The North Pole, in turn, victim of a hole in the ozone layer

For several weeks, scientists from the German Aerospace Center have noted “a sharp reduction in ozone concentrations in the Arctic”, explains in a press release in early April the European Space Agency. Thanks to the Copernicus Sentinel-5P satellite, they observed in March the creation of a hole in the ozone layer above the North Pole, an exceptional phenomenon due in particular to unusually low temperatures in the Arctic.

This ozone hole should close in mid-April, according to scientists’ forecasts.

A rare phenomenon in the Arctic

“From my point of view, this is the first time that we can speak of a real ozone hole in the Arctic”, explains to the scientific journal Nature Martin Dameris, of the German Aerospace Center.

In the past, ozone mini-holes have already been spotted above the North Pole, but they are usually not as big as this one. “The ozone hole we are observing over the Arctic this year has a maximum extension of less than a million square kilometers,” said Diego Loyola of the German Aerospace Center to the European Space Agency (ESA). .

It’s usually at the South Pole as large holes in the ozone layer are regularly observed. However, the fault observed on the Arctic side is nothing compared to “the Antarctic hole, which can reach a size of around 20 to 25 million km2”, underlines Diego Loyola.

How was this ozone hole created?

The ozone layer is located in the stratosphere and protects life on Earth from solar ultraviolet rays. The ozone hole is partly “driven by extremely cold temperatures, below -80 ° C”, writes the ASE, but also by the emanation of substances emitted by man such as chlorofluorocarbons, such as chlorine and bromine. Sunlight and wind fields also play a role in this phenomenon.

“Every year in the Antarctic winter, freezing temperatures allow high-altitude clouds to gather over the South Pole. Chemicals, including chlorine and bromine, which come from refrigerants and other industrial sources, trigger reactions on the surfaces of these clouds that eat away at the ozone layer, “explains Nature.

This year, strong winds circulating around the North Pole have thus created in the Arctic “a polar vortex”, that is to say a “circular vortex of stratospheric winds” explains the ASE. These winds were the coldest recorded since 1979 on this pole, and caused particularly low temperatures. “At the end of the polar winter, the first sunlight on the North Pole triggered this unusually large decrease in ozone,” continues ASE.

Should we worry about it?

This ozone hole does not seem to be a threat, however, explains to Nature Markus Rex, scientist at the Alfred Wegener Institute in Potsdam (Germany). Ozone re-establishes as temperatures rise, and the polar vortex disappears, and scientists predicted the hole would close in mid-April.

Difficult for the moment to say what part human activity took in the creation of this ozone hole, because the atmospheric conditions in this area of ​​the world were particularly unusual.

In order to limit the impact of man in the creation of these phenomena, 24 countries signed in 1987 the Montreal Protocol, promising to ensure “the protection of the ozone layer by the gradual elimination with the global scale of ozone-depleting substances (ODS) “, such as bromine and chlorine, explains the Canadian government website. This agreement is considered to be fruitful because it has contributed to considerably reducing the breach opened in Antarctica: the size of the ozone hole of the South Pole in November 2019 was the smallest measured in 35 years.

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