Trend Stratospheric ozone recovered within the safe space but recovery may be stalling

Summary

The stratospheric ozone layer shields life from harmful ultraviolet radiation and was badly depleted in the late twentieth century by long-lived chemicals such as chlorofluorocarbons. International controls on these substances allowed substantial recovery from the mid-1990s, bringing the global boundary back within the safe space. Average extra-polar ozone now stands at about 286 DU, above the 277.4 DU boundary, which is set at 5 percent below the 1964 to 1980 mean of 292 DU. Levels remain below mid-twentieth-century values, and the report observes the recovery may have plateaued in recent years, with the data series ending in 2022. Nitrous oxide, largely from agriculture, is now the largest remaining ozone-depleting emission, and emerging risks such as re-entering space debris are also discussed. Incomplete recovery or new pressures could again raise risks to health, crops, ecosystems and atmospheric circulation.