We need to continue enforcing the Montreal Protocol banning emissions of ozone depleting chemicals.
The hole in the ozone layer over Antarctica is one of the largest and deepest in recent years, academics have said.
Scientists from the European Union’s Copernicus Atmosphere Monitoring Service (CAMS) say the hole which forms each year over the South Pole has reached its maximum size for 2020 as one of the biggest in recent years.
The return of a large hole after an “unusually small and short-lived” ozone hole in 2019 shows the need to continue enforcing the global Montreal Protocol, which banned chemicals such as CFCs that deplete ozone, experts said.
The stratospheric ozone layer acts as a shield, protecting from potential harmful ultraviolet radiation, but substances created by humans have caused an annual thinning in the layer, known as the ozone hole.
These chlorine and bromine-containing substances accumulate within the polar vortex – an area of low pressure in the region – where temperatures can fall to below minus 78C (minus 108.4F) and causing the formation of stratospheric clouds which cause cheical reactions that deplete ozone.
As the sun rises over the pole after the winter darkness, the sun’s energy releases chemically-active chlorine and bromine atoms in the vortex which rapidly destroy ozone molecules, causing the hole to form.
CAMS is run by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Commission and uses computer models of the atmosphere combined with satellite data and in-situ monitoring to assess the state of the ozone layer.
Vincent-Henri Peuch, director of Copernicus Atmosphere Monitoring Service at ECMWF, said: “There is much variability in how far ozone hole events develop each year.
“The 2020 ozone hole resembles the one from 2018, which also was a quite large hole, and is definitely in the upper part of the pack of the last fifteen years or so.
“With the sunlight returning to the South Pole in the last weeks, we saw continued ozone depletion over the area.
“After the unusually small and short-lived ozone hole in 2019, which was driven by special meteorological conditions, we are registering a rather large one again this year, which confirms that we need to continue enforcing the Montreal Protocol banning emissions of ozone depleting chemicals.”
Emily Beament is the PA environment correspondent.