WMO Assessment 2022: Chapter 3 Summary

Efforts for the 2022 Scientific Assessment on Ozone Depletion published by the World Meteorological Organization are well underway. Chapter 3, titled “Update on Global Ozone: Past, Present, and Future”, presents our current understanding of global ozone outside of the polar regions and this talk summarizes some of the highlights and changes from the previous Assessment in 2018. Since the last Assessment, the longer observational records show a small, significant increase in near-global total column ozone. A small significant increase in total column ozone is also seen in the mid-latitudes of both hemispheres, but not yet the tropics. Different processes operating at different altitudes complicate the interpretation of the overall total column trend. However, a significant increase in upper stratospheric ozone noted in the previous Assessment continues, driven by declines in ozone depleting substances and increases in greenhouse gases. Model simulations support our understanding of these trends.

Over the coming century, we expect an increase in global stratospheric ozone as the concentrations of ozone depleting substances decline. The future evolution for different latitudes and vertical levels depends on the future concentrations of greenhouse gases and precursors of tropospheric ozone., These other influences may lead to total ozone column levels that remain below 1980 values even after ozone depleting substance concentrations have recovered to pre-1980 levels.