El Niño events 40% stronger in past 40 years than pre-industrial era, study finds

A Coral Record of El Niño's Past

A study published in the journalScience has found that El Niño events during the past 40 years have been nearly 40% stronger than those of the pre-industrial era, and stronger than any seen in the previous 1,000 years. The research, led by Julia Cole of the University of Michigan, examined cores from 13 modern and ancient corals in the Galápagos Islands, where the chemistry of the coral preserves clues about historical seawater temperatures.

The team found that strong El Niños have become especially prominent over the past four to five decades, whereas earlier events showed a "pretty consistent pattern of lower intensity." According to Cole, "We don't see a time in the past where El Niños have been as strong as today, and we show that the strength of El Niño changes in parallel with the warming of global temperature."

Cole, a professor and chair of the University of Michigan's department of earth and environmental sciences, added, "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."

The Role of Global Warming

The researchers also analysed climate models simulating the last thousand years with histories of volcanic eruptions and solar variability. The models found no large shifts in El Niño that suggested natural processes could create such large changes. Instead, the study attributes the intensification to global warming driven by fossil fuels.

"We believe global warming is supercharging El Niño, and if that's true, then we expect stronger climate extremes that will amplify ecological, infrastructural and human losses," Cole said, adding, "No country has the resources to be fully protected from these impacts. This is one more reason we need to move away from fossil fuels, the root cause of the problem."

Implications for Extreme Weather

El Niño is a recurring warming of the tropical Pacific that can shift winds, rainfall and temperatures far beyond the ocean where it begins. Its effects can include droughts as well as rain, floods, wildfires and food insecurity. Cole noted, "El Niño is a really big source of climate extremes, and so if it's getting stronger, the impacts are getting stronger. Impacts like droughts, floods, wildfire and food insecurity."

She also highlighted broader consequences: "Changes in the hydrologic cycle also lead to issues like damage to infrastructure: floods that wipe out homes, highways or railroads, or to health effects, such as diseases like cholera."

Current El Niño and Forecasts

The study comes as the current El Niño unfolds. In June, the India Meteorological Department (IMD) confirmed El Niño and expected it to strengthen during the monsoon; Japan's Meteorological Agency had declared it a day earlier. India's June rainfall ended nearly 40% below normal and has been deficient since. Despite a possible positive Indian Ocean Dipole (IOD) offering some hope of cushioning the impact, the deficit persisted.

Global weather and climate agencies have forecast the 2026-27 El Niño with a greater than 90% chance to reach "very strong" or near-record levels. "The question is not whether the current El Niño is going to happen, but how bad is it going to be, and how bad will the impacts be?" Cole said.

She added that this event is superimposed on global warming, and it's likely to supercharge the temperature increase that we would normally see from greenhouse gases. There are forecasts that temperatures could reach 1.7 or 1.8 degrees Celsius above pre-industrial levels.

Expert Perspectives

Dr. Julia Cole, lead author, University of Michigan: The study's findings indicate that recent El Niño strength is unprecedented in the last millennium and is linked to global warming. Cole emphasized the seriousness of the situation, stating, "We don't see a time in the past where El Niños have been as strong as today," and warned of intensified climate extremes and the need to move away from fossil fuels.

India Meteorological Department (IMD) and Japan's Meteorological Agency: Both agencies declared the current El Niño in June, with the IMD expecting it to strengthen during the monsoon. Their declarations align with the study's context of stronger El Niño events, though neither agency is directly quoted on the study's findings.

Global weather and climate agencies: Forecasts cited in the study indicate a greater than 90% chance that the 2026-27 El Niño will reach "very strong" or near-record levels, underscoring the potential for severe impacts.