Volcanoes didn’t really affect dinosaur extinction, study says

Volcanoes may have had less of an impact on the extinction of the dinosaurs than previously thought, according to a new study out of the University of Leeds.

Before, asteroid impacts and long-term volcanic reactions were both considered major players in early mass extinction events, propelling gas and dust into the atmosphere that altered the climate for years. But the repercussions of volcanic sulfur dioxide emissions wasn’t entirely sure—until now.

The study, which is published in Nature Geoscience, provides the first quantitative estimate of the impact these gases had on the Earth’s climate.

“At the time when the dinosaurs reigned, numerous long-lasting eruptions took place over the course of about a million years,” explained lead author Dr. Anja Schmidt, from the university’s School of Earth and Environment, in a statement. “These eruptions, called ‘continental flood basalts’ were not like volcanic eruptions we often see today, with lava gushing from the ground like a curtain of fire.

“Each eruption is likely to have lasted years, even decades, and eruptions were separated by periods without volcanic activity. The lava produced by an eruption of average intensity would have filled 150 Olympic-size swimming pools per minute.”

This certainly seems like something that would bring about the dinos’ demise—but the study found otherwise. Instead, the computer simulation created by the researchers found that the effects were far less devastating.

Volcanoes not very impactful

After inputting information on the duration and intensity of these continental flood basalt eruptions, the simulation was able to estimate the climactic and environmental changes that occurred thanks to the sulfur dioxide emissions. Researchers discovered that these eruptions did, in fact, make the Earth cooler, by as much as 40 degrees Fahrenheit.

However, assuming that climate feedbacks were similar to what we see today, these temperature changes only lasted for about 50 years before returning to normal—making the impact much less enduring than expected.

“Perhaps most intriguingly, we found that the effects of acid rain on vegetation were rather selective. Vegetation in some but not all parts of the world would have died off, whereas in other areas the effects would have been negligible,” said Schmidt.

Which means that, in light of this study, previous theories concerning mass extinctions and volcanoes will have to be re-examined for their accuracy.

“We now need to better understand how long both the individual eruptions and the periods without volcanic activity lasted,” Schmidt added.

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Feature Image: Michelle Parks (University of Iceland)