The impact of an asteroid off Mexico’s coast 66 million years ago, believed to have triggered a mass extinction, including dinosaurs, has been reevaluated in a recent study.
The Chicxulub asteroid’s nature and impact have long been a subject of debate for scholars. Assumptions that sulfur released from the impact or soot from colossal fires blocked sunlight and plunged the world into a prolonged winter were hitherto considered the most plausible explanations.
However, a study released this week has rekindled a previous theory – that dust kicked up by the asteroid obscured the sky for a significant period.
It is posited that fine silica dust and pulverised sand lingered in the atmosphere for about 15 years. The ensuing lack of light plunged average temperatures by up to 15 degrees Celsius, according to the study, which was published in Nature Geoscience.
Father-and-son duo Luis and Walter Alvarez suggested in the 1980s that dinosaurs became extinct after an asteroid impact altered Earth’s climate by shrouding it in dust.
This theory was doubted until the discovery of the massive Chicxulub crater in Mexico’s Yucatan Peninsula, a decade later.
The theory suggesting sulfur, rather than dust, might have altered the climate had gained traction as it was believed this dust didn’t have the right size “to remain in the atmosphere,” said study co-author Ozgur Karatekin, a researcher at the Royal Observatory of Belgium.
An international team successfully identified dust particles resulting from the asteroid’s impact observed in the fossil site of Tanis, North Dakota, USA. They measure between 0.8 and 8 micrometres.
Using current climate models for input, researchers determined that this dust played a much greater role than previously estimated.
The simulations revealed that, of the total amount of matter ejected into the atmosphere, three-quarters was dust, 24% was sulfur, and only 1% was soot.
The dust particles “completely stopped photosynthesis” in plants for at least a year, triggering a “catastrophic collapse of life,” according to Mr. Karatekin.
