Quantifying the Release of Climate‐Active Gases by Large Meteorite Impacts With a Case Study of Chicxulub

Potentially hazardous asteroids and comets have hit Earth throughout its history, with catastrophic consequences in the case of the Chicxulub impact. Here we reexamine one of the mechanisms that allow an impact to have a global effect—the release of climate‐active gases from sedimentary rocks. We use the SOVA hydrocode and model ejected materials for a sufficient time after impact to quantify the volume of gases that reach high enough altitudes (> 25 km) to have global consequences. We vary impact angle, sediment thickness and porosity, water depth, and shock pressure for devolatilization and present the results in a dimensionless form so that the released gases can be estimated for any impact into a sedimentary target. Using new constraints on the Chicxulub impact angle and target composition, we estimate that 325 ± 130 Gt of sulfur and 425 ± 160 Gt CO2 were ejected and produced severe changes to the global climate. Plain language Summary Potentially hazardous asteroids and comets have hit Earth throughout its history, with catastrophic consequences in the case of the Chicxulub impact 66 Myr ago. Here we reexamine one of the mechanisms that allow an impact to have a global effect—the release of climate‐active gases from terrestrial sedimentary rocks after the high‐velocity impact. We estimate that 325 ± 130 Gt of sulfur and 425 ± 160 Gt CO2 were ejected into the atmosphere at velocities > 1 km/s. These numbers have to be used in global climate models to quantify possible changes of solar irradiation, surface temperature, and duration of stressful conditions for biota. Key Points We use a hydrocode to model shock pressures, ejection velocities, and amount of gases released from sedimentary rocks after large impacts We use new constraints on impact angle and target composition to improve estimates of the gases released by the Chicxulub impact We investigate the effects of sediment porosity, submergence under water, and uncertainties in devolatilization pressures on our estimates