A hole in the ozone layer that develops annually from August to October over the South Pole has become larger than Antarctica this year, announced the Copernicus Atmospheric Monitoring Service Thursday.
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Antarctica is around 5.5 million square miles in size. The ozone layer is around nine to 18 miles above Earth’s surface.
According to the Environmental Protection Agency, the ozone is depleted when chlorine and bromine atoms come into contact with ozone in the stratosphere and destroy molecules.
“One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere,” said the EPA. “Ozone can be destroyed more quickly than it is naturally created.”
“When temperatures high up in the stratosphere start to rise in late Southern Hemisphere spring, ozone depletion slows, the polar vortex weakens and finally breaks down,” explained the Copernicus Atmosphere Monitoring Service. By December, the ozone in that area usually returns to normal.
However, Copernicus Atmosphere Monitoring Service Director Vincent-Henri Peuch said that last season’s Antarctic ozone hole was one of the longest lasting on record. Both last season’s hole and this season’s hole got off to a typical start, he added.
“Now our forecasts show that this year´s hole has evolved into a rather larger than usual one,” said Peuch. “The vortex is quite stable and the stratospheric temperatures are even lower than last year. We are looking at a quite big and potentially also deep ozone hole.”
Over the past week, the Antarctic hole has grown larger than 75 percent of ozone holes at that stage in the season since 1979, said the service.
To analyze how large tears in the Earth’s protective layer have become, the service uses computer modelling and satellite observations in a similar way to weather forecasts to provide a three-dimensional model. The service said five different sources are used to create a detailed picture.
According to the Copernicus service, Thursday marked the International Day for the Preservation of the Ozone Layer, which commemorates the Montreal Protocol’s ban of the main ozone depleting chemicals in 1987. A Nature article published this summer said the ozone layer may have been headed for collapse if the chemicals had not been banned.
“The ozone layer filters out harmful ultraviolet radiation, which is associated with an increased prevalence of skin cancer and cataracts, reduced agricultural productivity, and disruption of marine ecosystems,” explained the U.S.
Department of State’s description of the Montreal Protocol.
Since the ban on halocarbons, the ozone layer has shown signs of recovery, said the Copernicus Atmosphere Monitoring Service. Even so, the process is slow, and it may take until the 2060s or 2070s until there is a complete phasing out of ozone depleting substances.