New Research Uncovers Cause of Earth’s Largest Mass Extinction

A new study, led by a Montclair State University researcher and published in Proceedings of the National Academy of Sciences of the United States of America, holds the key to the largest mass extinction in history – and shows why we may be headed for a similar, significant event.

Led by Assistant Professor of Earth and Environmental Studies Ying Cui, the research, titled “Massive and rapid predominantly volcanic CO2 emission during the end-Permian mass extinction,” shows the event – in which Earth lost 80% of marine and 70% of terrestrial species – was caused by rapidly rising carbon dioxide levels due to volcanic eruptions of the Siberian Traps in Russia.

The results also show that CO2 emissions that caused the end-Permian Extinction were roughly half of the emissions currently being produced on the planet – potentially a sign of things to come if measures are not taken to reduce carbon dioxide-producing activities worldwide.

“This discovery disproves the view that the release of methane was responsible for the largest extinction of all time,” says Cui. “The massive amount of CO2, adding up to 36,000 gigatons of carbon, released in a short period of time provides a lesson for the extent of future biodiversity loss if the increase in CO2 emissions continues unabated. Knowing the trigger of this event will help understand processes that may forestall extinction in the future.”

A Rare Find Leads to Discovery

The research team examined two exceptionally well-preserved drill cores (long cylindrical samples extracted from rock) from the Finnmark Platform, a region north of Norway, and analyzed the ratio of carbon isotopes with differing numbers of protons and neutrons preserved in organic compounds for hundreds of millions of years. These compounds contain long-chain (carbon number greater than 25) and short-chain (carbon number smaller than 19) normal alkanes, which serve as “biomarkers” for land plants and marine algae. Their carbon isotopes, in turn, reflect past carbon cycle changes happening on land and in the ocean.

The rare ability to examine these specimens provided the team with the chance to be more precise in their calculations and Earth system modeling. Additionally, the team achieved increased accuracy by including recent studies of seawater temperature based on oxygen isotopes and seawater acidity (pH) based on boron isotopes.

The results show carbon dioxide emissions that would have fundamentally changed the marine ecosystem structure, driving organisms into extinction.

“The measurements of compound-specific carbon isotopes for samples this old are rare and difficult to make,” says Cui. “The carbon isotopes of land plants have a larger response than marine algae to CO2 emissions, suggesting the surface ocean was out of equilibrium with the atmosphere, and only a rapid CO2 emission can explain that.”

Implications for Present Day

The study shows the unprecedented impact high carbon dioxide emissions can have on the environment – and what could happen in the future if significant changes are not made to reduce emissions around the world.

“Human activities cause pollution, deforestation and climate change, which have already led to decreased biodiversity,” says Cui. “Wildfires, hurricanes and heat waves are becoming more frequent, and loss of habitat and extinction are already underway. The results of this study – and how they were achieved – show that the “deadly trio” of deoxygenation, warming and acidification have already pushed the Earth’s system beyond tipping points once before, and could do so again if emissions continue at their current rate.”

To learn more about the Earth and Environmental Studies program at Montclair State University, visit montclair.edu/earth-and-environmental-studies/.