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HOLE IN THE OZONE

STARTS TO HEAL

In 1987, virtually every nation in the

world signed the Montreal Protocol.

It was a concerted effort to ban the

use of CFCs in order to repair the

widening hole in Earth’s ozone

layer. Now, almost 30 years later, it

appears to have paid off as

scientists at MIT have found

evidence that the hole in the ozone

layer over the Antarctic is closing.

The team found that the ozone

hole has shrunk by more than four

million square km, or about half the

area of the United States, since

2000, when ozone depletion was at

its peak.

“We can now be confident that

the things we’ve done have put the

planet on a path to heal,” says lead

researcher Susan Solomon. “Which

is pretty good for us, isn’t it? Aren’t

we amazing humans, that we did

something that created a situation

that we decided collectively, as a

world, ‘Let’s get rid of these

molecules’? We got rid of them,

and now we’re seeing the planet

respond.”

The ozone hole was first

discovered in the 1950s. But

concerns began to grow in the mid-

1980s when scientists from the

British Antarctic Survey noticed it

was widening.

CFCs (chlorofluorocarbons),

chemical compounds once emitted

by dry-cleaning processes,

refrigerators, and aerosol sprays,

were thought to be the main culprit

because the chlorine they emit into

the atmosphere eats away at ozone.

According to Solomon, if levels of

chlorine in the atmosphere continue

to dissipate at the current rate, the

ozone hole could be closed by the

middle of the century.

Visualisation of the

changes in the hole

in the ozone layer

over Antarctica from

1979 to 2011, moving

from purple (low

ozone levels) through

to blue, green, yellow

and orange (high

ozone levels)

AGE

4.6 billion years

COMPOSITION
92.1% hydrogen, 7.8% helium,
0.1% oxygen, nitrogen, silicon and others

TIME UNTIL DEATH

5 billion years

ENVIRONMENT

International Space Station because when the
Earth’s atmosphere shrinks, these orbiting items
experience less drag and so their lifetimes increase.
Unfortunately, this is also the case for space debris!”
Sunspot activity is at its weakest since 1906,
which is a sign it could be heading to a long-term low
that could affect the climate.
“The Sun may be experiencing a longer term
decline in activity towards a Grand Minimum,” said
Haigh. “The last Grand Minimum occurred in the
late 17th Century and has been associated with a
cooler period in nor thwestern Europe referred to
as the Little Ice Age. 
“Our current understanding is that low solar
activity at that time had little impact on global
temperatures but may have resulted in regional
effects, including colder winters in northwestern
Europe. Looking ahead we might anticipate the
same effects.”