Hole in the ozone layer that develops annually is 'rather larger than usual' this year - and is currently bigger than Antarctica, scientists say
The annual hole in the Earth's protective ozone layer that appears over the Southern Hemisphere is 'rather larger than usual' — and is currently bigger than Antarctica.
Acting like a shield, ozone absorbs UV light from the sun. Its absence means more of this high-energy radiation reaches the Earth, where it can harm living cells.
The ozone layer is depleted by chemical reactions, driven by solar energy, that involve the by-products of human-made chemicals that linger in the atmosphere.
Each year, this causes a hole to form over the south pole between August and October — the southern hemisphere summer — peaking at the start of October.
The size of the hole is strongly dependant on weather conditions. Cold conditions last year saw one of the largest on record, while 2019's was the smallest.
Following an average start this year, the hole has grown considerably in the last week, the European Union's Copernicus Atmosphere Monitoring Service said.
As of yesterday, the hole covered an area of around 8.8 million square miles (23 million square km).
In years with normal weather conditions, the hole typically grows to a maximum area of about 8 million square miles (20.7 million square kilometres).
Despite these natural fluctuations, experts expect the hole to close permanently by 2050, in response to restrictions on ozone-depleting chemicals introduced in 1987.
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The annual hole in the Earth's protective ozone layer that appears over the Southern Hemisphere is 'rather larger than usual' — and is currently bigger than Antarctica. Pictured: a map of the ozone hole over Antarctica as seen on September 16, 2020
The size of the ozone hole is strongly dependant on weather conditions. Cold conditions last year (blue) saw one of the largest on record, while 2019's (green) was the smallest. This year's dimensions are depicted above in red
'We are looking at a quite big and potentially also deep ozone hole.'
According to Dr Peuch, the ozone hole that was observed last year also started out unremarkably, but proceeded to turn into one of the longest-lasting manifestations of the phenomenon on record.
In fact, measurements from the Copernicus Sentinel-5P satellite revealed that last year's hole was also one of the largest and deepest of recent years, reaching around 9.7 million square miles (25 million square kilometres) in total area.
According to the European Space Agency, last year's hole was driven by a 'strong, stable and cold polar vortex' which consistently lowered the temperature of the ozone layer over Antarctica.
The evolution of this year's ozone hole appears to be progressing along a similar track, with it presently being larger for this time of the season than 75 per cent of holes since 1979.
'This ozone evolution is what we would expect given the current atmospheric conditions,' said European Centre for Medium-Range Weather Forecasts senior scientist Antje Inness.
'The progress of the ozone hole over the coming weeks will be extremely interesting.'
This year, Dr Peuch added, 'the vortex is quite stable and the stratospheric temperatures are even lower than last year — so [the ozone hole] may continue to grow slightly over the next two or three weeks.'
Measurements from the Copernicus Sentinel-5P satellite (depicted) revealed that last year's hole was one of the largest of recent years — reaching around 9.7 million square miles in area
'The monitoring of the ozone hole over the South Pole must be interpreted carefully as the size, duration and the ozone concentrations of a single hole are influenced by the local wind fields, or meteorology, around the South Pole.
'Nevertheless, we expect a closing of the ozone hole over the South Pole by the year 2050.'
The depletion of the ozone layer was first detected by scientists in the 1970s, and was determined to be greater than could be accounted for by natural factors like temperature, weather and volcanic eruptions.
Instead, it was determined that human-made chemicals — in particular halocarbons refrigerants and chlorofluorocarbons (CFCs) — were exacerbating the depletion.
In 1987, these manufacture and consumption of these products began to be phased out under an international treaty known as the Montreal Protocol.
However, the fact that many ozone-depleting substances can stay up in the stratosphere for decades means the ozone layer's recovery is very slow process.
In fact, experts have predicted that it will take until the 2060s before the harmful substances used in refrigerants and spray cans have completely disappeared from the atmosphere.
Acting like a shield, ozone absorbs UV light from the sun. Its absence means more of this high-energy radiation reaches the Earth, where it can harm living cells. The ozone layer is depleted by chemical reactions, driven by solar energy, that involve the by-products of human-made chemicals that linger in the atmosphere. Pictured: ozone levels vary with altitude
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