[PAOCQ] Brian Soden (University of Miami)

“Weakening the CO2 Greenhouse Effect”

Carbon dioxide is a key greenhouse gas and the dominant forcing agent on both anthropogenic and paleoclimatic time scales. Our understanding of its radiative properties dates back nearly three-quarters of a century, and calculations from that time to today demonstrate a logarithmic dependence of the radiative forcing by CO2 on its concentration, with each doubling of CO2 trapping ~4W/m2 of heat. However, these calculations, by design, neglect to consider how changes in the temperature of the emission level of CO2 alter its potency as a greenhouse gas. The level at which CO2 most efficiently emits to space occurs in the upper stratosphere (~10 hPa), thus processes which influence temperatures in the upper stratosphere can also alter the greenhouse trapping of heat by CO2. This talk will review the influence of stratospheric temperature changes on the radiative forcing by CO2, and discuss how other anthropogenic processes, such as ozone loss, can modulate that forcing. Then I will discuss how the temperature dependence of CO2 radiative forcing might be used as a potential geoengineering strategy to weaken the Earth’s CO2 greenhouse effect.

PAOC Colloquium —

Interdisciplinary seminar series that brings together the whole PAOC (Program in Atmospheres, Oceans, and Climate) community. Seminar topics include all research concerning the physics, chemistry, and biology of the atmospheres, oceans and climate, as well as talks about societal impacts of climatic processes.

Contact: paoc-colloquium-comm@mit.edu