Climate Change Impacts of Antarctic Ozone Recovery

Observed and modeled patterns of Southern Hemisphere (SH) stratospheric temperature, winds and geopotential height in the late 20th century (1979–1998) and beyond (1999–2018) are compared. Pre-2000 observed Antarctic ozone decreases lead to stratospheric cooling and a strengthening of the stratospheric westerly winds and an increased tendency toward the positive phase of the Southern Annular Mode; this trend is followed by opposite-signed (i.e., “mirrored”) patterns due to ozone increases and warming post-2000. An interactive chemistry-climate model forced by changes in anthropogenic ozone depleting substances produces broadly similar mirrored features. Overall, the results support findings of the healing of the Antarctic ozone hole, as well as previous projections of the impacts of ozone recovery. We investigate the roles of dynamics, chemistry, and radiation, and their interplay in order to fully understand the causes of observed stratospheric circulation changes that accompany the recent temperature and ozone changes. Implications for trends in SH surface climate, as well as the interplay between ozone and greenhouse gas forcings are also investigated.