In March 2020, coinciding with the outbreak of the COVID-19 disease in Europe, NASA satellites detected a huge hole in the Arctic ozone layer. It is a phenomenon that is more or less usual in the Antarctic winter, since low temperatures cause clouds to accumulate at high altitude and this, combined with the presence of substances such as chlorine and bromine that come from industrial emissions, causes the temporary destruction of ozone in that area. When temperatures rise, the layer recovers.
This phenomenon is less common in the Arctic, which does not usually reach temperatures as low as those recorded at the South Pole, but this winter has been extremely cold in this area. As expected, the increase in temperatures in the stratosphere during the month of April, which culminated in the arrival of ozone-rich air from the inner atmosphere, has produced the complete closure of the hole , as reported by the World Meteorological Organization ( WMO).
Contrary to what many may think, the disappearance of this hole has nothing to do with the decrease in pollution due to mobility restrictions during the coronavirus crisis. However, the human will to change things has been decisive in curbing the destruction of the ozone layer, so necessary to protect us from the sun’s ultraviolet radiation and preserve life on Earth. We are talking about the Montreal Protocol, one of the most successful environmental agreements in history, which was signed in September 1987 with the aim of reducing emissions of substances that attack the ozone layer, with special attention to chlorofluorocarbons. (CFC). Thanks to the ratification of this protocol, the use and emission of these compounds was considerably reduced, although some of them persist in the atmosphere for several decades, and their concentrations are still high enough to cause severe ozone destruction.
Without the Montreal Protocol, ozone depletion would have been much greater, although we must not lower our guard. “The Arctic stratosphere remains vulnerable to ozone-depleting substances linked to human activities,” explained WMO Secretary General Petteri Taalas. “The degree of ozone loss experienced in a particular winter depends on the weather conditions. The ozone loss of 2020 shows that we must remain vigilant and keep continuous observations. “
Will this large hole be noticeable in the Arctic?
During the spring of 2011, a similar ozone depletion phenomenon occurred in the Arctic, with temporary losses of up to 90%. This depletion caused a 60% increase in the UV index in the Canadian Arctic, and an even greater increase in northern Europe.
Each year, based on spring ozone levels, a summer seasonal UV forecast is provided to the public in different countries.
The recovery of the ozone layer
The most recent scientific assessment of ozone depletion carried out by WMO and the United Nations Environment Program shows that in some parts of the stratosphere the ozone layer has recovered at a rate of 1 to 3% per decade since 2000.
At predicted speeds, ozone in the Arctic and northern mid-latitudes is expected to fully recover before mid-century, around 2035, followed by mid-latitudes in the southern hemisphere around mid-century, and that of the Antarctic region that is forecast for the year 2060.
