16 Year Winter Finished The Dinosaurs

Most people would be able to say that it was an impact by an enormous meteor that did for the dinosaurs 66 million years ago. I have written previously about the less commonly known vulcanism of the Deccan Traps which also played a likely sizeable role. Together, these two were responsible for wiping out 75% of all the species on earth as the cretaceous period moved into the paleogene. No animal weighing more than 25kg survived.

Working out the relative contributions of the meteor and the vulcanism is an ongoing scientific debate and one I enjoy following.

In a new analysis published in Geophysical Research Letters, researchers from the US and UK have tried to quantify just how bad the Chicxulub impact was. This isn’t the first time this kind of analysis has been done, but this new attempt claims to be more accurate as they take into account more factors like the angle of impact of the crater.

The result is 325 gigatons of sulphur and 425 gigatons of carbon dioxide hurled into the atmosphere at more than a kilometre per second. This would have blotted out the sun’s light and heat leading to a sub-zero winter that lasted for between 3 and 16 years. Combine that with hurricane force winds, long term major global warming due to the CO2, ocean acidification and global firestorms and you’ve got, well, a pretty bad day.

It’s no wonder those poor non-avian dinosaurs failed to make the cut. Pesky little critters, like all mammals were back then, could have survived on what scraps remained during the years long winter; but there just wasn’t enough for the leviathan dinosaurs to get by on.

The authors don’t address whether or not this makes the Chicxulub impact more or less significant relative to the Deccan vulcanism, but combined with 10 million years of massive eruptions it’s a wonder that anything survived at all.


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