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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 hemispheres

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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 and Arctic
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 stemmed 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, and reaction occurs on the
surfaces of cloud particles that

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form and 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 2017