The ozone hole is back to its old ways: the largest and deepest in recent years

After a season in which the hole in the ozone layer in the Southern Hemisphere was reduced to its smallest size ever observed, this 2020 ozone has been reduced again to levels that were not seen years ago, as confirmed by scientists from the European agency Copernicus.

In some areas the ozone concentration is close to zero. The meteorological conditions, with a very stable and cold polar vortex, have favored the destruction of ozone.

“The ozone hole in 2020 looks like the hole in 2018, which was also quite a large hole, and is definitely on top of those seen in the last fifteen years or so,” says Vincent-Henri Peuch, Director of the Service. Copernicus Atmosphere Watch. “With sunlight returning to the South Pole in recent weeks, we saw continued ozone depletion in the area. After the unusually small and brief ozone hole in 2019 – which was triggered by special weather conditions – we are posting a fairly large one again this year, confirming that we have to continue to enforce the Montreal Protocol that bans emissions of ozone-depleting chemicals. “

The ozone column, the concentration of ozone in the stratosphere, has reached record lows this month.

Bad news for those who raised the bells to the flight last year, when the ozone hole dropped to its all-time high due to an extreme sudden stratospheric warming event. It was then celebrated by many as a great success of the Montreal Protocol.

This year’s hole shows that reality is more complicated.

Although the ozone hole is subject to significant annual variability, to get an idea we have put together the image of the ozone hole of 2020 with that of 2019 on the same dates. It can be seen that not only the surface is much lower, but also the concentration (the red color indicates a greater presence).

The Atmosphere Monitoring Service of the European Copernicus network constantly measures the ozone conditions in the atmosphere with satellite data, checking them with the measurements of gloos probe and is able to create forecasts on its evolution.

How is the hole in the ozone layer formed?

The hole in the ozone layer forms every year in the spring, when the first rays of the sun reach the poles. Chemical compounds banned by the Montreal Pact, such as chlorine (CFC) and bromine-containing substances, accumulate inside the polar vortex.

With the extreme temperatures of the polar vortex (the stratospheric current that keeps cold air confined at the poles), stratospheric clouds form that promote ozone-depleting chemical reactions.

Chemical compounds remain inactive until they are hit by the first rays of the sun. “Energy from the sun releases chemically active chlorine and bromine atoms into the vortex that rapidly destroy ozone molecules, causing the hole to form,” Copernicus explained in a statement.

These types of conditions are more common in the southern hemisphere, but this year the largest and most stable hole in the ozone layer at the North Pole occurred.

What consequences does it have for life on earth?

The ozone hole is a shield against ultraviolet rays. The main consequence of the ozone hole is a greater exposure to these radiations that can cause skin cancer and eye problems in areas that are unprotected by the layer.

In addition, recent research suggests a link between the ozone hole and the marine and atmospheric currents responsible for the climate in the medium and long term.

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