An illustration depicting the onset of the end-Permian mass extinction. Image credit: Dawid Adam Iurino / PaleoFactory, Sapienza University of Rome / Jurikova et al, doi: 10.1038/s41561-020-00646-4.
SciNews has a story about new research that provides insights into the causes of the "Great Dying". The End Permian Mass Extinction was the worst extinctionsin Earth's history. It occurred about 252 million years ago. During it, about 96% of all marine species and over 70% of terrestrial species went extinct. Those percentages are for whole species not individuals... it was truly a catastrophe of epic proportions! Massive volcanic eruptions in what is now Siberia played a central role, but the causal trigger and the feedbacks that led to climate change are not fully understood. Recently, a research team led by Dr Hana Jurikova of the GEOMAR Helmholtz-Zentrum fur Ozeanforschung Kiel published a paper (in the journal Nature Geoscience) that provides a consistent reconstruction of the mechanism that led to this mass extinction event.
Dr. Jurikova and her colleagues studied isotopes of the element boron in the calcareous shells of fossil brachiopods and determined the rate of ocean acidification over the Permian-Triassic boundary.
“These are clam-like organisms that have existed on Earth for more than 500 million years,” Dr. Jurikova said.
“We were able to use well-preserved brachiopod fossils from the Southern Alps for our analyses.”
“These shells were deposited at the bottom of the shallow shelf seas of the Tethys Ocean 252 million years ago and recorded the environmental conditions shortly before and at the beginning of extinction.”
Because the ocean pH and atmospheric carbon dioxide are closely coupled, the researchers were able to reconstruct changes in atmospheric carbon dioxide at the onset of the extinction from boron and carbon isotopes.
They then used an innovative geochemical model to study the impact of the carbon dioxide injection on the environment.
“With this technique, we can not only reconstruct the evolution of the atmospheric carbon dioxide concentrations, but also clearly trace it back to volcanic activity,” said co-author Dr. Marcus Gutjahr, a researcher at the GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel.
H. Jurikova et al. Permian-Triassic mass extinction pulses driven by major marine carbon cycle perturbations. Nat. Geosci, published online October 19, 2020; doi: 10.1038/s41561-020-00646-4