Update on Global ozone: past, present, and Future
Résumé
is chapter deals with the evolution of global ozone outside of the polar regions. e increase of ozone-depleting substance (ODS) concentrations caused the large ozone decline observed from the early satellite era (circa 1980) to the mid-1990s. Since the late 1990s, concentrations of ODSs have been declining due to the successful implementa- tion of the Montreal Protocol. Ozone concentrations show latitudinally dependent increases in the upper stratosphere for the 2000–2016 period; changes in other parts of the stratosphere are not yet statistically signi cant. A new suite of model simulations con rms previous results for the upper stratosphere that about half of the observed increase is associated with declining ODSs. Ozone column trends are likewise positive but not generally statistically signi cant. eir overall evolution is, however, compatible with the decline in equivalent e ective stratospheric chlorine (EESC).
Over the next decades, we expect increasing global mean stratospheric ozone columns, as ODSs continue to decline. Emissions of greenhouse gases (GHGs), especially carbon dioxide (CO2 ), methane (CH4 ), and nitrous oxide (N2O), will also a ect the evolution of global stratospheric ozone, particularly in the second half of the 21st century, when ODS concentrations are expected to be low.
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