El Niño events have grown nearly 40% stronger in the last four decades compared to the preceding thousand years, according to new research. Scientists analyzing coral samples from the Galapagos Islands have determined that current El Niño events surpass those of the past millennium in intensity.
"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 study involved examining core samples from 13 corals in the Galapagos, some of which were ancient and others living colonies. Researchers focused on samples spanning at least 20 years, as El Niño events occur every few years. The analysis revealed a pattern of strong El Niños in the last 40 to 50 years, contrasting with a "pretty consistent pattern of lower intensity El Niños" prior to that period.
Scientists used climate models to simulate the past 1,000 years, incorporating data on volcanic eruptions and solar variability. The models did not find evidence that natural processes alone could explain the observed increase in El Niño strength, suggesting that global warming is a significant contributing factor.
The El Niño Southern Oscillation (ENSO) is a naturally occurring climate cycle that alternates between warm El Niño phases and cool La Niña phases approximately every two to seven years. During an El Niño phase, the trade winds across the Pacific weaken or reverse, leading to a buildup of warm water off the west coast of South America. This can elevate global average temperatures and disrupt weather patterns worldwide.
"El Niño is a really big source of climate extremes, and so if it's getting stronger, the impacts are getting stronger," Professor Cole explained. "Impacts like droughts, floods, wildfire and food insecurity. 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."
Experts warn that the current El Niño event is on track to be one of the most powerful on record. While ENSO is a natural phenomenon, the study suggests that global warming is exacerbating its intensity. "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," Professor Cole stated. "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."