It was known that an asteroid collision with the coast of present-day Mexico 66 million years ago caused the extinction of three-quarters of the world’s living organisms, including dinosaurs.
But the exact nature of the phenomenon caused by the asteroid Chicxulub has remained a matter of debate, and the latest theories suggest that sulfur from the impact, or soot from massive fires, may have been the reason for blocking out sunlight and plunging the world into a long winter.
A study whose results were published yesterday, Monday, restored momentum to a previous theory that the dust raised by the asteroid darkened the sky for a long period.
Fine silica dust (powdered sand) may have remained in the atmosphere for fifteen years, and the lack of light would have caused average temperatures to drop by up to 15 degrees Celsius, according to the study, the results of which were published in the journal Nature Geoscience.
In the 1980s, Luis and Walter Alvarez, a father and son, talked about the possibility that dinosaurs might have become extinct after an asteroid impact caused climate change by coating the Earth in dust.
The theory was in doubt, until the massive crater created by the asteroid Chicxulub was discovered in present-day Mexico’s Yucatan Peninsula about ten years later.
Ozgur Karatekin, a researcher at the Royal Belgian Observatory, who participated in preparing the study, explained to Agence France-Presse that the theory that sulfur, and not dust, may have changed the climate was widely accepted because it was believed that this dust was not of the appropriate size to “stay in the atmosphere.”
An international team was able to identify dust particles resulting from the asteroid impact found at the Tanis fossil site in North Dakota, United States. Its measurement ranges between 0.8 and 8 micrometers.
By entering their data into climate models similar to those used today, the researchers concluded that this dust played a much larger role than previously estimated.
Simulations revealed that of the total amount of material dropped into the atmosphere, three-quarters were dust, 24% sulfur, and only 1% soot.
The dust particles “completely prevented the photosynthesis process” in the plants for at least a year, leading to a “catastrophic collapse” of the plants, according to Karatekin.
