We know that a monstrous asteroid impact killed the (non-avian) dinosaurs at the end of the Cretaceous period. Sixty-six million years ago, a 10-kilometer-wide space rock crashed into Earth just off the coast of present-day Yucatan, destroying a 150-kilometer-wide crater and unleashing a chain of catastrophic weather events that destroyed the 75% of all species on the planet.
However, in recent years, evidence has accumulated of another exaggerated disaster at the same time: a major volcanic eruption event in India, creating what is now called the Deccan traps. This was not like a single volcano blowing its top; this was a series of huge eruptions that lasted hundreds of thousands of years. At the time they declined, 500,000 square kilometers above the area were buried 2 kilometers deep with igneous rocks.
There is now pretty good evidence that the Deccan eruptions continued for a time. before the impact of the asteroid, and soon after the volume of the eruption increased substantially, probably due to seismic waves from the impact of the asteroid that opens the valves underground, so to speak.
Due to the timing, some paleontologists suggested that the two crises worked together, giving the dinosaurs a double whammy from which they could not recover.
However, a firm conclusion has been difficult to draw. And now a new article has been published arguing against the idea of the co-dinosaur-end of the world. Scientists claim the impact did all the dirty work, and the Deccan traps, while apocalyptic in scale, may have only helped a little. Not only that, but they also suggest that, strangely, the eruptions may have helped Earth’s life. recover of impact!
They used models of climatic and ecological damage caused by impacts and volcanism. The impact had an immediate and direct effect on the dinosaurs, killing a good number of material expelled regionally, as well as globally from the crater that rained across the planet. But the asteroid also hit a region where there were many particularly bad minerals (carbonates and sulfates), and spray-sprayed them, meaning it vaporized them into particles small enough that they could remain airborne for a long time. This material is dark, thus preventing sunlight from reaching the ground, causing prolonged periods of global cooling. This reduced the viability of dinosaur habitats, leading to more deaths later and global mass extinction.
But what about Deccan traps? Scientists find that there was an immediate effect of them, too, by inserting sulfates into the atmosphere. But even though the eruptions lasted a long time, the amount of sunlight-absorbing material they put into the air was small compared to the impact, too small on its own to create a global extinction event.
However, the eruptions also released a large amount of carbon dioxide into the air, which is a greenhouse gas. This has the effect of heating the Earth. At first, impact cooling dominated, but over time that would ease on its own as aerosols left the atmosphere. But the volcanic COtwo emissions would have helped, accelerating warming, providing cleaner habitats for species to fill.
This coincides with previous studies showing that temperatures recovered relatively quickly after impact.
It has been interesting to read these articles on the effects of impact and cheating, watching scientists focus on the effects of each. The idea of an impact extinction was controversial at first, but over time we have learned about the damage that impacts can cause. Then scientists began to think about how Deccan traps fit into the picture, and there have been reports coming and going about whether they were part of the extinction event or had little to do with it. This more recent study shows that they probably did not participate in the extinction, but may have played a role in mitigating the effects later.
I love this. I know that scientists can’t seem to make up their minds, but that’s not the case at all. What happened is that broad strokes were discovered first, and then more work reveals more subtle effects, so it can be difficult to pin down what they are and what they do. But each part of the published research gives us a little more information, a slightly wider view of the image, and eventually (hopefully) the pieces come together to create a better understanding of the events.
It also shows how resilient life is, as well as our planet itself. A 10 kilometer asteroid is a hell of a cannon ball, and although it changed things severely and globally, Earth recovered. Life was not completely erased, and he finally found his way back.
There are lessons here, to be sure. I am sure there is a segment of our population that will take this the wrong way. Sure, all that COtwo That was shot up in the air by volcanism really helped, but that happened for hundreds of thousands of years. Humans are injecting dozens of gigatons of carbon dioxide into our air. every year, which is so fast that the Earth’s ecosphere does not have time to adapt, which is why we are making things much worse.
We are more like the asteroid in this scenario. Nature likes to experiment with catastrophes, but that doesn’t mean we have to.
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