Dino-killing asteroid darkened earth for two years: Study

An asteroid that wiped off dinosaurs 66 million years ago would have also plunged earth into darkness for nearly two years, according to new research.

The 10-km-wide asteroid attack caused global wildfires that released tremendous amounts of soot in the atmosphere, which absorbed light and potentially blocked the process of photosynthesis for more than a year-and-a-half.

The attack also dramatically changed the climate of earth -- cooling the surface and heating the upper atmosphere, with potentially devastating effects -- and contributed to the mass extinction that marked the end of the age of dinosaurs, the research showed.

According to estimates, more than three-quarters of all species on earth, including all non-avian dinosaurs, disappeared at the boundary of the Cretaceous-Paleogene periods -- an event known as the K-Pg extinction.

The collision would have also triggered earthquakes, tsunamis and even volcanic eruptions.

"The extinction of many of the large animals on land could have been caused by the immediate aftermath of the impact but animals that lived in the oceans or those that could burrow underground or slip underwater temporarily could have survived," said lead researcher Charles Bardeen, scientist at the US National Center for Atmospheric Research (NCAR).

"Our study picks up the story after the initial effects -- after the earthquakes and the tsunamis and the broiling. We wanted to look at the long-term consequences of the amount of soot we think was created and what those consequences might have meant for the animals that were left," Bardeen added.

For the new study, published in the journal Proceedings of the National Academy of Sciences, the team used a computer model to understand how earth's conditions might have looked at the end of the Cretaceous Period.

The findings could be useful for other types of studies, including modelling a "nuclear winter" scenario. Like global wildfires millions of years ago, the explosion of nuclear weapons could also inject large amounts of soot into the atmosphere, which could lead to a temporary global cooling, the researchers said.

--IANS

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