The year 2020 began with a wave of fires in Australia, the boreal 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 the apocalyptic scenario, a few days ago NASA satellites reported a huge hole in the Arctic ozone layer.
Although it does not threaten human health and, if the predictions are fulfilled, it will disappear in a short time, it is undoubtedly an extraordinary atmospheric phenomenon that will swell the record books. Why has it occurred?
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 high-altitude clouds to collect above the South Pole. At that 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 part of that ozone. When temperatures rise, ozone recovers. This hole in the ozone layer in Antarctica is well studied, and usually reaches its maximum size each year between August and November.
Why is this phenomenon not so common at the North Pole? The Arctic area has much more variable temperatures than the South Pole, and temperatures are not so low. Towards the end of February and 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 in this area , a phenomenon that, together with the formation of a polar vortex – a region of low pressures that keeps cold air confined – has produced especially strong the formation high-altitude clouds and triggering ozone destruction.
Similar phenomena of ozone layer thinning had already been recorded in 1997 and 2011, but what was observed in 2020 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 towards more populated areas, in which case it would be necessary to take extra protection measures against solar radiation”, explains Markus Rex, an atmospheric scientist at the Alfred Wegener Institute (Potsdam , Germany) in an interview with Nature .
However, and since the temperatures of the North Pole have already begun to rise, it is expected that the polar vortex will separate in the coming weeks, which will be crucial to fully understand the evolution of this unusual phenomenon.
Things would be worse if no action had been taken
In 1987 there 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 destruction. ozone, paying special 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 we must take into account the chemicals that were restricted in the agreement will still take decades to completely disappear from the atmosphere,” concludes the scientist.
