Worst mass extinction event in Earth’s history was caused by global warming analogous to current climate crisis
By Mike Gaworecki
3 January 2019
(Mongabay) – New research by scientists at the United States’ University of Washington and Stanford University suggests that the most destructive mass extinction event in Earth’s ancient history was caused by global warming that left marine life unable to breathe.
The Permian period, the last period of the Paleozoic Era, ended about 250 million years ago with the largest recorded mass extinction in Earth’s history. Before the dinosaurs emerged during the Triassic period somewhere around 243 and 233 million years ago, a series of massive volcanic eruptions is believed to have triggered global climate change that ultimately led to the Permian extinction, which wiped out 96 percent of marine species in an event known as the “Great Dying.”
According to Justin Penn, a doctoral student at the University of Washington (UW), the Permian extinction can help us understand the impacts of climate change in our own current era. He’s the lead author of a study published in Science last month that builds off of previous research by Curtis Deutsch, a professor of oceanography at UW.
“In 2015, Curtis published a paper demonstrating that temperature and oxygen act as invisible barriers to habitat for animals in the modern ocean,” Penn told Mongabay. “We wanted to know whether this framework could be used to understand the link between ocean warming, oxygen loss, and marine ecosystems. The end-Permian mass extinction served as the perfect case study because there is clear evidence for ocean warming and oxygen loss during that time period, and the fossils recorded the response of marine biodiversity.”
Penn led a team of researchers that combined models of ocean conditions and animal metabolism with paleoceanographic records to show that the Permian mass extinction was caused by rising ocean temperatures, which in turn forced the metabolism of marine animals to speed up. Increased metabolism meant increased need for oxygen, but the warmer waters could not hold enough oxygen to meet those needs, and ocean life was left gasping for breath. [more]
ABSTRACT: Rapid climate change at the end of the Permian Period (~252 million years ago) is the hypothesized trigger for the largest mass extinction in Earth’s history. We present model simulations of the Permian/Triassic climate transition that reproduce the ocean warming and oxygen (O2) loss indicated by the geologic record. The effect of these changes on animal survival is evaluated using the Metabolic Index (Φ), a measure of scope for aerobic activity governed by organismal traits sampled in diverse modern species. Modeled loss of aerobic habitat predicts lower extinction intensity in the tropics, a pattern confirmed with a spatially explicit analysis of the marine fossil record. The combined physiological stresses of ocean warming and O2 loss can account for more than half the magnitude of the “Great Dying.”
