The year 2020 began with a wave of fires in Australia, this year’s winter has ended up breaking records of high temperatures and it is estimated that, currently, a third of humanity is confined due to the pandemic of the new coronavirus SARS-Cov-2. To finish off this apocalyptic scenario, a few days ago NASA satellites reported a huge hole in the Arctic ozone layer.
Although it doesn’t actually threaten humanity and, if the predictions are fulfilled, it will disappear in a short time, it is certainly an extraordinary atmospheric phenomenon that will add to the record books. Why is this happening?
The ozone hole at the South Pole
Ozone is a component of the stratosphere that forms a layer that protects living organisms from excess solar ultraviolet radiation. Every year, during the Antarctic winter, low temperatures cause many clouds to accumulate at high altitudes above the South Pole. During this time, chemicals such as chlorine and bromine, which come from various industrial sources, trigger a series of reactions on the surface of these clouds that result in the destruction of some of that ozone. When temperatures rise, the ozone recovers. This ozone hole in Antarctica is well studied, and usually reaches its maximum size every year between August and November.
Why is this phenomenon not so common in the North Pole? The Arctic area has increased variable temperatures than the South Pole, and temperatures are not as low. Towards the end of February and in March, when sunlight begins to reach the North Pole, its stratosphere is no longer cold enough to produce these clouds, essential for ozone destruction.
A particularly cold winter in the Arctic
This year, however, extremely low temperatures have been reached in the stratosphere of this area, a phenomenon that, coupled with the formation of a polar vortex - a region of low pressures that keeps cold air confined - particularly strong has produced cloud formation at high altitudes and triggered ozone destruction.
Similar thinning of the ozone layer had already occurred in 1997 and 2011, but what was observed in this year is on track to break all records. However, experts indicate that this hole does not pose a threat to human health. "In the coming weeks there is a small possibility that the hole will move to more populated areas, in which case extra protection against solar radiation would be necessary," explains Markus Rex, an atmospheric scientist at the Alfred Wegener Institute (Potsdam, Germany) in an interview with Nature.
However, since the temperatures of the North Pole have already begun to rise, the hope is that the polar vortex will break apart in the coming weeks, which will be crucial to fully understanding the evolution of this unusual phenomenon.
Things would be worse if no action had been taken
1987 was a milestone in the history of protecting the planet: the signing of the Montreal Protocol, an unprecedented international agreement through which the signatory countries undertook to take measures to control the use of substances that contribute to ozone destruction, with particular attention to chlorofluorocarbons (CFCs).
"The situation would be much worse if the 1987 Montreal Protocol had not been implemented," explains Paul Newman, an atmospheric scientist at NASA’s Goddard Space Flight Center, in the same interview with Nature. "The hole in the Antarctic ozone layer is clearly on the way to recovery, although it must take into account the chemicals that were restricted in the agreement will still take decades to completely disappear from the atmosphere," the scientist concludes.