A discovery of a link between two of Earth’s ancient mass extinctions that had wiped out life on earth in a similar way to one another provides solid grounding on how mass extinctions happen that were both triggered through rises in carbon dioxide (CO2) levels.
The Curtin University-led research, was able to demonstrate the flow of events during the fourth largest extinction, at the end of the Triassic period 200 million years ago, were remarkably similar to those of the largest extinction that occurred at the end of the Permian period 250 million years ago.
T
he Permian mass extinction has been nicknamed The Great Dying, since a staggering 96 per cent of species died out. All life on Earth today is descended from the four per cent of species that survived.
The research suggests perhaps all global warming-related mass extinctions show similar patterns of change.
Professor Kliti Grice, director of the West Australian Organic and Isotope Geochemistry Centre (WA-OIGC) program and Dr Caroline Jaraula and Dr Pierre Le Metayer, Research Fellows of the WA-OIGC program from Curtin, discovered and examined molecular fossils of land plants, algae and green sulfur bacteria (known as Chlorobi) from these time periods.
Alongside their international research team, they were able to determine the oceanic and atmospheric conditions that caused the end-Triassic extinction 200 million years ago.
“Back then, the world’s continents were being pulled apart to create what is now the Atlantic Ocean.
“This event was accompanied by frequent, massive volcanic eruptions that injected great quantities of CO2 into the atmosphere; estimated at four times higher than today’s levels based on plant physiology,” Professor Grice said.
“The high CO2 levels triggered global warming; leading to a cascade of atmospheric and oceanic changes that were very similar to those that we found had caused the largest mass extinction which happened 50 million years prior to this one.
“Of the five mass extinctions to have ever occurred in the past 600 million years, four were associated with global warming.
“Our research suggests if two of these had similar processes operating, perhaps all other global warming-related extinctions do too, helping us understand more about Earth’s history.”
The course of events prior to, during, and after the extinction is remarkably similar to those reported for the Late Permian extinction with the link found in the stable carbon isotopes of molecular fossils of plant waxes, algae and Chlorobi, Dr Jaraula said.
The next to step is to compare the results to changes in the fossil records of marine animals, in order to grasp how future marine extinctions are likely to occur, Professor Twitchett of Plymouth University said.
“Our study has provided a glimpse of how extinctions happen and their rates of change.
“While ocean circulation and aspects of the carbon cycle will always be different, the general patterns of change can still be compared,” said Professor Michael Böttcher, of the Leibniz Institute for Baltic Sea Research, Germany.
The research has been funded by the Australian Research Council under a QEII Discovery Fellowship awarded to Professor Grice and Professor Twitchett.
Professor Grice has also recently been awarded a Discovery Outstanding Research Award to continue this research and investigate the recovery of the largest extinction events and their association with oil and gas resources on a global scale.
