Impacts of climate change on stratospheric ozone recovery

The impact of increasing greenhouse gases (GHGs) on the “recovery” of stratospheric ozone is examined using simulations of the Goddard Earth Observing System Chemistry‐Climate Model. In this model, GHG‐induced climate change has a large impact on the ozone evolution and when O 3 recovery milestones are reached. The two distinct milestones of “O 3 returning to historical values” and “O 3 being no longer significantly influenced by ozone depleting substances (ODSs)” can be reached at very different dates, and which occurs first varies between regions. GHG‐induced cooling in the upper stratosphere causes O 3 to increase, and O 3 returns to 1980 or 1960 values several decades before O 3 is no longer significantly influenced by ODSs. In contrast, transport changes in the tropical and southern mid‐latitude lower stratosphere cause O 3 to decrease. Here O 3 never returns to 1980 values, even when anthropogenic ODSs have been removed from the atmosphere. O 3 returning to 1960 (or 1980) values should not necessarily be interpreted as O 3 recovery from the effects of ODSs.