One of the problems caused by greenhouse gasses is the hole in the ozone-layer. The
ozone-layer is our protection against Ultra Violet or UV radiation coming from the sun. UV
radiation is dangerous for our health because it can cause cancers and other mutations.
There are 3 types of molecules in the Stratosphere that block UV radiation as they
react with one another, there is the atomic Oxygen (O), the Oxygen gas (O2) and Ozone (O3).
An O2 molecule will absorb some UV radiation splitting into 2 O molecules, an O molecule
will absorb UV as it reacts with an O2 molecule to form O3 and finally and O3 will absorb UV
radiation either by reacting with an O molecule to form 2 O2 molecules or by splitting up into
an O2 and an O molecule.
There are however gasses that are more likely to react with Ozone. An example of
such a gas is Chlorine; it can react with an Ozone molecule to form ClO and an oxygen
atom, the ClO can in turn react with another O3 molecule to form Cl and 2 O2 now the Cl
molecule is as it were before the first reaction and the process starts over again, this
effectively reduces the Ozone in the stratosphere.
Another issue is the following: The ozone concentrations are the least above
Antarctica because the temperature is most favourable for the reactions of Ozone with
greenhouse gasses. Antarctica has a large plankton population. Despite the fact that
plankton breaks down greenhouse gasses, it is very vulnerable to UV radiation. As the
Ozone continues to disappear, so does the plankton, as the plankton disappears, more
greenhouse gasses make it into the stratosphere and more ozone can break down. This is a
continuous process that accelerates the reduction of Ozone.