Chicxulub impact winter sustained by fine silicate dust

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.

Peer Review, Impact Factor