ICAS external seminar

Andrew Gettelman (NCAR/University of Oxford) "Cloud processes through the looking glass at the intersection of Forcing and Feedback"

ICAS External Seminar: Andrew Gettelman

“Cloud processes through the looking glass at the intersection of Forcing and Feedback”

Preceded by refreshments in the SEE Foyer from 10:30am


Clouds are critical for understanding the historical and future evolution of climate. Clouds are the largest uncertainty in historical climate radiative forcing, due to uncertainties in how anthropogenic aerosols impact cloud processes and ultimately cloud radiative effects. How clouds respond to climate change is the largest uncertainty in climate feedbacks, which determine the future response of the climate system. Cloud forcing and feedback will be explored in the context of the community earth system model (version 2) recently released as part of the CIMP6 process. Forcing and feedback are also key for understanding how CESM2 evaluates very well against current climate and also why CESM2 has a high climate sensitivity, outside of the 'likely' IPCC range. The applicability of these results to other models and generality for the climate system will be explored.


Andrew is broadly interested in climate and specifically the role of clouds in the climate system, and perturbations to clouds through human-induced forcing and feedbacks. His work includes analysis of both data and a range of different atmospheric models, mostly large scale global General Circulation Models. His research has focused recently on cloud microphysics, aerosols and ice phase clouds.

Past research has included extensive studies of the Upper Troposphere and Lower Stratosphere in the tropics and extra-tropics. Including the exchange of air between the stratosphere and the troposphere, with a focus on water vapour. The exchange of air (and especially water vapour) across the tropopause is of fundamental importance for predicting the future chemistry of the stratosphere, and the future evolution and recovery of the stratospheric ozone layer. Water vapour in this region also has important radiative feedbacks on climate. Understanding water vapour variations and trends has led him to expand his research to understanding cloud processes and their role in the climate system.