In a new study published in Nature Geoscience, scientists have suggested that huge amounts of fine silicate dust formed from crushed rock after asteroid impacts may have played a more significant role in the extinction of dinosaurs than originally thought.
Previously, researchers believed that sulfur released after an asteroid landed, as well as soot generated by forest fires, were the main causes of the global winter that killed about 75 percent of all life on the planet, Newsweek writes.
Researchers who evaluated a well-preserved amount of impact deposit recovered from a site in North Dakota found that more dust was released during the impact than previously thought. The dust could have remained in the atmosphere for 15 years, contributing to a 15-degree Celsius cooling of the Earth.
The dust could also have affected solar radiation, which in turn would have stopped photosynthesis for two years after the impact.
"This is the first time we are creating a paleoclimate model that takes into account actual measurements of the size of the dust obtained in North Dakota," said Philippe Kleis, a geologist, planetary scientist and geochemist, professor at the Free University of Brussels.
"The very small particles we found have a very long atmospheric residence time, up to 15 years, which is actually longer than the sulfur components. Such fine silicate dust, formed from deeper layers inside the rock, also played an important role in cooling the climate and stopping photosynthesis, which led to the death of non-avian dinosaurs," he added.
The volume of dust was enormous, said Kleis, measuring up to 2,000 gross tons. It was the most effective element in blocking photosynthesis on land and oceans for two years, he said.
"The earth is significantly cooled by the combined effects of sulfur, soot and dust, and after five years the effect of sulfur becomes less significant, but dust and soot from a forest fire remain active for at least 15 years," he said.
The scientist added that silicate dust is the most effective "blocker" of photosynthesis. It makes the atmosphere opaque to sunlight, interfering with the photosynthetic process of plants.
"Therefore, there is no more food for herbivores and carnivores... Our model shows that it will take two years for photosynthesis to resume," the expert said.
This study is an important milestone in understanding the extinction of dinosaurs. It shows that silicate dust was a more significant factor than previously thought and that it played a key role in the destruction of these huge reptiles.
As a reminder, scientists explained why the water in the sea is salty, but the fish in it are not.
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