The Decreasing Influence of Carbon Dioxide

On 8 March, 2010, David Archibald wrote a guest post on WUWT entitled “The Logarithmic Effect of Carbon Dioxide”. This was brought to my attention recently as an article worthy of attention, so here it is.

The greenhouse gases keep the Earth 30° C warmer than it would otherwise be without them in the atmosphere, so instead of the average surface temperature being -15° C, it is 15° C. Carbon dioxide contributes 10% of the effect so that is 3° C. The pre-industrial level of carbon dioxide in the atmosphere was 280 ppm. So roughly, if the heating effect was a linear relationship, each 100 ppm contributes 1° C. With the atmospheric concentration rising by 2 ppm annually, it would go up by 100 ppm every 50 years and we would all fry as per the IPCC predictions.

But the relationship isn’t linear, it is logarithmic. In 2006, Willis Eschenbach posted this graph on Climate Audit showing the logarithmic heating effect of carbon dioxide relative to atmospheric concentration:

modtrans graph

And this graphic of his shows carbon dioxide’s contribution to the whole greenhouse effect:
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