[DLS] Justin Penn (Princeton University)

“Extinctions from Hypoxia in a Warming Ocean: Ancient Lessons for the Future”

Paleoclimate intervals of rapid warming provide potential analogs for the future but yield different prognoses for marine biodiversity. In this talk, I will explore why species losses during the Paleocene-Eocene Thermal Maximum (PETM) were muted compared to the Big Five mass extinctions, except in the deep-sea, using ocean simulations that capture reconstructed temperature and O₂ changes, along with a trait-based model of aerobic habitat that previously explained patterns of Earth’s largest extinction, across the Permian/Triassic (P/Tr) boundary. During the PETM, simulated habitat loss from warming leads to modest extinctions in the upper ocean, consistent with the animal fossil record. However, the additional physiological stress from ocean deoxygenation increases extinction intensity in the abyss, reproducing trends observed in foraminifera. A mass extinction of animals across the PETM would have required a larger temperature rise, comparable to the P/Tr transition, highlighting the role of warming magnitude in ecosystem collapse. Unless future greenhouse gas emissions are limited, this mechanism risks depleting marine biodiversity accumulated over the past ~50 million years of evolutionary history.

EAPS Department Lecture Series
Weekly talks aimed to bring together the entire EAPS community, given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. Runs concurrently with class 12.S501.

Contact: eapsinfo@mit.edu