Cretaceous-Paleogene Extinction is Caused by Asteroids, Not Volcanic Activity

Tuesday, January 21, 2020

Cretaceous-tertiary Extinction Event by Richard Bizley

The extinction of the dinosaur is maybe one of the most exciting topics in paleontology wherein scientists offer various possible explanations as to why these apex predators disappeared. Two of the most popular theories on dinosaur extinction was one, an asteroid hit the Earth and two, volcanic activity. However, in a recent study conducted by researchers from Yale University, it is shown that volcanic activity did not play a direct role in the mass extinction of these apex predators. However, the asteroid did.

According to Pincelli Hull, an assistant professor of geology and geophysics and her colleagues at Yale University, the environmental impacts brought by the massive volcanic eruptions that have transpired in the Deccan Traps region happened before the Cretaceous-Paleogene extinction, also known as K-Pg, 66 million years ago, hence, not the primary reason (or even contributed) to the extinction of the dinosaurs. Hull explains that volcanic activity may contribute to mass extinctions because they release a lot of gases including sulfur dioxide and carbon dioxide. These gases alter the climate and may acidify the atmosphere. But the recent work of Hull and her colleagues, which is published in Science, focused on the timing of lava eruption more than the release of the gases.

To be able to pinpoint the timing of the emission of volcanic gas, the researchers compared the global temperature changes and the carbon isotopes from marine fossils to the models of the climatic effects of carbon dioxide. The researchers figured out that most of the gases were released well before the asteroid impact which strengthens their claim of the asteroid being the main reason for the extinction of the creatures of this period. Former Yale researcher (and compiler of the temperature records which they used for analysis) Michael Henehan said that volcanic activity in the late Cretaceous caused a gradual global warming event but only for about two degrees. It is not enough to cause a mass extinction. "A number of species moved toward the North and South poles and these species eventually moved back before the asteroid impact." He said. Hull adds that a lot of scientists speculated that volcanic activities mattered greatly during the Cretaceous-Paleogene extinction. "And we're saying 'no they didn't.'" She said.

It is also important to note that recent studies on the Deccan Traps located in modern-day India show evidence pointing to massive eruptions happening in the immediate aftermath of the Cretaceous-Paleogene extinction. Understandably, these results puzzled scientists since there is no warming event to match those massive eruptions. Luckily, the recent study done by Hull and her colleagues provided an answer to this mystery. According to the study's modeler and postdoctoral associate Donald Penman, since the Cretaceous-Paleogene extinction is a mass extinction, this already altered the global carbon cycle. The results of the study show that the changes allow the ocean to absorb enormous amounts of carbon dioxide for a very long time and this my have hidden the warming effects of the volcanic activities in the aftermath of the extinction.