david v goliath campaign, page-18

Good post. TU

You may be interested in this from Richard Lindzen

The greenhouse effect of carbon dioxide increases is logarithmic. It is not linear. Richard Lindzen, a climate scientist who is a professor of meteorology at MIT, has explained:

"In terms of climate forcing, greenhouse gases added to the atmosphere through man’s activities since the late nineteenth century have already produced three-quarters of the radiative forcing that we expect from a doubling of CO2 … the impact of CO2 is nonlinear in the sense that each added unit contributes less than its predecessor. For example, if doubling CO2 from its value in the late nineteenth century—from about 290 parts per million by volume (ppmv) to 580 ppmv—causes a 2 per cent increase in radiative forcing, then to obtain another 2 percent increase in radiative forcing we must increase CO2 by an additional 580 ppmv rather than by another 290 ppmv. At present, the concentration of CO2 is about 380 ppmv. The easiest way to understand this is to consider adding thin layers of paint to a pane of glass. The first layer cuts out much of the light, the next layer cuts out more, but subsequent layers do less and less because the painted pane is already essentially opaque."

Lindzen’s “already produced” radiative forcing should not be confused with the effect of this forcing on global average temperatures, which may take decades or centuries to respond, because of the thermal inertia of the oceans. His conclusion is that if we believe the climate models, “we have long since passed the point where mitigation is a viable strategy”. His estimate of the future outcome is: “Attempts to assess climate sensitivity by direct observation of cloud processes, and other means, point to a conclusion that doubling of CO2 would lead to about 0.5 degrees warming or less.”

http://quadrant.org.au/magazine/2011/03/the-intelligent-voter-s-guide-to-global-warming/