What does the Science study of nearly 1,000 years of Galápagos coral records find about how human-caused warming has affected El Niño strength and variability—including the reported 36% increase since preindustrial times and 16% rise over the past 40 years, the proposed warming–E

The study’s central finding is that recent eastern-Pacific El Niño variability is unusually large in a millennium-long Galápagos coral record and is consistent with human-driven warming amplifying El Niño—not simply raising the ocean’s background temperature. It supports a serious near-term risk from the 2026–27 event, but it does not make a record-breaking outcome certain or establish that every individual El Niño is caused by climate change. 12

• What the corals show: Chemical temperature signals in modern and fossil Galápagos corals indicate that El Niño–Southern Oscillation (ENSO) variability over the past 40 years is about 36–37% greater than in the preindustrial period and roughly 16% above the preceding 40-year interval—an acceleration rather than a uniform long-term trend. 23

• Interpretation: The study finds a strong correspondence between warmer global conditions and larger eastern-tropical-Pacific temperature swings. The proposed mechanism is an amplifying loop: greenhouse warming increases the likelihood or amplitude of warm eastern-Pacific anomalies; strong El Niños then alter clouds, winds, ocean circulation, and global heat distribution in ways that can temporarily add to global warming and intensify climate impacts. This is a physical hypothesis supported by the record, not proof of a simple one-way, deterministic cycle. 12

• Key caveats: ENSO is intrinsically chaotic, with large natural variation across decades and centuries; a coral archive is also a regional proxy, strongest for the eastern-Pacific expression of El Niño. Models have historically disagreed on precisely how ENSO frequency, location, and amplitude respond to warming. Thus, the finding strengthens the case that warming is amplifying ENSO variability, but it cannot attribute the exact strength of a particular event—or guarantee a monotonic future increase—to emissions alone. 145

• 2026–27 forecast: Seasonal forecasts assessed by the European Commission’s Joint Research Centre found El Niño in 2026 virtually certain and assigned a very high likelihood that it would be very strong, potentially unprecedented. U.S. forecasting reported more than a 90% chance of a very strong event in late 2026/early 2027, while the probability of exceeding the historical record was lower; these are probabilities, not predictions of certainty. 67

• Potential consequences: A powerful El Niño shifts weather patterns globally, increasing the risk of drought and heat in some regions and heavy rain, flooding, and landslides in others. Crop losses, disrupted fisheries, damaged infrastructure, commodity-price pressures, and reduced labor productivity can transmit into global economic costs. WFP projected that a strong event could put 49 million additional people at risk of acute hunger, with Central America and southern Africa among the most exposed regions. 78

• Policy implication: The appropriate response has two tracks:

  • Adapt now: strengthen forecast-based early action, food reserves and cash support, drought-tolerant agriculture, water management, flood defenses, health surveillance, and disaster preparedness in high-risk places.
  • Cut fossil-fuel emissions rapidly: adaptation reduces harm from the El Niño already underway; mitigation limits the longer-run warming that the coral evidence suggests may be loading the odds toward more extreme ENSO swings. 12

The clearest takeaway is risk management: a warming world may be making an already unpredictable climate oscillation more volatile, so governments should not wait for absolute certainty before preparing for a severe 2026–27 event and reducing the emissions that raise future risk.