This Month in Environmental History: The Ozone Hole
While my childhood is mostly gaps or memories created from thumbing through yearbooks or my dad’s slides, I do have solid memories of my first pair of high-top Air Jordans in the fifth grade and the time I peed my pants taking a standardized test in the first grade. I vaguely remember learning that littering was bad for the environment and, later, in middle school, understanding that my can of hairspray might also be bad somehow and looking for the ‘no CFCs*’ labels on bottles at the drugstore.
It was probably my middle school science class before a teacher mentioned the ozone layer and the subsequent havoc that the human population wreaked on the thin part of Earth’s atmosphere that absorbs a portion of the radiation from the sun.
In May 1985, a group of scientists from a British Antarctic Survey (Cambridge) published a ‘letter’ in the scientific journal Nature titled Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction. (Abstract below)
Translation: the discovery of the (Antarctic) Ozone Hole, thought to be one of the most striking indictors of ozone depletion. According to NASA, the depletion of the ozone layer is recognized as on the Earth’s most important environmental issues.
In October 1985, the area of the ozone hole was measured at 7.25 million square miles. Thirty-seven years later in October 2022, it measured 10.23 million square miles. For reference, the entire continent of North America is just over 9.5 million square miles.
Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction
Abstract: Recent attempts1,2 to consolidate assessments of the effect of human activities on stratospheric ozone (O3) using one-dimensional models for 30° N have suggested that perturbations of total O3 will remain small for at least the next decade. Results from such models are often accepted by default as global estimates3. The inadequacy of this approach is here made evident by observations that the spring values of total O3 in Antarctica have now fallen considerably. The circulation in the lower stratosphere is apparently unchanged, and possible chemical causes must be considered. We suggest that the very low temperatures which prevail from midwinter until several weeks after the spring equinox make the Antarctic stratosphere uniquely sensitive to growth of inorganic chlorine, ClX, primarily by the effect of this growth on the NO2/NO ratio. This, with the height distribution of UV irradiation peculiar to the polar stratosphere, could account for the O3 losses observed.
For more information on Federal (Clean Air Act) and International (Montreal Protocol et al) actions to address Ozone Depletion, visit this site.
*chlorofluorocarbons and other Ozone-Depleting Substances (ODS)
Sources: Farman, J., Gardiner, B. & Shanklin, J. Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction. Nature 315, 207–210 (1985). https://doi.org/10.1038/315207a0
