SIMULATING THE K-PG WITH AN EARTH SYSTEM MODEL

The Cretaceous-Paleogene (K-Pg) boundary marks one of the five major mass extinctions in Earth’s history. Many believe this extinction was the result of a large asteroid impact in the Gulf of Mexico, marked by the Chicxulub crater in the present-day Yucatan peninsula. Theoretical and simple modeling works have explored the potential for the Chicxulub impact to cause mass extinction. However, never before has a modern Earth system model been used to simulate the climatic consequences this event. Here, we use a Maastrichtian configuration of the Community Earth System model to investigate the climate responses to the Chicxulub impact. Our model setup allows us to simulate many of the chemical, physical, and dynamical responses to the K-Pg impact, both temporally and spatially. Preliminary results suggest that soot emissions from global fires ignited after the impact results in a complete blocking of sunlight for over two years. Consequently, global temperatures plummet by 16°C, convective precipitation decreases substantially, and Northern Hemisphere sea ice expands to mid-latitudes. Although the entire globe experiences rapid change, the responses are not spatially homogenous. For example, the equatorial Pacific experiences a dramatic reduction in temperature and precipitation while the coast of Antarctica barely cools and precipitation increases slightly. These simulations allow for a better understanding of why some regions and species were able to weather the impact. On a global scale though, our findings are consistent with theory and suggest that an asteroid impact might have been the main driver of the K-Pg extinction.