2020 Weather Patterns Push Antarctic Ozone Hole to 12th Largest on Record

Narration: Kathleen Gaeta

Transcript:

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On September 20, the Antarctic

ozone hole reached an extent of

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24 point 8 million square

kilometers. 2020 was the 12th

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largest hole on record in 2019.

The peak extent was the second

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smallest hole on record, but

this stark contrast doesn't mean

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the hole is worsening. That's

where weather patterns come in.

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Colder temperatures are one of

the factors that activate ozone

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depletion, which means that

weather patterns play a vital

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role in determining the ozone

holes extent each year. The

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Antarctic ozone hole peaks

during the southern hemisphere's

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late winter, when temperatures

are at a low and the sun's rays

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return. The 2020 ozone hole was

exceptionally large due to a

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stable and cold Antarctic

vortex, the stratospheric low

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pressure system that flows

clockwise in the atmosphere

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above Antarctica. It's there

that the colder conditions help

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support formation of polar

stratospheric clouds, whose

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cloud particles activate ozone

layer destroying forms of

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chlorine and bromine compounds.

These compounds stem from

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years of human production and

used to be found in things like

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aerosol sprays and refrigerants.

Unfortunately, it took years to

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realize how damaging they are to

the ozone.

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If chemically active forms of

chlorine and bromine are

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present, and there are both cold

enough temperatures and sun

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rays, a reaction occurs on the

surfaces of cloud particles that

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form in cold stratospheric

layers, leading ultimately to

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runaway reactions that destroy

ozone molecules. The Antarctic

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ozone hole was first discovered

by researchers at the British

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Antarctic Survey in 1985. Just a

few years later, in 1987, the

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international community signed

the Montreal Protocol on

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substances that deplete the

ozone layer. Countries as small

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as the Vatican and as far as

North Korea signed the deal,

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regulating the consumption and

production of ozone depleting

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compounds. Since 2000, human

made ozone depleting substances

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have slowly declined, but remain

high enough to produce

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significant ozone loss. These

compounds have lifetimes of more

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than 50 years, which is why

we're still seeing their effects

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on the environment today. The

ozone hole over Antarctica is

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expected to gradually become

less severe, as

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chlorofluorocarbons continue to

decline. And because of

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scientifically supported

international action. Scientists

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expect the Antarctic ozone to

recover back to 1980 levels

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around the year 2070.