It's been firmly established that the extinction of the dinosaurs (save birds) is directly associated with the major asteroid impact event at Chicxulub almost 66 million years ago. The precise mechanism that causes the worldwide extinction has never been firmly established however. A leading hypothesis is the "impact winter" scenario where dust and soot from the impact blocked so much sun that the Earth's temperature plummeted and its ecosystems were devastated.
A new study on PNAS has provided the first direct evidence of this "impact winter" and the havoc it wreaked immediately following the impact.
Maybe the board's YEC expert could explain this data in his scenario since he is on record as claiming the Chicxulub impact never happened.
A new study on PNAS has provided the first direct evidence of this "impact winter" and the havoc it wreaked immediately following the impact.
Rapid short-term cooling following the Chicxulub impact at the Cretaceous–Paleogene boundary
Vellekoop et al
PNAS May 12, 2014, doi: 10.1073
Abstract: The mass extinction at the Cretaceous–Paleogene boundary, ∼66 Ma, is thought to be caused by the impact of an asteroid at Chicxulub, present-day Mexico. Although the precise mechanisms that led to this mass extinction remain enigmatic, most postulated scenarios involve a short-lived global cooling, a so-called “impact winter” phase. Here we document a major decline in sea surface temperature during the first months to decades following the impact event, using TEX86 paleothermometry of sediments from the Brazos River section, Texas. We interpret this cold spell to reflect, to our knowledge, the first direct evidence for the effects of the formation of dust and aerosols by the impact and their injection in the stratosphere, blocking incoming solar radiation. This impact winter was likely a major driver of mass extinction because of the resulting global decimation of marine and continental photosynthesis.
Vellekoop et al
PNAS May 12, 2014, doi: 10.1073
Abstract: The mass extinction at the Cretaceous–Paleogene boundary, ∼66 Ma, is thought to be caused by the impact of an asteroid at Chicxulub, present-day Mexico. Although the precise mechanisms that led to this mass extinction remain enigmatic, most postulated scenarios involve a short-lived global cooling, a so-called “impact winter” phase. Here we document a major decline in sea surface temperature during the first months to decades following the impact event, using TEX86 paleothermometry of sediments from the Brazos River section, Texas. We interpret this cold spell to reflect, to our knowledge, the first direct evidence for the effects of the formation of dust and aerosols by the impact and their injection in the stratosphere, blocking incoming solar radiation. This impact winter was likely a major driver of mass extinction because of the resulting global decimation of marine and continental photosynthesis.
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