Overview
- The study published July 6 in PNAS reports that warm, oxygen-poor seas were the proximate kill mechanism for marine species during the Permian–Triassic mass extinction.
- Researchers tested the idea experimentally by measuring metabolic tolerance to higher temperatures and lower oxygen in living relatives of pre‑ and post‑extinction animal groups.
- Species that died out showed much lower tolerance for warm, hypoxic water while survivors had physiologies that allowed them to cope, which helps explain the shift from brachiopod‑dominated to bivalve‑dominated faunas.
- The authors tie the ocean stress to massive volcanic emissions from the Siberian Traps that raised global temperatures and reduced dissolved oxygen in seawater.
- The paper warns that although ancient warming was larger and slower, modern human-driven warming is faster and could create similar low‑oxygen ocean conditions unless emissions are cut and mitigation actions are taken.