This ozone layer hole that was once larger than Antarctica has finally closed.

The ozone is a layer in the Earth’s stratosphere that serves as a protective sheet against most of the ultraviolet (UV) radiation from the sun. For decades, human activities have been depleting the ozone, from greenhouse gas to carbon emission to who knows what else. Later last year, scientists from the Copernicus Atmosphere Monitoring Service (CAMS) made an announcement that was worthy for a celebration. Fortunately, the largest-ever ozone layer hole has finally closed.

Once Upon A Hole

The ozone hole, known as the 2021 Antarctic Ozone Hole, was once larger than (you guessed it) Antarctica, and had reached its maximum size on October 7, 2021. This was the 13th largest hole on record since 1979 — one year after the Montreal Protocol was signed. It closed later than 95 percent of all ozone holes that has been tracked ever since.

The Montreal Protocol was an agreement signed by 197 countries in 1979 which aimed at protecting the environment. The agreement set forth regulations on the production and use of dozens of substances that were deemed as ozone-depleting substances.

This helped placed bans on damaging chemicals, particularly chlorofluorocarbons (CFCs). These were gases that were highly used in aerosol diffusers and refrigerators before the 1960s and 70s. Later on, scientists discovered that CFCs pose a threat to the thinning region of ozone over Antarctica.

The ozone layer hole as seen over Antarctica by NASA Earth Observatory
Image: NASA Ozone Watch | The ozone layer hole as seen over Antarctica by NASA Earth Observatory

The Largest Ozone Hole

The thinning of the ozone allows more UV rays from the sun to reach the Earth’s surface, which can be a threat to not only humans, but to the biosphere. According to the United Nations, the Montreal Protocol has prevented millions of additional cases of melanoma — a rare form of skin cancer — other cancers, and even eye cataracts.

Scientists estimate that the ozone layer is more likely to recover by the mid-century, but many more areas in the ozone are still thinning, and some holes seem not to close. However, others claim that certain conditions and patterns within the atmosphere contributes to some thinning regions and holes. One of such is the one that recently closed over Antarctica.

The National Aeronautics and Space Administration (NASA) stated that the 2021 Antarctic ozone hole was “substantially smaller” than the ones recorded in the late 1990s and early 2000s.

Image: Copernicus Atmosphere Monitoring Service / ECMWF

“This was a large ozone hole because of the colder than average 2021 stratospheric conditions, and without a Montreal Protocol, it would have been much larger,” stated Paul Newman, the chief scientist for Earth sciences at NASA’s Goddard Space Flight Center, in an article published by NASA.

End Of The Whole Zone

The hole emerges each year over Antarctica between August and October; and in September of 2021, it was larger than the continent itself. It is the second longest-lasting hole in over 40 years to close. The Southern Hemisphere experienced an abnormally cold winter.

Antarctica reached a record-breaking temperature with an average of -60.9 degrees Celsius (-77.6 degrees Fahrenheit), from August through September. There were strong persistent winds that led to the widening of the ozone hole.

“If atmospheric chlorine levels from CFCs were as high today as they were in the early 2000s, this year’s ozone hole would have been larger by about 1.5 million square miles (about four million square kilometres) under the same weather conditions,” NASA stated.

Source: NASA / Copernicus Atmosphere Monitoring Service

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Written by: Nana Kwadwo, Fri, Jan 14, 2022.


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