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Galápagos corals show El Niño events are more extreme now than in past 1,000 years – here’s how my team made the discovery
Galápagos corals show El Niño events are more extreme now than in past 1,000 years – here’s how my team made the discovery. Originally published by The
By Julia Cole, Professor of Earth and Environmental Science, University of Michigan · 2026-08-31T04:15:11.182Z
A NOAA scientist takes a coral sample in the Galapagos Islands. The process does not injure the colony, which grows back. Atlantic Oceanographic and Meteorological Laboratory NOAA Temperatures have warmed dramatically across the equatorial Pacific Ocean in 2026, signaling the onset of a strong and potentially historic El Niño https://www.cpc.ncep.noaa.gov/products/analysis monitoring/enso advisory/ensodisc.shtml . These events can affect weather around the world, and the intensity of recent El Niño events is raising alarm that, as global temperatures rise https://yaleclimateconnections.org/2026/08/july 2026 ties with july 2024 as earths hottest month on record/ , they are becoming stronger and more destructive https://www.washingtonpost.com/weather/2026/08/13/record el nio could fast forward planets temperature by decade/ . To understand how these climate patterns are changing, we need to understand what happened during El Niño events in the past, but observations go back only a few decades. So, my colleagues and I https://scholar.google.com/citations?user=nR5kaQMAAAAJ&hl=en went to the Galápagos Islands – at the heart of the El Niño pattern – to find answers from some of nature’s best record keepers: corals. In records preserved by living and ancient fossil corals, we found that, on average, El Niño events have been stronger in the past 40 years https://www.science.org/doi/10.1126/science.ady2660 than at any time in the past millennium, with higher temperatures that lead to more powerful effects on weather. That intensification also coincides with human caused global warming. Our results, just published in the journal Science, suggest that the 1982 83 and 1997 98 El Niños – two of the strongest in recent memory – may be harbingers of more extreme events to come http://doi.org/10.1126/science.ady2660 as the planet warms.
Our World in Data, CC BY El Niño comes for the Galapagos One of the strongest El Niños hit in 1982, with devastating consequences for the Galápagos Islands. It triggered a marine heat wave https://www.nytimes.com/interactive/2018/12/18/climate/galapagos islands ocean warming.html that reverberated through one of the most distinctive and unspoiled ecosystems on the planet. Exceptionally warm surface water blocked the usual upwelling of cool, nutrient rich water https://doi.org/10.1038/s41598 020 80609 2 that fuels the food chain for marine life. The result ravaged communities that rely on the ocean https://library.iucn isg.org/documents/1985/Merlen 1985 Noticias de Galapagos.pdf – fish, birds, marine mammals, and people who fish for their livelihoods throughout the eastern tropical Pacific. In the extraordinary heat, more than 95% of Galápagos corals died https://doi.org/10.1016/0025 326X 94 90437 5 . The heat wave was caused by an exceptionally strong El Niño https://oceanservice.noaa.gov/facts/ninonina.html event, part of a climate pattern that begins in the eastern tropical Pacific Ocean, around the Galápagos Islands, as the trade winds shift. El Niño’s warm ocean water alters the atmospheric circulation above, diverting storm tracks and changing patterns of floods, droughts and tropical storms around the globe.
The Galápagos Islands are known for their astounding marine biodiversity, a result of high nutrients and the mixing of cool and warm waters. Greg Asner/DivePhoto.org The 1982 83 El Niño contributed to climate extremes worldwide https://en.wikipedia.org/wiki/1982%E2%80%931983 El Ni%C3%B1o event , from flooding in Kenya and Peru to drought in Indonesia and Brazil, costing the global economy as much as US$4 trillion https://doi.org/10.1126/science.adf2983 by some estimates. A similarly strong El Niño in 1997 98 resulted in 23,000 deaths https://www.theguardian.com/environment/2015/oct/12/el nino could leave 4 million people in pacific without food or drinking water from disease and climate disasters. But we wanted to know: Are such powerful El Niño events unusual in the context of history? Even in 1983, scientists were surprised https://www.washingtonpost.com/news/capital weather gang/wp/2015/06/12/how the super el nino of 1982 83 kept itself a secret/ to find that such a strong event had been underway. Historical records of El Niño are sparse before the era of satellite observations. Fortunately, long lived corals growing in the tropical Pacific can provide a history https://climatedataguide.ucar.edu/climate data/coral geochemical records overview their use climate proxies and available databases of El Niño that extends our view into the past. How corals record history As corals grow, they preserve a record of local ocean temperatures over time. In the Galápagos, because of their location, that record reveals the history of El Niño events and of their cooler counterpart, La Niña. Like trees that produce annual growth rings, corals add skeletal layers of calcium carbonate year after year. The alternating bands of higher and lower density reveal changes in the coral’s growth rate during each year and can serve as a timekeeper. The history of the ocean temperature http://www.science.org/doi/10.1126/science.ady2660 is embedded in the chemical composition of the skeleton itself. To track the history of water temperatures, we measured two chemical parameters – the ratio of heavy to light oxygen isotopes and the ratio of strontium to calcium – both of which reflect the seawater temperature in which the coral grew.
Three sea surface temperature maps show how Pacific Ocean temperatures change between El Niño, La Niña and neutral patterns. The Galápagos Islands are within the small black circle. During El Niño, trade winds weaken, suppressing the upwelling of cool water and allowing temperatures to rise. Temperatures are in Celsius. NOAA In the Galápagos, because of the islands’ location, the sea surface temperature swings between warm El Niño years and colder La Niña years, when upwelling of nutrients is stronger.
The Galápagos Islands sit in a region of strong upwelling, where nutrient rich deep waters rise to the surface. This upwelling results from a combination of the local trade winds and the surfacing of a deep current as it collides with the islands’ mass. The nutrients fuel phytoplankton blooms that provide food for fish, birds and other marine life. Julia Cole, based on original illustration by the Woods Hole Oceanographic Institution
Satellite images of phytoplankton around the Galápagos Islands show how exceptionally warm El Niño events, left, reduce the upwelling of nutrients that phytoplankton need, compared to more normal conditions, right, a few months later. NOAA Climate.gov, based on SeaWiFS data provided by Norm Kuring, NASA GSFC The largest living corals in the Galápagos grow in the northern islands of Wolf and Darwin, in water 20 to 50 feet deep. To study their history http://doi.org/10.1126/science.ady266 , we dived down and took core samples from long lived corals, some 8 to 10 feet tall. Every core we drilled from a living coral showed evidence in its calcified skeleton that the coral had suffered during the 1982 83 El Niño event. We saw obvious “death horizons” – dense layers of calcified material produced by other reef organisms such as algae, gastropods and barnacles interrupting the lattice of the skeleton https://cdhc.noaa.gov/coral biology/coral skeleton/ .
A CT image, left, and photo, right, of a section of coral from Wolf Island shows the ‘death horizon,’ when extreme heat bleached and then killed the corals living there. The coral colony later regrew over the dead surface. We also took samples of fossil corals around the archipelago – mostly dead coral boulders found along the islands’ shorelines. Radiometric dating told us that these fossil corals were up to 4,500 years old. Those samples provide an even deeper view https://doi.org/10.1029/2025GL119006 of El Niño’s history. Back in the lab, we sliced the coral cores lengthwise into slabs and used a drill to extract powdered samples, each representing about one month’s growth, along a path from youngest to oldest. We analyzed the geochemistry of each sample. In the chemical ratios from thousands of samples, we found seasonal cycles spanning many decades and exceptional warm and cold years that revealed a unique history of El Niño and La Niña events.
The Galápagos Islands have many large fossil corals that preserve temperature histories going back millennia. Gerald and Buff Corsi © California Academy of Sciences
A fossil coral in the field shows annual growth bands. Julia Cole A history of ENSO through time emerges Our data show clearly that the strength of the El Niño Southern Oscillation has intensified as global temperatures have warmed. The chemistry of the corals revealed that El Niño events from the past 40 years were stronger than at any other time sampled http://doi.org/10.1126/science.ady266 in the past millennium. The coral data aligns with ocean temperatures measured from thermometers over the past century. But the coral records extend much further back in time, providing long term context to show that modern El Niño events are more extreme than before the industrial era began.
The study found that the strength of El Niño or La Niña paralleled global temperature change over the past millennium. The strength, measured by coral geochemistry, is indicated by the colored circles and triangles: The colors denote the island location, and the shape indicates the type of geochemistry used. Triangles show results derived from the ratio of strontium to calcium, and circles show results from the ratio of oxygen isotopes. The red line indicates the global temperature estimated from other paleoclimate data. Coral data is plotted as the standard deviation of reconstructed Galápagos temperature on left axis, and global temperature data is plotted as deviations from the 1961 1990 average on the right axis. Julia Cole The El Niño intensification we observed, starting in the mid to late 20th century, is also greater than what nearly all climate models suggest would result from natural causes. It appears to be closely connected to human caused global warming – a conclusion in line with expectations from most climate models https://www.nature.com/articles/s43017 023 00427 8 . Not all models anticipate El Niños strengthening https://www.climate.gov/news features/blogs/enso/enso and climate change what does new ipcc report say as the climate warms, but our data shows that unusual strengthening has accompanied recent warming – an association that may allow scientists to identify models that most closely track observations. Looking ahead A stronger El Niño Southern Oscillation means more intense and damaging climate extremes across the globe. If humanity can anticipate those hazards, we can prepare and perhaps avoid the worst damage. Fortunately, scientists understand enough about El Niño and La Niña events today to be able to forecast them up to a year in advance https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml . But such predictions depend on continuous, careful climate measurements from satellites https://sealevel.jpl.nasa.gov/data/el nino la nina watch and pdo/overview/ and buoys across the remote tropical Pacific https://www.pmel.noaa.gov/gtmba/pmel theme/pacific ocean tao , coupled with continuous improvements in climate modeling and forecasting https://www.gfdl.noaa.gov/climate variability and prediction/ capabilities. Those capabilities are now more important than ever as global warming accelerates.
Julia Cole receives funding from the US National Science Foundation.