2023-10-30 18:32:14
The story of the end of the dinosaurs, which science accepts as good, tells that about 66 million years ago a meteorite hit what is now the northwest corner of the Yucatan Peninsula (Mexico). The rock, about 10 km long, hit the Earth with a force equivalent to that of 10 billion atomic bombs like that of Hiroshima, triggering a brutal tsunami and, what was even worse, expelling a fatal cloud of carbon into the atmosphere. debris. With the Sun’s rays blocked, a long global winter wiped out 75% of life on the planet, including the ill-fated dinosaurs.
What’s not clear, however, is which components of that debris played a larger role in the mass extinction. Previous research had pointed to sulfur released during the impact and soot from subsequent forest fires as the main culprits for the cloudy sky.
A new study by a team of Belgian researchers suggests that it was fine silicate dust from pulverized rock that likely caused the global climate to cool and photosynthesis to stop.
Stop in photosynthesis
To assess the role of sulfur, soot, and silicate dust in post-impact climate, the researchers produced paleoclimate simulations based on an analysis of fine-grained material placed in a well-preserved impact deposit from a site in North Dakota. (USA). “We work in many K-Pg sites [el límite Cretácico-Paleógeno] around the world for more than 30 years. The well-preserved Tanis site in North Dakota was ideal to measure the grain size of the K-Pg layer, that’s why we chose it,” Philippe Claeys, professor of Archaeology, Environmental Changes and Geochemistry (AMGC), tells this newspaper. , from the Free University of Brussels, and author of the article published this Monday by the magazine ‘Nature Geoscience’.
The researchers found that the size distribution of the silicate debris (approximately 0.8 to 8.0 micrometers) revealed a larger contribution of fine dust than had previously been appreciated. They then fed the measured size distribution into a climate model and estimated that that fine dust could have remained in the atmosphere for up to 15 years after the event, contributing to global cooling of the Earth’s surface by up to 15°C. They suggest that dust-induced changes in solar radiation may also have disrupted photosynthesis for nearly two years after the impact.
“Fine dust is densely concentrated in the atmosphere and is effective in blocking sunlight and consequently stopping photosynthesis on Earth for up to 2 years. This blocking of sunlight also reduces temperature, along with the presence of sulfur aerosols,” explains Claeys. In his opinion, the stoppage of photosynthesis was the main factor for the catastrophe.
The authors suggest that the role of silicate dust, along with soot and sulfur, would have blocked photosynthesis and sustained a winter shock long enough to cause catastrophic collapse, triggering a chain reaction of extinctions.
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