Earth Entered a 56-Million-Year Ice Age, But Something Unexpected Kept Happening
Indian Defence Review • • science
Key Points:
- Around 717 million years ago, Earth experienced the Sturtian glaciation, a prolonged global freeze lasting about 56 million years, traditionally difficult for climate models to explain as a continuous event.
- A new study from Harvard University proposes that rather than a single continuous freeze, the Sturtian involved repeated cycles of glaciation and thaw driven by interactions between atmospheric CO₂ levels and the chemical weathering of volcanic basalt.
- The Franklin Large Igneous Province's basalt weathering initially reduced CO₂ to trigger glaciation, but as ice coverage limited weathering, volcanic CO₂ emissions accumulated, warming the planet and causing ice retreat, thus creating a feedback loop sustaining climate oscillations.
- This freeze-thaw cycle model explains geological evidence of alternating glacial and open-water conditions and suggests intermittent warm periods allowed oxygen-dependent microorganisms to survive through the Sturtian.
- The findings imply that similar carbon-cycle-driven climate oscillations could occur on other rocky planets, meaning a frozen surface does not necessarily indicate a permanently lifeless world.