Emeritus Professor Geoff Duffy writes: "The GHG concentration of the actual atmosphere is 1.028% of the total atmosphere, based on water vapour being 1% (200C, 75% Relative Humidity). The main gases from possible agricultural sources (methane and nitrous oxide) total only 0.02% of all the GHG, or 0.00021% of the total atmosphere......Hence, it can be concluded from all the available evidence that their contribution to any potential change in weather is miniscule".