Tuesday, October 29, 2013
IST Lunch Bunch
Geoengineering the Earth's Climate (The World's Largest Control Problem!)
Doug MacMartin, Senior Research Associate in Computing and Mathematical Sciences, Caltech
"Solar geoengineering" refers to an intentional, large-scale manipulation of the Earth's incoming solar radiation that is designed to offset some effects of anthropogenic greenhouse gases and reduce the associated risks from climate changes. For example, injecting aerosols into the stratosphere would deflect some incoming sunlight back to space and thus cool the planet.
Nature has provided occasional analogues in the form of large volcanic eruptions: the planet briefly cooled by roughly 0.5 degrees after the eruption of Mt. Pinatubo in 1991. Geoengineering raises significant questions, ranging from concern over "winners and losers" that might result from regional inequalities (who gets to set the thermostat?), to the
irreducible uncertainty regarding the climate effects (how do we engineer a system we don't understand?). Control theory is an important tool in addressing these questions in order to better evaluate geoengineering, indeed this can be understood as literally the world's largest control problem! In particular, (a) feedback of the observed climate state can be used to manage significant uncertainty in both the radiative forcing and the climate's dynamic response to this forcing, and (b) optimization can be used to minimize regional disparities as well as side-effects from the geoengineering implementation. In this talk, I will give an overview of geoengineering, present recent progress on control for this problem and discuss open research gaps.