science | ambiance
The area of low concentration of this UV-protective gas is 23.2 million square kilometres, much less than in 2006
This year’s so-called ‘ozone hole’ was shrunk to 23.2 million square kilometers – the Iberian Peninsula has an area of 583,000 square kilometers – between September 7 and October 13, NASA and the US Oceanic and Atmospheric Administration (NOAA) said. The Antarctic region of low ozone concentration was the last Australian spring, when the “hole” recorded its annual maximum, which is slightly smaller than in 2021 – when it reached 23.3 million square kilometers – and was “well below the average observed In 2006, when the size of the “hole” peaked.
Ozone (O3) is a gas found mainly (90%) in the stratosphere, at an altitude of 10 to 50 km. It acts as a natural shield against harmful UV rays that cause skin cancer and cataracts. In the mid-1970s, scientists discovered alarming depletion of the ozone layer over Antarctica due to the destruction of this gas by chlorofluorocarbons (CFCs) used in refrigerators and air conditioning systems. In 1987, 197 countries signed the so-called Montreal Protocol to Eliminate CFCs, which has since led to the gradual recovery of Antarctic ozone. According to scientists’ predictions, the layer of this gas over the South Pole could fully recover by 2050.
“Over time, steady progress is being made and the hole is shrinking,” Paul Newman, chief Earth science scientist at NASA’s Goddard Space Flight Center, said of the latest data. “We’re seeing some fluctuations as weather and other factors cause the numbers to vary a little from day to day and week to week. But, overall, (the ‘hole in the ozone layer’) has shrunk in the past two decades,” emphasizes this expert.
Photographic sequence of the ascent of a sounding balloon from the Amundsen-Scott Column Ozone Base over Antarctica. /
NASA and NOAA scientists monitor the “ozone hole” with instruments aboard the Aura, Suomi NPP and NOAA-20 satellites. On October 5th, those satellites spotted a one-day “ozone hole” with a maximum of 26.4 million square kilometres, slightly larger than last year.
In addition, NOAA scientists working at the Amundsen-Scott South Pole Station, located in the geographic South Pole, are also recording the thickness of the ozone layer by launching balloons carrying instruments that measure the total amount of ozone between the Earth’s surface and the edge of space as they ascend. The world average column ozone is about 300 Dobson units. On October 3, NOAA scientists recorded a minimum value of ozone over Antarctica of 101 Dobson units. NASA explains that at that time, ozone was almost completely absent at altitudes between 14 and 21 kilometers, a pattern very similar to last year.
Some scientists were concerned about the possible impact of the underwater eruption of the Honga Tonga-Hunga Hapai (Tonga) volcano, which in January caused a tsunami that hit the Tonga islands and a tidal wave in Fiji. They feared something similar would happen to 1991, when the Pinatubo eruption in the Philippines released huge amounts of sulfur dioxide that affected the ozone layer. This year, however, no direct effects from the eruption of the Tonga volcano on Antarctica have been detected.
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