The effectiveness of CO2 as a greenhouse gas becomes ever more marginal with greater concentration

Interesting read, if I understand it correctly!

Watts Up With That?

The political target of limiting the effect of Man-made global warming to only +2⁰C can never be attained.

Guest essay by Ed Hoskins

According to well understood physical parameters, the effectiveness of CO2 as a greenhouse gas diminishes logarithmically with increasing concentration and from the current level of ~390 ppmv, (parts per million by volume). Accordingly only ~5% of the effectiveness of CO2 as a greenhouse gas remains beyond the current level.

This inconvenient fact is well understood in the climate science community. It can be accurately modeled using the Modtran program maintained and supported at the University of Chicago.

The logarithmic diminution of the effect of CO2 is probably the reason why there was no runaway greenhouse warming from CO2 in earlier eons when CO2 levels were known to be at levels of several thousands ppmv.

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