INSIGHTS INTO K-PG EXTINCTION MECHANISMS USING AN EARTH SYSTEM MODEL

Many experts believe that the Chicxulub impact event at the end of the Cretaceous was the primary driver of the Cretaceous-Paleogene mass extinction. Nevertheless, debate continues about what impact-driven processes ultimately caused the extinction. Ambiguity concerning forcings and feedbacks has allowed for the perpetuation of many extinction hypotheses, including rapid cooling and cessation of photosynthesis from aerosol injections, acidification from gas release, burning from a thermal pulse, ultraviolet radiation from ozone destruction, and warming from greenhouse gas emissions. Most likely, the kill mechanism was a combination of processes that acted at varying timescales, and with different forcings being largely responsible for extinctions among distinct ecosystems, for individual taxa within a single ecosystem, and between similar ecosystems located at varying distances from the Chicxulub impact.

A reason for the ongoing discussion about extinction mechanism comes from our poor understanding of Earth system responses to extreme perturbations. Accurate simulation of the Chicxulub impact is a major challenge because it requires altering an Earth system model for both deep time climate and extreme perturbations. Here, we adapt an Earth system model, which includes an explicit aerosol resolving scheme and an ocean biogeochemistry module, to simulate many of the responses across the K-Pg boundary. These simulations will allow for direct comparison with sedimentological, paleontological, geochemical, and climatological records, providing new insight into the mechanisms responsible for the K-Pg extinction. In this presentation, we will use a series of Earth system model sensitivity tests to explore what aspects of the asteroid impact were most devastating to life.