Organic Carbon Erosion Amplified Jurassic Warming
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- Dr. Madeleine Stow of the University of Oxford led a Nature Communications study with UK and French colleagues testing how rock weathering (which removes CO2) and organic carbon erosion (which emits CO2) competed during the Toarcian Ocean Anoxic Event 183 million years ago.
- The researchers found that eroding organic carbon amplified warming during the Toarcian event, suggesting the same process may apply to modern climate change — though the team cautioned the past-as-prologue link remains uncertain.
- The Toarcian warming event was triggered by massive volcanic eruptions across what is now South Africa and Antarctica (then joined together), producing 6° to 7°C of warming, reshuffling plant and dinosaur species, and causing mass extinction of corals and other marine life.
- University of Oxford professor Bob Hilton, coauthor and principal investigator, said the event had been well-studied previously: "We understand its drivers, we understand how it caused mass extinctions, and it's driven by this Large Igneous Province release."
- Conventional understanding since the early 1980s held that rock weathering slowly removes CO2 from the atmosphere; recent studies then revealed erosion also emits CO2 by oxidizing organic carbon in sediments — a tension the new study aimed to resolve.
- The Toarcian event is one of about a dozen past climate episodes triggered by Large Igneous Provinces, several linked to mass extinctions including the end-Permian Great Dying caused by the Siberian Traps.
Why it matters: The study reframes rock weathering from a straightforward climate-cooling CO2 sink into a process with a warming side: organic carbon eroded from sediments released CO2 that amplified the Toarcian event's 6–7°C spike. That complicates the simple 'weathering regulates climate' model scientists have relied on since the 1980s, though the Oxford team itself flags the modern analogy as uncertain.
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