My thanks to Ed Hoskins, who would like a talkshop discussion concerning his analysis of the diminishing effect of increasing carbon dioxide in the atmosphere. His article tries to show that even if CO2 has the warming power the IPCC attributes to it, most of it’s ability to cause warming is already in lay, and that adding more will have little effect. Although this study doesn’t take any account of warming allegedly ‘in the pipeline’, recent assessments by Tim Channon and Roger Andrews indicate the e-folding time of CO2 is considerably less than IPCC estimates.
The influence of Carbon Dioxide CO2 on temperature
Ed Hoskins – Oct 10 2013
The temperature increasing capacity of atmospheric CO2 is known to diminish as concentrations increase. This diminution effect is probably the reason why there was no runaway greenhouse warming caused by CO2 in earlier eons when CO2 levels were known to be at levels of several thousands ppmv.
Both sceptics and Global Warming advocates agree on this. IPCC Published reports, (TAR3), acknowledge that the effective temperature increase caused by growing concentrations of CO2 in the atmosphere radically diminishes with increasing concentrations. This information has been in the IPCC reports. It is well disguised for any lay reader, (Chapter 6. Radiative Forcing of Climate Change: section 6.3.4 Total Well-Mixed Greenhouse Gas Forcing Estimate)[i].
Up to 200 ppmv, the equivalent to about 82% of the temperature increasing effectiveness of CO2, is essential to maintain plant life and thus life on earth. The current level of ~400 ppmv is already committed and immutable. At that level it amounts to 93% of the warming effect of CO2 in the atmosphere .
Thus only about 7% of the effectiveness of CO2 as a warming greenhouse gas now remains.