CFSeminar: Dr. Douglas MacMartin (Cornell University), "Simulation and Design of Stratospheric Aerosol Geoengineering"

Tuesday, April 25, 2017 at 12:00pm

Frank H. T. Rhodes Hall, 178

Abstract:  Reducing future CO2 emissions is unlikely to be sufficient to avoid significant climate change. However, it may be possible to limit climate damage through climate engineering - approaches such as adding sulfate aerosols to the stratosphere to reflect some sunlight and cool the planet. I will talk about how to simulate this, using coupled chemistry-climate models that include not only the atmosphere and ocean circulation, but also aerosol microphysics, aerosol coupling with stratospheric dynamics, and stratospheric chemistry interactions. Furthermore, the climate response to aerosol injection depends on the latitude at which aerosols are added, providing the potential for design to improve outcomes. With collaborators at NCAR and PNNL, we explored how the climate response depends on injection latitude, demonstrated that three spatial degrees of freedom can be achieved by appropriately combining injection at different locations, and finally wrapped a feedback loop around the climate model that adjusts injection amounts at different latitudes to simultaneously manage multiple climate objectives despite all of the uncertainty, nonlinearity, and variability in the climate model simulation. Of course, this research leads to more open questions, such as how well we can design geoengineering, how to assess uncertainty in model projections, how to govern this technology, and whether or not this is a good idea in the first place.

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