[Rockhounds] Chicxulub impact winter sustained by fine silicate dust

[Kreigh Tomaszewski]

The Chicxulub impact is thought to have triggered a global winter at the
Cretaceous-Palaeogene (K-Pg) boundary 66 million years ago. Yet the
climatic consequences of the various debris injected into the atmosphere
following the Chicxulub impact remain unclear, and the exact killing
mechanisms of the K-Pg mass extinction remain poorly constrained. Here we
present palaeoclimate simulations based on sedimentological constraints
from an expanded terrestrial K-Pg boundary deposit in North Dakota, United
States, to evaluate the relative and combined effects of impact-generated
silicate dust and sulfur, as well as soot from wildfires, on the
post-impact climate. The measured volumetric size distribution of silicate
dust suggests a larger contribution of fine dust (~0.8–8.0 μm) than
previously appreciated. Our simulations of the atmospheric injection of
such a plume of micrometre-sized silicate dust suggest a long atmospheric
lifetime of 15yr, contributing to a global-average surface temperature
falling by as much as 15°C. Simulated changes in photosynthetic active
solar radiation support a dust-induced photosynthetic shut-down for almost
2 yr post-impact. We suggest that, together with additional cooling
contributions from soot and sulfur, this is consistent with the
catastrophic collapse of primary productivity in the aftermath of the
Chicxulub impact.
https://www.nature.com/articles/s41561-023-01290-4