An apocalyptic dust plume killed off the dinosaurs, study says

By Carolyn Y. Johnson
October 30, 2023 at 12:00 p.m. EDT

The mighty dinosaurs may have been done in by dust, according to a new study in Nature Geoscience. ... For decades, scientists have known that a giant asteroid smashed into what is now the Yucatán Peninsula roughly 66 million years ago. Most experts agree the event triggered a mass extinction that wiped out three-quarters of all species, including almost all the dinosaurs. ... But precisely how the impact led to an apocalypse has remained unsettled, with much attention focused on the “impact winter” that occurred afterward — a period of cold, global darkness.

In 1980, scientists posited that the asteroid kicked up a big cloud of pulverized rock dust that starved plants of sunlight. But more recent investigations focused on sun-blocking soot from the initial impact and subsequent global wildfires, or on long-lived sulfur aerosols released by the cataclysm.

The question of how the sun was blocked, and for how long, has been critical to tease out because it shaped the evolution of life on the planet in fundamental ways. A prolonged period of darkness that shut down plants’ ability to turn sunlight into energy could have led to the collapse of the entire food chain. Understanding how life responded and, in some cases, outlasted such an extreme climatic event may provide insight into future extinctions.

For the new study, researchers coupled computer simulation with an analysis of sediment layers at the Tanis paleontology site, which preserves the aftermath of the Chicxulub impact in extraordinary detail. The work reveals that a massive plume of fine-grained dust blanketed the planet and would have lingered in the atmosphere for 15 years, cooling Earth’s surface by 60 degrees and shutting down photosynthesis for two years.

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By Carolyn Y. Johnson
Carolyn Johnson is a science reporter. She previously covered the business of health and the affordability of health care to consumers. Twitter https://twitter.com/carolynyjohnson