Fossil Corals from Galápagos

Why in News?

A landmark paleoclimatological study by researchers from the University of Michigan has analyzed a 1,000-year archive preserved in fossil corals from the Galápagos Islands.

Key Highlights of the Study

• Researchers sampled core records from 13 coral colonies including living structures and ancient fossilized coral boulders in the Galápagos archipelago to reconstruct ocean temperature variations.
• The study revealed that El Niño events have intensified by nearly 36% over the past 40 years compared to pre-industrial baselines (~1850).
• El Niño events over the past 4 decades (including major events in 1982–83 and 1997–98) are roughly 36% stronger than during the pre-industrial era, exceeding any natural variability seen over the last 1,000 years.
• The data demonstrates that the strength of El Niño events changes in direct parallel with rising global surface temperatures.
• Climate model simulations revealed that natural internal climate processes alone could not account for such a massive shift in intensity during the recent 40-year window.

Scientific Context

• Corals as Natural Thermometers- Massive corals grow by 1 to 2 centimetres annually by secreting layers of calcium carbonate (CaCO3).
• The chemical composition of these layers preserves an accurate record of seawater temperature and salinity at the time of growth.
• Galápagos as Ground Zero - The Galápagos Islands are located in the eastern tropical Pacific Ocean, where El Niño's sea surface temperature (SST) anomalies and upwelling disruptions exert their maximum physical impact.
• ENSO Disruption - Under normal conditions, equatorial trade winds push warm surface waters westward toward Australia.
• During El Niño, these trade winds weaken, causing warm water to shift back eastward toward South America, altering global atmospheric circulation and driving extreme weather worldwide.

Reference

Down To Earth | Climate change is strengthening El Niño