Toxic gas released by ancient microbes may have worsened Earth’s largest mass extinction

Dominik Hülse, an Earth system modeler based at University of California Riverside, worked on a November 2021 study that explored how ancient microbes may have prolonged the Permian extinction by producing a toxic gas. Here, Hülse poses with a finger to his nose to highlight the toxic “rotten egg” scent of hydrogen sulfide. (Image credit: Dominik Hülse/UCR)

Algal blooms in coastal waters and toxic chemical exposures at oil facilities are modern problems. Their root causes, however, have a lot in common with the largest mass extinction in Earth’s history 250 million years ago. 

298.9 million years ago the Permian period, the last period of the Paleozoic era, began. This period of time had plenty of aquatic animals and archaic land creatures like dimetrodons. Scientists think that towards the end of the Permian period, volcanoes in Siberia went into overdrive and dramatically warmed the planet, triggering the Permian extinction, the most devastating decimation of life on Earth when about 95% of all marine species, as well as about 70% of terrestrial species, disappeared.