It’s widely accepted that the primary reason dinosaurs were wiped off the face of the planet was a devastating impact from an asteroid. The Chixulub crater is our best evidence that this theory holds water, and it’s supported by the findings of scientists who study rock and sediment layers deep beneath our feet. But it’s possible, or perhaps even likely, that the asteroid impact wasn’t the only factor in the demise of the dinos, and researchers have long suspected that volcanic activity played a part.
Now, the research team behind a new paper published in Proceedings of the National Academy of Sciences reveals that samples taken from a site called the Deccan Traps in India may finally provide some answers. The Deccan Traps are a huge region of India that was once a massive lava field. The intense volcanic activity that occurred tens of millions of years ago in this location was thought to be a plausible cause of the dinosaur extinction event. This latest batch of data suggests that’s not the case.
We know that in order to wipe out so many species on a global scale, whatever caused the extinction likely affected the atmosphere in a dramatic way. If the volcanism theory was true, the amount of CO2 released by the volcanic activity would have been massive, flooding the atmosphere with the gas and causing global temperatures to rise as a result. Even a change of a few degrees would have been enough to trigger a chain reaction that caused the food chain to collapse.
What the researchers found was that the levels of CO2 released by the Deccan Traps — a process called outgassing — during the centuries leading up to the extinction simply weren’t high enough to have affected global temperatures on such a dramatic level. Put simply, if the ground beneath the volcanism theory was already shaky, it just became even more unsteady.
The team analyzed “frozen” magma samples trapped in crystals that offer an accurate estimate of the amount of CO2 that had the potential to be released during the eruptions in the Deccan Traps. They found that while the Deccan Traps did eventually release enough CO2 to warm the planet by a significant amount, the extinction was already well underway by the time that level of outgassing occurred. This suggests that volcanism wasn’t what triggered the extinction and supports the theory that the asteroid impact was a more likely cause.
“Our lack of insight into the carbon released by magmas during some of Earth’s largest volcanic eruptions has been a critical gap for pinning down the role of volcanic activity in shaping Earth’s past climate and extinction events,” Professor Benjamin Black, principal investigator of the study, said in a statement. “This work brings us closer to understanding the role of magmas in fundamentally shaping our planet’s climate, and specifically helps us test the contributions of volcanism and the asteroid impact in the end-Cretaceous mass extinction.”