Scientists are increasingly concerned that a major El Niño storm is developing. While these natural climate cycles typically recur every two to seven years toward the end of the calendar year, their intensity varies based on prevailing oceanic conditions. El Niño is classified as strong when sea surface temperatures off the west coast of South America exceed the average by more than 1.5 degrees Celsius. According to the US National Oceanic and Atmospheric Administration (NOAA), temperatures in the eastern and central Pacific already rose by over three degrees Celsius this July.
The German Meteorological Service has warned that these conditions could evolve into one of the most powerful El Niño events on record. However, the Max Planck Institute for Meteorology notes that whether climate change will cause strong El Niño events to intensify remains an active area of research, largely due to gaps in historical data.
Reliable satellite measurements of ocean surface temperatures only date back to the 1980s, leaving researchers without clear insights into how El Niño behaved prior to industrialization and widespread fossil fuel use. To bridge this gap, Julia Cole, a climate scientist and paleoclimatologist at the University of Michigan, and her team published a study in the journal Science examining coral records.
“We have long known that the past 40 or 50 years have featured very strong El Niño events,” Cole stated. “It has been difficult to determine whether these recent intensities are part of a natural cycle or something unusual driven by a warmer world.” Her analysis of corals from the Galapagos Islands points clearly to the latter: the current pattern is anomalous.
Corals serve as natural archives, growing between one and two centimeters annually and forming structures analogous to tree rings. As they build their calcium carbonate skeletons, they incorporate chemical signatures from the surrounding water. Cole explained that the ratio of strontium to calcium, as well as isotopes of oxygen, varies with water temperature, allowing researchers to reconstruct ocean temperature changes over the last millennium.
The study concluded that El Niño events have become significantly more intense compared to the pre-industrial period. Jens Zinke, a professor of paleobiology at the University of Leicester, noted that these findings align with predictions from the best climate models, which forecast a higher likelihood of extreme eastern Pacific El Niño events by the 2030s.
Despite these insights, some experts urge caution. Andreas Fink, a meteorology professor at the Institute for Meteorology and Climate Research in Karlsruhe, pointed out that while coral data offers high temporal resolution, its accuracy depends on local conditions, making direct comparisons with modern measurements challenging. He also highlighted the study’s limitation to the eastern Pacific region. Cole acknowledged that her record is not continuous, covering just under half of the years in the last thousand years.
The potential consequences of a “supersized” El Niño are severe, including widespread drought, flooding, and agricultural losses. Countries such as Ecuador and Peru face heavy rains and floods, while Australia and Indonesia may suffer from rain deficits leading to wildfires. Additionally, El Niño contributes to temporary global temperature increases.
Thomas Felis, who leads the coral paleoclimatology group at the MARUM Center for Marine Environmental Sciences at the University of Bremen, warned that if this El Niño reaches super-strong status, 2027 is likely to see another year of record heatwaves. Such heat poses a direct threat to coral reefs, which rely on symbiotic algae for energy. When water temperatures rise excessively, the algae produce toxins, causing corals to expel them—a process known as bleaching.
While corals can survive brief periods of bleaching, prolonged stress leads to death. Felis noted that the El Niño years of 2023–24 and 2015–16 already triggered global coral bleaching events. The loss of coral reefs would not only destroy a vital ecosystem but also erase a critical historical archive of oceanic climate data.
Record heatwaves in 2027 sound scary. Hope this pushes governments to act faster on emissions before reefs disappear entirely.
I wonder if the study’s limited geographic focus skews the results? Eastern Pacific corals might not tell the whole story.
This coral data is sobering. The link between industrialization and these intensifying storms feels undeniable now.