113-Million-Year-Old Fossils Show Volcanic CO2 Drove Ocean Acidification and Plankton Extinction

New research from Northwestern University used chemical signals in microscopic fossil shells to link a major plankton extinction 113 million years ago to volcanic carbon dioxide emissions. The eruptions from the Kerguelen Plateau in the southern Indian Ocean released massive amounts of CO2, which dissolved into the ocean and acidified surface waters, killing off many shell-building plankton species. The study highlights how rapid carbon release can destabilize marine ecosystems. While the timescale differs from modern emissions, the mechanism is a direct analog for current ocean acidification. Understanding these ancient events helps refine models of how CO2 affects ocean chemistry and marine life, which matters for climate policy and carbon management decisions today.