What killed the dinosaurs? Was it just the fall of a meteorite, as is commonly believed?
A new study published in the journal Science Advances suggests that the meteorite falling to Earth was only part of the story, and that climate change caused by massive volcanic eruptions may have been what ultimately paved the way for the extinction of the dinosaurs, which challenges the traditional narrative that… That the meteorite alone dealt the final blow to the ancient giants.
The international team led by scientists from McGill University published a press release about the study; Volcanic eruptions in the Deccan Terraces, a vast, rugged plateau in western India formed from molten lava. These explosions, which left one million cubic kilometers of rock behind, may have played a major role in cooling the global climate about 65 million years ago.
Researchers from all over the world participated in this work, from hammering and breaking up rocks on the Deccan terraces to analyzing samples in England and Sweden.
In the laboratory, scientists estimated the amount of sulfur and fluorine that was injected into the atmosphere through massive volcanic eruptions during the 200,000 years before the extinction of the dinosaurs. Remarkably, they found that the release of sulfur could lead to a global drop in temperatures around the world, a phenomenon known as volcanic winter.
“Our research shows that climate conditions were almost certainly unstable, with frequent volcanic winters that could have lasted for decades, before the extinction of the dinosaurs,” says Don Baker, a professor in the Department of Earth and Planetary Sciences at McGill University and a co-author of the study. “This would make life difficult for all plants and animals and pave the way for a dinosaur extinction event.”
He adds: “Our work helps explain the major extinction event that led to the emergence of mammals and the evolution of our species.”
Uncovering clues inside ancient rock samples has been no easy feat. A new technique developed at McGill University has helped decipher volcanic history. Estimating sulfur and fluorine emissions (a complex mixture of chemistry and experiments) is a bit like cooking pasta.
Baker explains: “Imagine making pasta at home. You boil the water, you add salt and then the pasta. Some of the salt from the water goes into the pasta, but not much of it.” Likewise some elements become trapped in minerals when they cool after a volcanic eruption.
Just as you can calculate the salt concentration in the water in which pasta is cooked by analyzing the salt in the pasta itself, the new technique has allowed scientists to measure sulfur and fluorine in rock samples.
With this information, scientists were able to calculate the amount of these gases emitted during explosions, and their findings represent a step forward in piecing together the Earth's ancient secrets and paving the way for a more informed approach to our changing climate.