Not all large meteorite impacts can trigger a major change in the planet’s climate in the long term. A University College London (UCL) study of the remains of two space rocks that collided with Earth 35 million years ago shows that the environment remained largely unchanged for the next 150,000 years.
A popular belief about meteorites is that after impact they can generate extensive winters that put life on the planet at risk. The Chicxulub asteroid, which collided 66 million years ago in Yucatán, is a case that reinforces this idea. The impact of the rock is linked to the extinction of the Cretaceous dinosaurs because it launched material into the atmosphere, preventing the passage of sunlight. However, there is evidence to suggest that the Earth’s own volcanic activity during the Cretaceous period was the main trigger for this significant drop in temperature.
The Chicxulub asteroid measured approximately 10 kilometers in diameter. The asteroids studied by UCL had a diameter of between 3 and 5 kilometers, but the width of Mount Everest. The craters they created are located in Siberia and the United States. They rank fourth and fifth on the list of largest impact footprints on Earth. Russia’s so-called Popigai crater is a 100-kilometer scar, while the Chesapeake Bay crater is between 40 and 85 kilometers in diameter.
Despite their dimensions and craters, these meteorites did not change the climate of their surroundings. In research published in the journal Nature Communication Earth & Environmentscientists found that the environment usually remained warm for millennia. The isotopes that formed in the fossils of marine organisms that lived during the years after the impacts were the key.
“We expected the isotopes to shift in one direction or another, which would indicate warmer or colder waters, but this did not happen. These large asteroid impacts occurred and, in the long term, our planet seemed to continue functioning as usual,” said Bridget Wade, co-author of the study and professor of Earth Sciences at UCL.
The samples where the isotopes were searched were 11,000 years apart. On geological time scales, a mountain-sized meteorite might not spell trouble for life. However, the authors warn that, on a human time scale, the crash would be catastrophic. In the following years or decades, the surrounding regions would be radically transformed. “They would create a huge shock wave, a tsunami, there would be widespread fires and large amounts of dust would be sent into the air,” the university statement mentions.
The study also found evidence of other impacts that coincided with the collision of the two meteorites. This could mean that during the Eocene period there was a disturbance in the asteroid belt of the solar system. The Earth, as on other occasions, would have withstood each blow without being disturbed.
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