The climate pattern driving El Niño has grown 36 percent more intense over the past four decades compared to pre-industrial times as global temperatures rise, according to a comprehensive study published in the journal Science on Thursday.
The findings arrive as a developing Super El Niño gains strength across the tropical Pacific Ocean, with meteorologists expecting the 2026 event to become the most powerful climate phenomenon of its kind since at least 1950 and potentially much earlier.
Researchers discovered that El Niño events during the last 40 years were also roughly 16 percent more intense than those recorded throughout the 20th century. The increase represents a sharp departure from natural climate variation observed over the past 1,000 years.
Galapagos corals record ocean chemistry
The study relies on historical temperature records preserved in living corals and ancient coral fossils collected from the Galapagos Islands. Located off the coast of Ecuador in the eastern tropical Pacific Ocean, the islands sit in a critical region where El Niño conditions form and intensify.
Julia Cole, the lead author of the study and a professor of earth and environmental sciences at the University of Michigan, described corals as the time machines of the sea.
She explained that corals preserve a detailed history of their growth conditions within the chemical composition of their skeletons. Scientists extracted this climate record by measuring the ratios of specific isotopes in core samples drilled from reef structures.
By analyzing these coral cores, the research team reconstructed ocean temperature fluctuations spanning a millennium. The data revealed that recent El Niño events differ dramatically from those during the 1,000 years preceding the Industrial Revolution, when human industrial activity began producing massive amounts of greenhouse pollution.
Disrupted tropical climate systems
The team examined climate shifts starting from the major Super El Niño of 1982 to 1983 through modern events. They concluded that the Pacific climate system has been fundamentally disrupted and is no longer functioning as it did historically.
Jonathan Overpeck, a co-author of the study and dean of the School for Environment and Sustainability at the University of Michigan, said that something highly unusual is occurring in the Pacific Ocean that is very likely caused by human-driven climate change.
To determine whether natural climate variability could explain the changes, the researchers combined their 1,000-year coral reconstruction with data from an ensemble of 12 state-of-the-art climate models. The modeling results allowed scientists to rule out natural cycles as the main cause of recent El Niño strengthening.
Although the study stops short of a formal attribution linking the intensification directly to human activity, the authors noted that global warming is the most probable explanation. They emphasized that additional research is necessary to establish a definitive cause-and-effect relationship.
The new paper adds to a growing body of scientific evidence indicating that human-induced climate change is altering the core characteristics of the El Niño phenomenon.
Pacific ocean dynamics and global impacts
El Niño events occur when sea surface temperatures in the equatorial tropical Pacific Ocean rise significantly above normal levels, accompanied by major shifts in atmospheric circulation across the region.
These warm-water events raise global average surface temperatures and alter weather patterns around the globe, often triggering severe droughts, torrential rainfall, and extreme weather events on multiple continents.
The data shows that oscillations between El Niño and its cooler sister phenomenon, La Niña, are growing wider in amplitude. Researchers attribute this expanding swing to the climate cycle leaning more heavily toward more intense El Niño phases.
Kim Cobb, a coral researcher at Brown University who was not involved in the research, described the study as a timely and important contribution to understanding how global warming affects El Niño intensity.
She praised the study as being close to a gold standard in climate reconstruction, noting that the researchers selected the right natural archive in the exact location where El Niño exerts its greatest impact.
Cobb added that while scientists wait to evaluate the full magnitude of the 2026 El Niño, the new findings provide strong evidence that human-caused global warming accounts for part of the event's record strength.
The ongoing warming during the 2026 El Niño is outstripping nearly all historical events on record, altering global weather conditions and driving extreme weather patterns worldwide.
Threats to coral reefs and vanishing data
The ocean warming associated with intense El Niño events, combined with long-term global temperature increases, threatens to destroy the very corals that provided the historical data.
Corals thrive within a narrow temperature range. When water temperatures exceed normal limits, corals experience thermal stress and expel the microscopic algae that supply their vibrant colors and nutrients.
This expulsion leaves the coral skeletons stark white in a process known as coral bleaching. If elevated water temperatures persist over extended periods, the bleached corals starve and die.
Global coral bleaching events have previously coincided with major El Niño episodes, including the Super El Niño of 2015 to 2016. Scientists fear another severe mass bleaching event will strike reef systems this year.
As a result, researchers like Cole are engaged in an urgent race against time to collect coral core samples before healthy reef ecosystems disappear.
Cole compared their work to that of glaciologists who are hurrying to extract ice cores from rapidly retreating mountain glaciers before the ice record melts away.
