NH14B-04
Climatic Effects of Medium-Sized Asteroid Impacts on Land

Monday, 14 December 2015: 16:45
104 (Moscone South)
Charles Bardeen1, Rolando R Garcia1, Owen B Toon2, Bette L Otto-Bliesner1 and Eric T Wolf3, (1)National Center for Atmospheric Research, Boulder, CO, United States, (2)Univ Colorado Boulder, Boulder, CO, United States, (3)University of Colorado at Boulder, Boulder, CO, United States
Abstract:
Using the Community Earth System Model (CESM), a three-dimensional coupled climate model with interactive chemistry, we have simulated the climate response to a medium-sized (1 km) asteroid impact on the land. An impact of this size would cause local fires and may also generate submicron dust particles. Dust aerosols are injected into the upper atmosphere where they persist for ~3 years. Soot aerosols from fires are injected into the troposphere and absorb solar radiation heating the air which helps loft the soot into the stratosphere where it persists for ~10 years. Initially, these aerosols cause a heating of over 240 K in the stratosphere and up to a 70% reduction in downwelling solar radiation at the surface. Global average surface temperature cools by as much as -8.5 K, ocean temperature cools by -4.5 K, precipitation is reduced by 50%, and the ozone column is reduced by 55%. The surface UV Index exceeds 20 in the tropics for several years. These changes represent a significant hazard to life on a global scale. These results extend the work of Pierazzo et al. (2010), also using CESM, which found a significant impact on stratospheric ozone, but little change in surface temperature or precipitation, from a 1 km asteroid impact in the ocean.