El Niño events have intensified by nearly 40% in the last 40 years compared to the preceding millennium, according to a new study that examined coral from the Galapagos Islands. Scientists believe global warming is a primary driver of this increased strength.
"We don't see a time in the past where El Niños have been as strong as today," said lead author Professor Julia Cole of the University of Michigan. "We show that the strength of El Niño changes in parallel with the warming of global temperature. 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 research analyzed core samples from 13 corals, some dating back centuries. The El Niño Southern Oscillation (ENSO) is a natural climate cycle that shifts between warm El Niño phases and cool La Niña phases every two to seven years. During El Niño, trade winds in the Pacific weaken or reverse, causing warm surface water to accumulate off the coast of South America. This warmer water can raise global temperatures and disrupt weather patterns.
The study found a consistent pattern of lower-intensity El Niños prior to the last 40 to 50 years. "We kept adding records thinking well, this is going to get more complicated, but it really didn't," Professor Cole stated. "This is such a clear story."
To investigate the reasons for the intensification, researchers used climate models that simulated the past 1,000 years, incorporating data on volcanic eruptions and solar variability. The models did not find evidence that natural processes alone could account for the significant changes observed in El Niño strength, leading the researchers to attribute the trend largely to global warming.
Professor Cole noted that stronger El Niños can lead to more extreme weather events, such as droughts, floods, wildfires, and food insecurity. These disruptions can also impact infrastructure, causing damage to homes, highways, and railroads, and can affect public health through the spread of diseases like cholera. "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," she said. "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."
The current El Niño event is on track to be one of the most significant on record. Experts have warned of potential severe weather impacts, with some predicting mild, stormy conditions in Britain during autumn and early winter, potentially followed by colder temperatures. ENSO's phases, El Niño (warm phase), La Niña (cool phase), and neutral, influence global temperature, winds, and precipitation patterns.