Kind: captions
Language: en
remember the hole in the ozone layer a
piece of the sky has vanished why don't
we hear about it
[Music]
[Applause]
anymore in the 1980s scientists
discovered that part of the crucial
protective ozone layer in the Earth's
atmosphere was extremely thin
threatening to bring on a global crisis
from destroying plants and ecosystems to
Skyhigh skin cancer rates they also
discovered why the hole was forming and
why it was in the Antarctic when no one
really lives there but today the ozone
layer appears to be healing how the
ozone layer is about 9 to 18 M up a part
of the stratosphere that filters out
some harmful UV radiation from the Sun
UVC and most of UVB without it the sun's
Rays would absolutely Scorch life on
Earth especially damaging DNA ozone is a
gas made up of three atoms of oxygen
ozone at ground level where we can
breathe it in is a harmful pollutant
emitted by cars refineries and chemical
plants and can trigger health problems
but in the stratosphere ozone occurs
naturally and is good for life on Earth
in 1974 researchers started to realize
that chemicals called
chlorofluorocarbons or cfc's which were
found all over from refrigerators to
aerosol cans to air conditioners could
deplete ozone in the stratosphere but
what came next shocked the world
scientists had been measuring levels of
ozone in the Antarctic atmosphere for
decades in 1982 one researcher thought
his instrument was broken when he
measured dramatic drops in Ozone levels
but by 1985 scientists realized that
ozone levels in Antarctica had been
dropping consistently every spring since
the
1970s the area of thinning ozone known
as the ozone hole was massive but why
did the hole form over Antarctica a team
of scientists traveled to the continent
in the winter of 1986 and during brutal
temperatures and almost 24/7 Darkness to
study the ozone hole as it formed
seasonally over Antarctica they gathered
data that eventually established cfc's
as the major cause of ozone depletion
but why was the whole forming so far
from where most CFCs were being used
they discovered that it was the unique
meteorological and chemical conditions
in Antarctica that make ozone
destruction especially efficient there
it's so cold in the stratosphere during
Antarctic Winters that a specific kind
of cloud forms polar stratospheric
clouds that sets up the chemical
reactions that destroy ozone
ozone depletion happens elsewhere too
but not as much an international
agreement called the Montreal protocol
led to the global phasing out of cfc's
and it was effective the ozone hole has
been shrinking since 2006 but cfc's can
persist in the atmosphere for a long
time and human-caused and natural events
like volcanoes wildfires even rocket
launches have damaged the ozone layer
slowing progress still some research
suggest that without the agreement in
place Global temps could have risen by
an addition I de C or 1.8 de F today the
ozone layer is healing and expected to
return to a healthy level this century