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Similar global warming conditions associated with two mass extinctions

Media release

Researchers have discovered two of Earth’s ancient mass extinctions wiped out life on the planet in a similar way to one another, providing a solid grounding on how mass extinctions happen.

St Audrey's Bay, location of fossil find
St Audrie's Bay, United Kingdom. Rock samples were collected from this location to determine the oceanic and atmospheric conditions that caused the end-Triassic extinction 200 million years ago (Credit: L. Felipe Opazo, Plymouth University)

The Curtin University-led research, recently published in Geology, was able to demonstrate the cascade 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 250 million years ago.

The research suggests perhaps all global warming-related mass extinctions show similar patterns of change.

From rock samples collected by colleagues in Plymouth University, lead scientists Professor Kliti Grice, Director of the WA 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).

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 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.”

Dr Jaraula said the research team looked at stable carbon isotopes of molecular fossils of plant waxes, algae and chlorobi before, during and after the extinction period.

Professor Richard Twitchett of Plymouth University said the next step was to compare the results to changes in the fossil record of marine animals, to help understand how future marine extinctions are likely to occur.

“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,” Professor Michael Böttcher, of the Leibniz Institute for Baltic Sea Research, Germany, said.

Professor Grice and her research colleagues previously determined the conditions of the largest extinction occurring at the end of the Permian, 250 million years ago in a report published in Science in 2005.

The recently published research in Geology was carried out in conjunction with Plymouth University and 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.

Read the paper, Elevated pCO2 leading to Late Triassic extinction, persistent photic zone euxinia, and rising sea levels.

Media Contact:

Professor Kliti Grice, Department of Chemistry, Curtin University
Tel: 08 9266 2474; Email: K.Grice@curtin.edu.au

Dr Caroline Jaraula, Department of Chemistry, Curtin University
Tel: 08 9266 3819; Email: C.Jaraula@curtin.edu.au

Megan Meates, Public Relations, Curtin University
Tel: 08 9266 4241; Mobile: 0401 103 755; Email: megan.meates@curtin.edu.au

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