El Ninos are now stronger than any in the past 1,000 years, study finds

El Niño events have become nearly 40% stronger over the past four decades than at any point in the previous millennium, according to a study published Thursday in the journal Science that offers some of the clearest evidence yet linking human-caused climate change to the intensification of the world's most powerful natural climate cycle.eurekalert+1

The research, led by Julia Cole, professor and chair of the University of Michigan Department of Earth and Environmental Sciences, draws on a 1,000-year temperature record extracted from living and ancient corals in the Galápagos Islands — located at the epicenter of El Niño's formation in the eastern tropical Pacific.scientificamerican+1

"Our findings tell us that the big El Niño events of the last 40 years are not normal in the context of the last thousand years," Cole said in a statement.eurekalert

A Thousand Years Written in Coral

The team sampled 13 corals, analyzing the ratio of strontium to calcium and oxygen isotopes in their skeletons to reconstruct sea surface temperatures month by month across scattered windows of the past millennium. The data showed that variability in the El Niño-Southern Oscillation cycle has increased by roughly 36.5% in the eastern Pacific compared with the pre-industrial era, driven largely by more intense El Niño events.newscientist+1

Using 12 climate models simulating the last thousand years, the researchers ruled out natural causes such as volcanic eruptions or solar variability as explanations for the shift.cnn+1

"Something is going on now that is highly unusual and very likely due to human-caused climate change," said study co-author Jonathan Overpeck, dean of the University of Michigan's School for Environment and Sustainability.cnn

Implications for a Strengthening Super El Niño

The findings arrive as a super El Niño is gathering strength in the tropical Pacific. The National Oceanic and Atmospheric Administration's Climate Prediction Center has said there is a 69% chance the current event will exceed the strength of all previous El Niños dating back to 1950. Sea surface temperatures in the east-central Pacific are projected to reach 4°C above normal when the event peaks later this year.usatoday+1

Kim Cobb, director of the Institute at Brown for Environment and Society, called the study's coral reconstruction "close to the gold standard" and described it as "a critical piece of the puzzle" in understanding how warming alters El Niño.scientificamerican+1

Not all experts are fully convinced. Michael Mann of the University of Pennsylvania gave the study a mixed review, noting gaps in the coral record and arguing that volcanic eruptions may play a larger role than acknowledged.usatoday

Racing Against Disappearing Evidence

The study also highlights a cruel irony: the warming ocean waters amplifying El Niño threaten to destroy the very corals that provided these insights. Scientists are racing to collect samples before mass bleaching events — already linked to recent super El Niños — eliminate the archive.cnn

"As we pile up the evidence for a fossil fueled-intensification of El Niño, we contemplate a future of worsening El Niño-related weather and climate extremes on top of a baseline of worsening weather and climate extremes," Cobb said. "This would have massive implications for communities and ecosystems around the world."cnn