Meteorologists say the natural El Nino cycle, which shapes global weather, is both influencing and being influenced by a warming planet.

A new study suggests an unusual recent shift in the El Nino–La Nina cycle may help explain why Earth’s already rising temperature jumped sharply over the past three years. At the same time, scientists have revised how El Niño and La Niña are defined because rapid climate change is altering ocean conditions. Persistently hotter global waters led the U.S. National Oceanic and Atmospheric Administration (NOAA) this month to change how it determines when the cycle shifts, likely resulting in more events labeled La Niña and fewer classified as El Niño despite warming tropical seas.

Brain organoids show goal-directed learning in control task

Earth’s average monthly temperature rose markedly above the long-term human-caused warming trend in early 2023 and continued through 2025. Possible causes include faster greenhouse gas warming, reduced ship pollution, an underwater volcanic eruption and increased solar output.

A Nature Geoscience study by Japanese researchers found Earth’s “energy imbalance” — the gap between incoming and outgoing energy — increased in 2022, trapping more heat and raising temperatures. About three-quarters of this change was linked to long-term climate change combined with a shift from a three-year cooling La Niña to a warm El Niño phase.

El Niño is the natural warming of parts of the equatorial Pacific that alters global weather, while La Niña features cooler waters. El Niño generally boosts global temperatures, while La Niña suppresses the long-term rise and can worsen U.S. hurricanes and drought. From 2020 to 2023, Earth experienced an unusual “triple dip” La Niña, trapping extra heat. About 23% of the recent energy imbalance came from this prolonged event, while slightly over half came from fossil-fuel greenhouse gases.

Rare smiling fossil found on Holy Island

Because “normal” temperatures keep shifting, NOAA replaced its old 30-year baseline with a relative index comparing Pacific temperatures to the rest of the tropics, improving atmosphere–ocean interaction tracking. NOAA forecasts another El Niño later this year, which could curb Atlantic hurricanes but push global temperatures higher in 2027 and possibly set a new record.