Evidence for origins of soot emissions from the Chicxulub asteroid impact at the Cretaceous--Paleogene boundary

Carbon particles released by the Chicxulub asteroid impact may have driven climatic changes and extinction across the Cretaceous-Paleogene (K–Pg) boundary. Geologic support for this possibility comes from globally distributed, carbon- rich deposits at K–Pg boundary sites, but whether this carbon originated from near-global wildfires, impact-site combustion, or both remains debated. Here, we simulate K–Pg carbon-emission scenarios with a state-of-the-art Earth system model and compare modeled carbon deposition with geologic records at K–Pg boundary sites. The simulations show that soot from impact-site combustion alone can produce severe cooling and darkness comparable to near-global wildfire scenarios. However, geological records of carbon deposition at K–Pg sites are more consistent with modeled carbon deposition in simulations that include near-global wildfire emissions. Thus, results suggest that soot derived largely from widespread wildfires was likely a primary driver of end-Cretaceous mass extinction.