published on 17 September 2019 in air
Ozone depletion at the lowest levels ever
According to scientists at the Copernicus Atmosphere Monitoring Service (CAMS), this year the ozone hole will be particularly small, and may reach one of the lowest levels ever in the past 30 years. According to estimates, in fact, the hole will probably be half as wide as in 2018.
Usually, the Antarctic ozone hole begins to form each year in August, reaches its maximum size in October and then closes again by December. In fact, during the austral spring, the quantity of ozone over Antarctica decreases to around 60%, because the chemical substances that destroy the molecules of ozone (for example, chlorofluorocarbons) are activated by the sunlight that begins to reappear in spring after the long austral winter. This year, the ozone hole was observed to be behaving unusually. Since the beginning of September, the polar vortex – a vortex of cold air in the stratosphere that provides the conditions necessary to destroy the stratospheric ozone and the consequent formation of the Antarctic ozone hole – moved off centre and was weakened by a sudden heating up of the stratosphere. The temperature increase in the upper stratosphere (up to over 40°C above the norm) made the polar vortex unstable and, as a consequence, the expected size of the ozone hole.
Indeed, an attenuation of this phenomenon had already been observed in recent years, due to the entry into force in 1987 of the Montreal protocol, banning the use of the main chemical products that reduce the ozone layer and to the international commitment, with the result that the ozone layer is gradually reforming. Scientists estimate that, by 2060, the levels of Antarctic ozone will return to those recorded prior to 1980.