Generation Steve and I had an interesting discussion on Global Warming today following his inexplicable decision to drop hard earned money on An Inconvenient Truth over the weekend. So, in honor of him, I present some basic facts and figures regarding greenhouse gases, carbon dioxide emissions, and consensus.
Or, there is the abridged version:
The guesses of significantly larger warming are dependent on "feedback" (supplementary) mechanisms programmed into climate models. The existence of these "feedback" mechanisms is uncertain and the cumulative sign of which is unknown (they may add to warming from increased atmospheric carbon dioxide or, equally likely, might suppress it).
The total warming since measurements have been attempted is thought to be about 0.6 degrees Centigrade. At least half of the estimated temperature increment occurred before 1950, prior to significant change in atmospheric carbon dioxide levels.
There is no linear relationship between atmospheric carbon dioxide change and global mean temperature or global mean temperature trend -- global mean temperature has both risen and fallen during the period atmospheric carbon dioxide has been rising.
The natural world has tolerated greater than one-degree fluctuations in mean temperature during the relatively recent past and thus current changes are within the range of natural variation.
Despite attempts to label atmospheric carbon dioxide a "pollutant" it is, in fact, an essential trace gas, the increasing abundance of which is a bonus for the bulk of the biosphere.
There is no reason to believe that slightly lower temperatures are somehow preferable to slightly higher temperatures - there is no known "optimal" nor any known means of knowingly and predictably adjusting some sort of planetary thermostat.
Fluctuations in atmospheric carbon dioxide are of little relevance in the short to medium term (although should levels fall too low it could prove problematic in the longer-term).
I think it might be a long uphill battle, but ultimately GS is a smart guy and will recognize the fallacy of Global Warming. He just needs a little time....