Scientists focus on role of volcanoes in extinction of dinosaurs

Earth has experienced five major mass extinction events in the past 500 million years. Massive volcanic eruptions have been identified as the main driver of environmental changes that precipitated at least three of these extinction events. The fifth and most recent event – the late Cretaceous mass extinction – happened 66 million years ago and was responsible for the annihilation of the dinosaurs. Researchers have long questioned whether gas emissions from volcanic eruptions from the Deccan Traps (a huge volcanic province located in India) or the impact of a large asteroid are the most responsible for the climate changes that triggered this event. Now a multi-institutional research team led by scientists from the Graduate Center, CUNY has analyzed the amount and timing of CO₂ degassing (one of the main gases released by Deccan traps) to further determine the role that volcanism played in climate change at the time of mass extinction in the late Cretaceous.

Recent research has identified a global warming event that occurred several hundred thousand years before the end of the Cretaceous extinction. Some scientists have linked the eruption of the Deccan traps to this warming event, but there is debate over whether the lava that erupted could have released enough CO.₂ in the atmosphere to cause it. Adding to this mystery, the volumes of lava that erupted during this period are relatively small compared to the volumes exploded during subsequent stages of the Deccan Traps activity. A major challenge in this debate has been the lack of CO₂ data on Deccan magmas from this time.

“Our team analyzed Deccan Traps CO₂ budgets that coincided with the warming event, and we found that the carbon outgassing of lava volumes alone could not have caused this level of global warming, ”said Andres Hernandez Nava, doctoral student at the Graduate Center, CUNY’s Earth and Environmental Scientific Program and first author of a recently published paper in the Proceedings of the National Academy of Sciences newspaper detailing the new discoveries on this event. “But, when we took into account the outgassing of magmas that froze below the surface rather than erupting, we found that the Deccan traps could have released enough CO.₂ to explain this warming event. “

For their study, the team, which included Hernadez Nava and Professor Benjamin Black of the Graduate Center and City College of New York (CUNY); geochemist Sally Gibson of the University of Cambridge; Virginia Tech geoscientist Robert Bodnar; geologist Paul Renne of the University of California, Berkeley; and geochemist Loÿc Vanderkluysen from Drexel University – used lasers and ion beams to measure the amount of CO₂ inside tiny droplets of frozen magma trapped inside Deccan Traps crystals from the Late Cretaceous period. They also measured the amounts of other elements, such as barium and niobium, which can serve as indicators for the amount of CO₂ the puddles started with. Finally, they modeled the last Cretaceous climate to test the impacts of carbon release from Deccan Traps on surface temperatures.

The team’s findings help fill a significant knowledge gap about how magmas interacted with climate during this crucial period in Earth’s history. Their data show that CO₂ the outgassing of the Deccan Traps magmas may explain a warming of the Earth’s global temperatures of around 3 degrees Celsius during the early stages of Deccan volcanism, but that there was not much warming by the time we reached the mass extinction event, supporting the idea that later Deccan magmas did not release as much CO₂. This new knowledge discourages the theory that volcanic CO₂ was one of the main drivers of the most recent mass extinction.

“Our lack of understanding of the carbon released by magmas during some of Earth’s largest volcanic eruptions has been a critical gap in understanding the role of volcanic activity in shaping Earth’s past climate and extinction events. said Black, the study’s principal investigator and a professor in the Earth and Environmental Sciences program at CUNY Graduate Center and City College of New York. “This work brings us closer to understanding the role of magmas in the fundamental formation of our planet’s climate, and specifically helps us to test the contributions of volcanism and the impact of asteroids in the late Cretaceous mass extinction. . ”