The Dark and Extreme Cold Killed Off the Dinosaurs

Computer models show that global temperature drops after an asteroid struck 66 million years ago lasted longer than previously thought.


The chill that enveloped Earth 66 million years ago, after an asteroid struck and ushered the dinosaur era to a close, lasted longer, with greater consequences, than previously thought.

That's according to new research by scientists with the Potsdam Institute for Climate Impact Research (PKI), who argue, in a new study published in the journal Geophysical Research Letters, that droplets of sulfuric acid forming high in the air after the impact brought about a long-lasting plunge in temperatures, playing a key role in the demise of the dinosaurs at the end of the Cretaceous.

"The long-term cooling caused by the sulfate aerosols was much more important for the mass extinction than the dust that stays in the atmosphere for only a relatively short time," said study lead Georg Feulner, in a statement. "It was also more important than local events like the extreme heat close to the impact, wildfires or tsunamis."

Existing studies, the PKI team wrote, "focused on the effect of dust or used one-dimensional, non-coupled atmosphere models." Feulner and his team instead used new computer models that coupled atmosphere, ocean and sea ice data in order to run their simulations.

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The resulting post-impact computer models painted a dire picture for dinosaurs accustomed to a lush environment: a global mean surface air temperature drop of at least 26 degrees C.; three to 16 years of sub-freezing temperatures; and a climate recovery time of more than 30 years.

Computer modeling showed an enduring chill passing over the planet after the asteroid strike. Credit: PKI

(The PKI team has created a time-lapse animation of the cooling that can be viewed here.)

All was chaos in the oceans, too, the models showed. As surface waters cooled, they grew heavier and denser, sinking. Meanwhile warmer waters farther below rose, bringing with them nutrients that created huge algae blooms. The blooms could have created toxic substances that impacted life along the coastlines, the scientists suggested.

"The big chill following the impact of the asteroid that formed the Chicxulub crater in Mexico is a turning point in Earth history," said the study's author Julia Brugger. "We can now contribute new insights for understanding the much-debated ultimate cause for the demise of the dinosaurs at the end of the Cretaceous era."

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