13.6 Possible impact of a large increase of ozone depleting substances on Northern Hemisphere climate

Friday, 12 June 2009: 12:00 PM
Pinnacle A (Stoweflake Resort and Confernce Center)
Judith Perlwitz, CIRES/Univ. of Colorado and NOAA-ESRL, Boulder, CO; and R. L. Fogt, P. A. Newman, L. Oman, and S. Pawson

The Northern Hemisphere (NH) climate response to uncontrolled emissions of ozone-depleting substances (ODSs) at an annual increase of 3% (so called World Avoided, WA by the Montreal Protocol) is investigated. To determine possible tropospheric climate impacts of the Montreal Protocol, we analyze a WA simulation and an ensemble of reference simulations for the period of 2001 to 2049 from a coupled chemistry climate model. We found a significant shift of the Northern Hemisphere Annular Mode towards its positive phase during the late spring to fall. We show that greenhouse gas induced warming over the NH continents would be amplified by up to 100 % and the storm tracks would move poleward with large increases of intensity suggesting an increase of high impact storm events. Thus, the results of this study suggest that the Montreal Protocol possibly avoided strong NH climate changes.
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