Int. J. Environ. Res. Public Health 2011, 8 1021 Figure 8. HadCRUT3 and UAH versus IPCC model global surface warming. Source: [80], based on a graph prepared by Dr. John Christy. In other words, Krugman argues that because he has heard that there could be CAGW effects, it is worth disregarding the ―standard‖ ramp-up approach advocated by many economists who have studied the question and spending very large amounts immediately on climate change mitigation to avoid this low probability possibility because they could be catastrophic. This approach assumes, of course, that what he has heard as to CAGW effects is of sufficient reliability to justify such early and overwhelming expenditures without careful analysis. As discussed in Section 2.6.2, however, application of the scientific method shows that the CSF is much less than assumed by the IPCC and may be in the range of 0.6 to 0.7 °C. This implies that CAGW effects are no more of a possibility now than they have been during the current Holocene period to date. But given the strong scientific case made in Section 2.3.1 above for low rather than high sensitivity, the scientific case for such outcomes disappears, and we are left with conventional benefit-cost analysis as a basis for making an economic decision. Presumably given his earlier comments his views that CAGW effects are a realistic possibility are based on the global climate models used by the IPCC. So without examining the extent to which these climate models represent an accurate representation of the climate system, he appears to be proposing that very large amounts be spent starting immediately because of the output from these models. This appears to be a triumph of climate scare fears over careful physical science and economic analysis. As discussed in Section 3 above, however, there exists an alternative approach to mitigation which would cost only a small fraction of the GHG emissions control approach, has a realistic possibility of actually controlling global climate change, and does not need to be implemented until actual CAGW