Atmosphere Ocean Science Colloquium

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Why has the tropical lower stratosphere stopped cooling for the last 20 years?

Speaker: Lorenzo Polvani, Columbia

Location: Warren Weaver Hall 1302

Date: Wednesday, May 2, 2018, 3:30 p.m.

Synopsis:

The cooling of the stratosphere is an important fingerprint of CO2 on the climate system.  This stratospheric signature of CO2, however, is confounded by the presence of ozone-depleting substances (ODS). The talk will summarize the latest observations and, with simple arguments and with the help of ensembles of chemistry-climate model integrations, demonstrate the crucial role of ODS not only on stratospheric temperature trends, but also on the entire large-scale circulation of the stratosphere.  The impact of the Montreal Protocol on the detection of the vertical fingerprint of carbon dioxide on atmospheric temperatures will also be discussed.