Modeling Extreme Events in the Earth System


  • Climate models represent an excellent test bed to examine low probability but high impact events and scenarios. This talk will focus on 3 extreme forcings of the Earth climate system: one that happened, one that we avoided, and one that we hope to avoid. Approximately 74,000 years ago Mt. Toba erupted in Indonesia sending several gigatons of sulfur dioxide gas into the atmosphere, which over time converted to sulfate aerosol and impacted Earth's climate. Thanks to the Montreal Protocol and its subsequent amendments the world has avoided dealing with the impacts of an unrestrained increase in chlorofluorocarbons (CFCs) on the ozone layer and climate. Modeling of the continued increase in CFCs in the 21st century show the possible path we avoided. Finally, I will discuss simulations of the black carbon aerosol impact on climate resulting from massive fires initiated by nuclear conflict scenarios, a path we hope to avoid. I will highlight some of the surprising findings and lessons learned from these simulations.