The rhythm of Earth's climate may change completely. A joint team from Korea, the United States, Germany, and Ireland announced findings that global warming could fundamentally alter the Pacific's El Niño and La Niña phenomena.
The Institute for Basic Science (IBS)-led international team said in the journal Nature Communications on 16th that "if humanity's greenhouse gas emissions continue, the El Niño–Southern Oscillation (ENSO), a key driver of Earth's climate variability, could evolve over the next few decades into a much stronger and more regular form."
ENSO refers to a global climate phenomenon in which sea surface temperatures and atmospheric pressure in the eastern Pacific fluctuate periodically. It is divided into El Niño, a phase with sea surface temperatures higher than average, and La Niña, a phase with lower temperatures. The terms come from Spanish meaning "boy" and "girl," respectively, and both have a major impact on Earth's climate.
The researchers used an ultra–high-resolution climate model to simulate climate change through the end of the 21st century. As a result, they projected that the currently irregular, recurring El Niño and La Niña cycle could shift within the next 30–40 years into a "regular oscillation" with a fixed period.
At the same time, sea surface temperature swings are expected to grow much larger than today. Warming strengthens atmosphere–ocean interactions and increases weather variability in the tropics, thereby amplifying both the intensity (amplitude) and regularity of ENSO.
Malte F. Stuecker of the University of Hawaii said, "In a warmed world, enhanced interactions between the atmosphere and ocean can turn the system unstable, producing large oscillations from small perturbations," adding, "this is the first time such a transition has been identified in a complex climate model."
The team also noted that a strengthened ENSO could synchronize with other major climate systems. If multiple systems such as the North Atlantic Oscillation (NAO), the Indian Ocean Dipole (IOD), and the tropical North Atlantic (TNA) mode become interlocked, climate patterns around the world could shift simultaneously.
Axel Timmermann, Director General of the IBS Center for Climate Physics, said, "This is similar to multiple pendulums gradually swinging in the same rhythm," warning that "this could intensify the 'hydrological whiplash'—alternating extreme droughts and deluges—in places such as Southern California and the Iberian Peninsula."
The researchers also validated the results by analyzing other climate models and actual observations. Sen Zhao, a researcher at the University of Hawaii, explained, "Some other models show similar results, and while the future of El Niño may become more predictable than now, its impacts could grow much larger."
Director General Timmermann said, "If El Niño becomes more regular, ENSO forecasts could become more accurate," adding, "but at the same time, the impacts on agriculture, ecosystems, and water resources—and on human life overall—will intensify. A global-level response is now necessary."
Going forward, the team plans to use Aleph, IBS's first supercomputer, to further analyze synchronization in Earth's climate system with higher-resolution climate models.
References
Nature Communications (2025), DOI: https://doi.org/10.1038/s41467-025-64619-0