[David and Judith Coley]

David and Judith Coley  asked the Naked Scientists:
   
Dear Chris
 
Regarding the ozone layer, or more precisely the hole in it caused by global warming, I heard that the now-banned CFCs, under certain temerature conditions, can cause up to 10,000 times more damage than the same amount of CO2. Is this correct and why is this please?
  
Very Curious      
 
 
Dave Coley

What do you think?

[SkepticSam]

The hole in the ozone layer and global warming need to be separated. Ozone in the stratosphere is essential to life on the planet and protects us from UV radiation. Tropospheric ozone is both harmful to health and a greenhouse gas .

Global warming is a warming of the troposphere and the ozone hole forms in the stratosphere. The confusion arises because cfc's play a part and contribute to both.

Basically chloroflurocarbons (cfc's) absorb the outgoing IR radiation and effectively act as a heat trap close to the surface adding to global warming. Yet stratospheric cfc's are broken down by UV radiation into chlorine radicals. It's these radicals that destroy the ozone.

To further complicate matters the hole in the ozone layer changes the earths radiation budget and actually (slightly) cools the earth.

As for the other part of your question. I'm sure a friendly chemist will be able to offer an answer.

[chris]

CO2, indirectly via global warming, can also affect ozone since it can retard the rate of stratospheric ozone production, I believe?

Chris

[Bored chemist]

Like CO2 the CFCs are potent greenhouse gases. They contribute towards global warming (OK some members of the flat earth society and the oil copanies say they don't).

However the damage to the ozone layer is due to a different effect. The CFCs are farily unreactive, once released into the atmosphere they drift up to the stratosphere. When they get there they are decomposed by the hard UV radiation and produce a bunch of odd chemicals like chlorine.
The chlorine (etc.) catalyses the destruction of ozone.