Movies, textbooks, and conventional wisdom have long treated the The extinction of the dinosaurs at the end of the Cretaceous Period is one of several Mass Extinctions on Earth, and evidence suggests that looking at what they all have in common may offer more conclusive insights into their causes.
The extinction of the dinosaurs 66 million years ago is the most studied of the five Mass Extinctions that have occurred over the past 500 million years. The event marks the end of the Cretaceous period. There is little doubt that the impact of a massive asteroid, dubbed Chicxulub, contributed to the extinction of 75 percent of plant and animal species living on Earth, giving mammals and birds the opportunity to flourish. The asteroid’s impact triggered a cascade of devastation, including powerful earthquakes, tsunamis, and wildfires, creating conditions that were survived by few.
Despite the decimation sparked by the asteroid’s impact, however, recent research led by experts at Dartmouth and published in eruption of Hunga Tonga–Hunga Haʻapai pale in comparison. Mount St. Helens, which famously erupted in 1980, boasted less than one cubic meter of magma. By dating the resulting lava fields, researchers were able to determine that mega eruptions usually occur alongside Mass Extinctions.
The Sixth Extinction Could Be Underway
Photo by Danny Grizzle on Unsplash
In research indicates that volcanic eruptions proliferating across the Indian subcontinent at the time of the dinosaur die-off would have created environmental conditions that were, for most of Earth’s species, impossible to survive.
For years, scientists have warned that Earth is in crisis, and perhaps even in the midst of a sixth Mass Extinction event as thousands of species face plummeting populations. Whether the Mass Extinctions of the past can help prevent dire consequences in the present remains to be seen. The creation of a large igneous province releases an astronomical quantity of carbon dioxide into the atmosphere, and similar carbon dioxide emissions from human activity are creating an eerily parallel effect. Brenhin Keller, an assistant professor of earth sciences at Dartmouth and one of the study’s co-authors, warns that while modern carbon dioxide emissions are not on par with those emitted by a large igneous province, “We’re emitting it very fast, which is reason to be concerned.”
Even without an asteroid impact or a supervolcano, the ongoing fossil-fuel driven climate disaster raises the specter of an irreversible and devastating die-off. Species-level destruction need not be as dramatic as a meteor blocking out the sun – it can be as gradual as the flooding of an entire continent with lava over the course of a million years.
It's incredibly challenging to establish causality, especially for events that took place millions of years in the past. While the study cannot conclusively claim a specific volcanic eruption caused a Mass Extinction, this new evidence makes it difficult to dismiss the idea that volcanic activity played a role in the extinction of non-avian dinosaurs. Even without the impact of Chicxulub, it seems likely that the dinosaurs were not long for this world. It's a revelation that suggests that once DART establishes that humans can deflect asteroids away from Earth, it might be wise to divert some additional energy to climate change and rising levels of carbon dioxide.
Source: PNAS, Dartmouth College