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Impact winter from K/Pg Chicxulub impact confirmed



From: Ben Creisler
bcreisler@gmail.com

A new online paper:


Johan Vellekoop, Appy Sluijs, Jan Smit, Stefan Schouten, Johan W. H.
Weijers, Jaap S. Sinningh Damsté, and Henk Brinkhuis (2014)
Rapid short-term cooling following the Chicxulub impact at the
Cretaceous–Paleogene boundary.
Proceedings of the National Academy of Sciences (advance online publication)
doi: 10.1073/pnas.1319253111
http://www.pnas.org/content/early/2014/05/08/1319253111.abstract?sid=47eb1858-04b8-4976-85a8-01cb49471b22

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.

Significance

Here, for the first time (to our knowledge), we are able to
demonstrate unambiguously that the impact at the Cretaceous–Paleogene
boundary (K–Pg, ~66 Mya) was followed by a so-called “impact winter.”
This impact winter was the result of the injection of large amounts of
dust and aerosols into the stratosphere and significantly reduced
incoming solar radiation for decades. Therefore, this phase will have
been a key contributory element in the extinctions of many biological
clades, including the dinosaurs. The K–Pg boundary impact presents a
unique event in Earth history because it caused global change at an
unparalleled rate. This detailed portrayal of the environmental
consequences of the K–Pg impact and aftermath aids in our
understanding of truly rapid climate change.


News story:
http://news.nationalgeographic.com/news/2014/05/140512-asteroid-impact-winter-science/