Int. J. Environ. Res. Public Health 2011, 8 1013 Galiana and Green [57] also argue that most prior cost of mitigation analyses are grossly optimistic. Their arguments are summarized in the following excerpt: ―A ‗thought experiment‘ helps to illustrate. Suppose the emission reduction target is an 80% reduction in global emission from current levels by 2100. To reach the 2100 target requires a 1.8% average annual rate of decline in carbon emissions. Now suppose the expected ‗trend‘ rate of growth in global world output (GWP) from 2010–2050 is 2.2%. To avoid a reduction in the growth rate of GWP would require a 4.0% average annual rate of decline in the carbon intensity of output (RCIO)…. ―If a policy of reducing emissions by ―brute force‖ is adopted, irrespective of technical feasibility, even an increase in the average annual RCIO to 3.6% from its ‗historic‘ rate of 1.3% (a very unlikely event in the absence of a technology-led policy) implies a reduction in the growth rate of GWP from the 2.2% ‗trend‘ rate to 1.8% for the period 2010–2100. Such a reduction would cost (an undiscounted) $86 trillion in 2100 alone and an undiscounted $2280 trillion cumulative over the 90 year interval. (It is assumed GWP in 2010 is $41 trillion, measured in MER terms.) And even these huge reductions in GWP would not do the trick (meet the emission target) if we cannot push the rate of decline in C/GWP up to 3.6% (which is almost triple the ―historic‖ rate). ―The ‗thought experiment‘ casts serious doubt on the credibility of estimates of the cost of stabilizing climate. Estimates in the 1 to 3% of global GDP range—or lower (Stern, 2007; IPCC, 2007) are not credible unless there is a prior focus on reducing the technology gap. The low-cost estimates reflect a variety of self-serving assumptions. Some models employ an emission scenario baseline that builds in large, automatic improvements in energy technology. Other models include a carbon-free backstop technology (often generic) that assures that once the carbon price reaches a specified level there is an unlimited supply of carbon emission-free energy forthcoming. Still others have very high implicit rates of energy intensity decline, ones that would almost surely be physically impossible to achieve. Finally, some models make very optimistic assumptions (ones generally inconsistent with the evidence) about the availability and readiness of carbon-neutral technologies and/or the responsiveness of successful innovation of new energy technologies to carbon prices. ―None of these modeling conveniences or assumptions contribute to a reliable approach to estimating the cost of mitigation. Perhaps the most deceptive are models that build-in a backstop carbon-free energy technology, because this effectively assumes away what is the problem. Unless a specific effort is made to research and develop, test, and make ready-for deployment scalable carbon emission-free technologies, the cost of mitigation is likely to be as much as an order of magnitude, or more, higher than has been reported.‖ Galiana and Green‘s order of magnitude cost increase appears reasonable; I am much less optimistic, however, that a research and development effort such as they propose is likely to solve the problem of astronomical costs. The costs of CO2 emissions reductions on the scale proposed by CAGW supporters are very large and much higher than usually quoted. If ―conventional‖ mitigation is to be attempted (and I do not believe that it is economically justified or currently needed), some way