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March 25, 2020
The largest hole in the ozone layer ever observed above the North Pole has recently emerged.
Hole in the ozone layer from 1979 to 2013
A hole has formed in the ozone layer above the North Pole. This phenomenon, which only occurred in 1997 and 2011, has also produced this time the largest hole ever observed above the North Pole, announced Tuesday the Royal Belgian Meteorological Institute (RMI).
The presence of the hole in the ozone layer above the South Pole is an annual phenomenon, starting in August and disappearing in November. However, the presence of such a hole above the North Pole is on the other hand quite rare, since it seems to occur only approximately once per decade (the previous ones date back to 1997 and 2011).
While the hole observed in 2019 above the South Pole had been one of the smallest in 30 years, the hole that formed above the North Pole seems to be the widest of the three ever observed. "Although these two phenomena are not linked, they develop via the same process", explained the IRM relayed by the Belga press agency.
Holes in the ozone layer are caused by chlorofluorocarbons, or CFCs, emitted into the atmosphere for decades through the use of aerosols, refrigerants, pesticides and other solvents, now prohibited by the Montreal Protocol, adopted in 1987.
Exceptionally strong vortex
These CFCs have reached the stratosphere, a layer of the atmosphere, which extends between 10 and 50 km above the Earth's surface. But these gases have a very long lifespan (more than 100 years for some) and continue to affect the ozone layer, our "sun protection", which retains most of the solar UV radiation, dangerous for humans.
For the time being, the temperatures observed above the North Pole, at an altitude of around 20 km, are reaching record minimum values and the polar vortex is exceptionally strong.
With very low temperatures, CFCs form, with the rare traces of water present in the stratosphere (in the form of ice or vapor), pearly clouds, explains the IRM. When sunlight reaches these clouds, the CFCs present break the ozone molecules very actively.
Currently, “although the spring light of the Sun is back over the North Pole, pearly clouds are still observed at the level of the polar vortex. This exceptional situation causes the presence of a hole in the ozone layer, ”continues the MRI.
In the coming weeks, the sunlight will warm the stratosphere above the North Pole, which will make the pearly clouds disappear and leave the hole in the ozone layer to disappear by itself.
Related links:
Royal Belgian Meteorological Institute (RMI): https://www.meteo.be/en/belgium
Air: https://www.nasa.gov/subject/3126/air
Climate: https://www.nasa.gov/subject/3127/climate
Earth: https://www.nasa.gov/topics/earth/index.html
Goddard Space Flight Center (GSFC): https://www.nasa.gov/centers/goddard/home/index.html
Images, Video, Text, Credits: NASA/Goddard Space Flight Center Scientific Visualization Studio - Licence : CC BY-NC/AFP/Orbiter.ch Aerospace/Roland Berga.
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