The Ozone Layer
What is it?
What caused
the hole in
the Ozone
layer?
Is it closing
up?
The Ozone layer is an invisible
layer surrounding the Earth’s
atmosphere which is made out of
gases, mostly very high
concentrations of ozone. It is
between 10km and 50 km above
the Earth. The ozone layer
absorbs 93-99% of the sun’s high
frequency ultra violet light, which
is damaging to life on earth if too
much filters through the
atmosphere. UV-B radiation
causes skin cancer and
suppresses immune systems. It
can also damage wildlife and
plants. This diagram shows how
the Ozone layer protects the earth from harmful UV rays.
Over the past 60 years or so, humans have contributed to the deterioration of the
ozone layer. Poisonous gases such as chloro-fluoro-carbons (CFCs) pollute the
atmosphere as a result of human activity. They build up over the Antarctic and break
down the ozone layer leading to a hole being created. The hole was increasing in size
up until 1990 and was up to 27 million sq km.
There are some reports in the media suggesting that the ozone layer is reducing in
size. Data shows a decrease since 1994, and UV amounts are down 6% since the
height of the problem. Satellites show that the rate in which the ozone layer is
closing is slowing down. There is a delay between data on the Earth’s surface and
what is happening on the ozone layer by a few years, so it will be at least a decade
before we are sure that the hole is closing up. However CFC emissions have been
reduced since it was agreed their usage would be cut in 1987.
The hole in the ozone layer is often confused with global warming - they are
separate issues. The main link is that the gas which breaks down ozone
(CFCs) is also a greenhouse gas, which causes heat to be trapped around
the Earth, leading to global warming.
Date
printed
26/08/11
www.northfieldecocentre.org 0121 448 0119 [email protected]
The Central England Area Quaker Meeting Charities
Registered Charity Number 224571
Version 1.0
F5-04
June 2011