About 66 million years ago, an asteroid approximately 10 km in diameter hit the area of today’s Yucatan Peninsula, releasing energy equivalent to 100 trillion tons of TNT.
Scientists have long wondered how this event caused rapid climate change. Some point to sulfur particles from evaporated sedimentary rocks, others to the soot of global fires or dust from Yucatan rocks pulverized by the impact.
New research suggests that the most deadly effect of the impact was dust. While soot and sulfur contributed to global darkness and a long winter that halted photosynthesis for almost two years, fine granite dust pulverized by the impact lingered in the atmosphere for up to 15 years. The asteroid impact led to an extinction spiral that killed 75%. all earthly species.
According to paleoclimate simulations of the Cretaceous period, dust spread across the planet within a few days after the meteorite fell.
– research leader Cem Berk Senel, a researcher with a PhD in planetary science at the Royal Observatory in Belgium, told the Live Science scientific portal.
The space rock that hit Earth at the end of the Cretaceous period (145-66 million years ago) left behind a crater 180 km wide and 20 km deep. Material in this abyss quickly escaped into the atmosphere.
Senel and his colleagues used data from the Tanis site in North Dakota. Scientists measured the size of dust grains in a 1.3-meter-thick layer to determine what was thrown into the atmosphere by the impact. They then fed this information into a computer model of the global atmosphere. The simulation suggested that within about a week, dust grains ranging from about 0.8 to 8 micrometers in diameter were spread across the globe. These particles are smaller than the diameter of a typical human hair and can easily enter the lungs.
It took plants at least four years to begin photosynthesizing at the rate seen before the impact, with scientists estimating that about half of plant species became extinct. However, they still fared better than animals because the seeds could wait dormant for better conditions to germinate again.
While sulfur particles began falling out of the atmosphere in about 8.5 years, fine dust particles could remain in the atmosphere for 15 years.
– Senel pointed out.
Clay Tabor, a paleoclimatologist at the University of Connecticut who was not involved in the research, said for Live Science that the results were intriguing but not conclusive. Different studies used different climate models, which may have influenced the results, and differences between the models used may explain disagreement among researchers on whether soot or dust had the greatest global impact.
– he said.
2023-10-31 05:14:25
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