Aerobic Marine Habitat Loss During the Late Permian Extinction
Abstract
Rapid climate change at the end of the Permian is thought to have triggered the most severe mass extinction in Earth's history, but the precise mechanism of biodiversity loss is unknown. Geological evidence points to lethally hot equatorial temperatures and an expansion of anoxic ocean waters as likely culprits. However, previous climate model simulations of the warm Early Triassic exhibit weak tropical warming, and anoxic conditions require a massive and unconstrained increase in the ocean nutrient reservoir. Reconciling model predictions with the geologic record remains a key challenge to identifying the kill-mechanism, which must also take into account the role of animal physiology. Here we apply a recently developed index for the metabolic scope of marine animals to the first global climate simulations of the Permian-Triassic transition to quantify the effects of ocean warming and oxygen (O2) depletion on aerobic habitat availability. Forcing with extreme CO2 concentrations warms the surface ocean by over 10oC, consistent with paleoproxies for upper ocean temperature change. Warming depletes global O2, with greatest losses occuring in tropical deep waters as a result of their reduced ventilation. Together warming and deoxygenation would have constricted the occurrence of marine habitat by 80% globally, by decreasing the metabolic index of the Permian ocean. These changes are most pronounced in the tropics where the fossil record suggests recovery was severely inhibited. Fossil deposits also record changes in animal body size across the extinction. We find that adaptation via body size reductions can compensate for increasing hypoxia at high latitudes, and even prevent extinction there, but cannot maintain the habitability of the tropics.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP31A2267P
- Keywords:
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- 0330 Geochemical cycles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0343 Planetary atmospheres;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHYDE: 5225 Early environment of Earth;
- PLANETARY SCIENCES: ASTROBIOLOGY