Overview
- Researchers published a Stanford-led paper in PNAS on July 6 that ties repeated volcanic releases of CO2 and methane to ocean warming and deoxygenation that drove the Permian–Triassic mass extinction.
- The team collected live brachiopods from the San Juan Islands and used controlled respirometry tests to measure how oxygen consumption changed with rising water temperature.
- Results show brachiopods tolerate low oxygen but their metabolic demand climbs steeply as water warms, making them vulnerable when oxygen levels fall.
- By contrast, bivalves, many fishes and echinoderms have more efficient oxygen-uptake physiology, which the authors say helped those groups survive and later dominate modern seafloors.
- The authors warn the ancient sequence—greenhouse-gas injection, ocean warming, loss of dissolved oxygen, and selective extinctions—offers a cautionary parallel to present CO2-driven warming and the projected 21st-century rise in ocean temperatures.