Stratospheric ozone loss by very short-lived substances

The Montreal Protocol limits anthropogenic emissions of ODSs. These ODSs are chemically stable in the troposphere where they are emitted, but once transported to the stratosphere, they release chlorine and bromine species that reduce ozone concentrations through chemical reactions. With the success of the Montreal Protocol, the ozone layer is expected to recover to the pre-1980 level over the course of this century, and the first signs of recovery can already be observed. Stratospheric chlorine and bromine loadings have been declining since the 1990s². In accordance with these changes, stratospheric ozone concentrations are slightly increasing, especially in the upper stratosphere and the Antarctic lower stratosphere².