Galápagos corals show El Niño events are more extreme now than in past 1, 000 years – here’s how my team made the discovery
A NOAA scientist takes a coral sample in the Galapagos Islands. The process does not injure the colony, which grows back.
El Niño is a climate pattern that begins in the eastern tropical Pacific Ocean, near the Galápagos Islands. It involves a shift in trade winds that warms ocean surface temperatures, altering atmospheric circulation worldwide. This leads to changes in weather patterns, including floods, droughts, and tropical storms across the globe. For example, the 1982-83 and 1997-98 El Niño events caused extreme weather globally, resulting in climate disasters and economic losses estimated at up to $4 trillion. These events also disrupt marine ecosystems, such as the Galápagos Islands, where warm waters block the upwelling of cool, nutrient-rich water, harming marine life and local communities dependent on fishing.
Corals act as natural record-keepers of ocean temperatures over centuries. As they grow, they form annual layers in their skeletons, similar to tree rings. By analyzing the chemical composition of these layers, scientists can reconstruct past ocean temperatures. In this study, researchers examined both living and fossil corals from the Galápagos Islands. They measured two chemical ratios—oxygen isotopes and strontium to calcium—to track temperature changes. This method revealed seasonal cycles and extreme temperature events, providing a history of El Niño and La Niña patterns over the past millennium.
The Galápagos Islands are located in a region where El Niño events cause significant temperature swings. Scientists drilled core samples from living corals and collected fossil corals up to 4,500 years old. These samples showed clear evidence of the devastating 1982-83 El Niño event, including 'death horizons'—layers of calcified material from other organisms that interrupted coral growth. By analyzing thousands of samples, the team reconstructed a detailed history of El Niño and La Niña events, revealing that recent El Niño events have been stronger than any in the past 1,000 years.
The study found that El Niño events over the past 40 years have been stronger than at any other time in the past millennium, coinciding with human-caused global warming. The data aligns with thermometer measurements from the past century but extends much further back in time. The intensification of El Niño appears greater than what most climate models predict from natural causes alone, suggesting a connection to global warming. This finding helps scientists identify which climate models most accurately reflect real-world observations.
Stronger El Niño events mean more intense and damaging climate extremes worldwide. Scientists can forecast these events up to a year in advance using data from satellites, buoys, and climate models. Continuous monitoring and improvements in forecasting are critical as global warming accelerates. For example, the National Oceanic and Atmospheric Administration (NOAA) provides El Niño forecasts and updates. Better predictions can help communities prepare for and mitigate the impacts of these extreme climate events.
