Human element of CO2 is 'tiny'
Carbon dioxide is not one part in every five million of the atmosphere but about 300 parts. The human contribution to CO2 is about 3pc so that makes the total nine parts in a million. However, Michael Job (Letters, March 10) is wrong to say that only CO2 has a greenhouse effect (by which he means only it absorbs infrared light).
Oxygen and nitrogen, which make up more than 99pc of the atmosphere, do absorb infrared, albeit not as strongly but there is so much more of it.
A greater greenhouse gas, both in its quantity in the atmosphere and its absorptive powers, is water vapour.