Global winter caused by asteroid impact doomed the dinosaurs

New study: Sulphuric gases emitted during the Chicxulub impact 66 million years ago caused a long-lasting global winter that wiped out the dinosaurs and most of Earth’s other species.

A team of scientists studying rock samples in the Gulf of Mexico is providing new evidence about exactly how the dinosaurs were killed off 66 million years ago when a massive asteroid about 10 kilometers wide crashed into Mexico’s Yucatan Peninsula.

Researchers have debated the possible ways the Chicxulub impact could have wiped out most of Earth’s species, with some arguing that tsunamis in the aftermath of the explosion were the main culprit.

Now, researchers led by Professor Joanna Morgan at Imperial College London, make a good case that the specific gases released into the atmosphere by the asteroid impact created a long-lasting global winter that doomed two-thirds of Earth’s species.

The research is published in Geophysical Research Letters.

By analyzing minerals and shatter patterns in the ocean bedrock, the researchers were able to determine the direction taken by the asteroid and its impact speed. According to their calculations, the asteroid crashed into a shallow sea at a speed of about 64,000 kilometers per hour, creating a hole in the ocean floor some 30 kilometers deep.

But the key finding involved the type of rock with which the asteroid collided.

The scientists found that the Gulf of Mexico is covered with a mineral known as anhydrite that releases sulphur when heated. They concluded that gigantic clouds of sulphuric ash released by the Chicxulub asteroid blocked out the sun and produced a devastating global winter, causing many food chains to perish.

The large amount of sulphur-laden climatic gases indicate that “surface temperatures were likely to have been significantly reduced for several years and ocean temperatures affected for hundreds of years after the Chicxulub impact,” write the authors.

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