A study published Thursday in the journal Science reports that El Niño events have become more intense over the last 40 years. Researchers found that these climate patterns have become 36% stronger compared to the period before the industrial revolution and 16% stronger than those in the 20th century.
The research team, led by Julia Cole of the University of Michigan, analyzed chemical signatures in living and ancient coral samples from the Galápagos Islands. Because corals preserve a history of ocean conditions in their skeletons, the team was able to reconstruct a 1,000-year history of the El Niño-Southern Oscillation (ENSO) cycle. This historical record was compared against 12 different climate models to evaluate the causes of recent changes.
According to the study, the intensity of El Niño events began to depart significantly from the millennium-long record starting with the 1982-1983 event. While the study stops short of formally attributing these changes solely to human-caused climate change, co-author Jonathan Overpeck stated that the recent shifts are highly unusual and likely linked to human activity. Kim Cobb, a researcher at Brown University not involved in the study, noted that the findings provide evidence that global warming may be contributing to the "chart-topping size" of recent events.
The scale of these events is significant, as a "Super El Niño" developing in the tropical Pacific is forecast to be the strongest recorded since at least 1950. The shift toward more intense El Niños also impacts marine ecosystems. In the eastern Pacific, the weakening of nutrient-rich upwelling during El Niño reduces phytoplankton populations, which are the base of the food web. Conversely, La Niña events, which are the cooler-water counterpart to El Niño, bring different challenges, such as increased hurricane severity in the Atlantic and drought in the southern U.S.
The study also highlights a threat to the scientific record itself; the rising ocean temperatures that fuel stronger El Niño events cause coral bleaching and death. This creates a time-sensitive situation for researchers attempting to collect coral cores before these archives are destroyed. Scientists are currently monitoring the 2026 El Niño, which is already altering global weather conditions. Further research is expected to continue focusing on the specific causal links between human-generated pollution and the shifting ENSO cycle.