What they’re saying

“When there is a transition from La Nina to El Nino, it's like the lid is popped off, releasing the heat.”

— Tom Di Liberto, Former NOAA Meteorologist (Climate Central)

“If our body's temperature is high then it tends to emit its energy out, and the Earth has the same situation happening. And as the temperatures increase, it acts to emit more energy outward. And for three-year La Nina, it's opposite.”

— Yu Kosaka, Climate Scientist (University of Tokyo)

“When El Nino develops, we're likely to set a new global temperature record. '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.”

— Jennifer Francis (Woodwell Climate Research Center)

What’s next

NOAA's forecast is for an El Nino to develop later this year in the late summer or fall. If it comes early enough, it could dampen Atlantic hurricane activity, but it would also mean warmer global temperatures in 2027.

The takeaway

As climate change continues to alter the natural El Nino-La Nina cycle, it will have significant implications for extreme weather patterns and global temperatures. Scientists are having to constantly update how they define and monitor these events to keep up with the rapid changes, underscoring the need for continued research and adaptation to the impacts of a warming world.