Stratospheric ozone depletion

The ozone layer in the upper atmosphere protects the Earth from harmful solar ultraviolet radiation. Additionally, ozone plays an important role in atmospheric energy balance. Because of the release of ozone depleting substances (ODS), the ozone layer has substantially declined over the second half of the 20th century.

Since the mid-1990s, thanks to the international agreements limiting ODS release, the ozone layer has largely recovered, and it is expected to stay within the safe limits. The ozone layer depletion and its subsequent recovery had measurable effects on atmospheric circulation, particularly in the Southern Hemisphere.

Control Variables

The Planetary Boundary for Stratospheric Ozone Depletion tracks the amount of ozone (O₃) in the upper atmosphere, where it forms a protective layer that blocks most of the Sun’s harmful ultraviolet (UV) radiation. Thanks to the Montreal Protocol, which phased out ozone-depleting chemicals like CFCs, the ozone layer has been recovering. Overall, it remains within the safe zone, but the recovery is uneven and still vulnerable. New pressures are emerging from rising nitrous oxide (N₂O) emissions and increasing space activity, both of which could slow or even reverse the gains made over the past decades.

Impacts

A thinner ozone layer means more UV radiation reaches the ground. This affects people, ecosystems, and even weather patterns. While the most dramatic ozone hole over Antarctica is slowly closing, the ozone layer’s health remains essential for life and climate stability.