Microscopic fossils reveal volcanic CO2 triggered massive plankton crash 113 million years ago
Researchers used calcium isotope data from tiny foraminifera shells to link a massive volcanic eruption on the Kerguelen Plateau to an ocean-acidification event that caused a major extinction of surface-dwelling plankton 113 million years ago.
A study led by Northwestern University scientists analyzed hundreds of microscopic foraminifera collected from the Falkland Plateau to investigate an Early Cretaceous extinction event. By measuring calcium isotope ratios in pristine shell material, they detected a pronounced increase coinciding with the disappearance of many planktonic species around 113 million years ago. The researchers attribute this pattern to massive eruptions of the Kerguelen Plateau, which released enough carbon dioxide to lower surface-water pH and reduce carbonate ion availability.
The resulting ocean acidification hampered shell building, especially in surface-dwelling foraminifera, while deeper-living benthic forms experienced only modest changes. This isotopic signal offers a robust marker for linking volcanic CO2 emissions to marine extinctions, reinforcing a pattern seen in other ancient climate upheavals. The work underscores how past greenhouse episodes can inform expectations for modern ocean acidification driven by human CO2 emissions.
Why it matters
It shows how large volcanic CO2 releases can acidify oceans and trigger massive plankton losses, a warning for today’s rising CO2 levels.
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