Joint Seminar: On the role of stratospheric ozone chemistry as a climate feedback

Interactive ozone chemistry is commonly neglected in state-of-the-art climate models involved in future climate projections; the impact of this simplification on the modeled response to external forcings is still unclear. Inter-model differences in the treatment of the coupling between stratospheric ozone, circulation and climate could be a source of inter-model uncertainty in future projections. By carrying out model simulations from the Community Earth System Model (CESM), I carefully quantify the effect of coupling the stratospheric ozone chemistry onto the model's sensitivity to solar and anthropogenic greenhouse gases (GHGs). I accomplish this by using a version of the model, which allows coupling and de-coupling stratospheric ozone chemistry, without altering the dynamical core and physical parameterizations. This model offers the unprecedented opportunity of assessing the importance of the stratospheric chemistry feedbacks, an their importance for the determination of climate sensitivity. I will show that the inclusion of a coupled stratospheric chemistry - and thus interactive ozone - significantly reduces the model response to both GHGs and solar forcing, albeit through two different mechanisms. According to these findings, stratospheric ozone responses yield an important and yet undocumented negative feedback in the climate system. Finally, I will show results from climate change simulations performed with four different chemistry-climate models, highlighting sources of inter-model spread in the ozone response, and thus in the magnitude of the ozone feedback.

Datum

19.04.2017

Uhrzeit

13:30 Uhr

Ort

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

ReferentIn

Gabriel Chiodo, Columbia University

Chair

Hauke Schmidt

Zur Übersicht