Int. J. Environ. Res. Public Health 2011, 8 1024 alternatives to achieving the same benefits leads to substantially different economic conclusions than most previous economic analyses, including the following:  Athough there are significant uncertainties with regard to exactly what assumptions other economic analyses have made, a good case can be made that the economic benefits of reducing CO2 emissions may be about two orders of magnitude less than those previously estimated by most economists because the climate sensitivity factor (CSF) is much lower than assumed by the United Nations because feedback is negative rather than positive and the effects of CO2 emissions reductions on atmospheric CO2 are short rather than long lasting.  The costs of CO2 emissions reductions are very much higher than usually estimated because of technological and implementation problems recently identified. Attempts to decrease these costs by a greatly expanded government funded research program to encourage technological innovation are both expensive and may or may not prove successful in reducing the technological problems.  Geoengineering such as solar radiation management is a controversial alternative to CO2 emissions reductions that offers opportunities to greatly decrease these large costs, change global temperatures with far greater assurance of success, and eliminate the possibility of low probability, high consequence risks of rising temperatures, but has been largely ignored by economists. The costs of this promising but so far not carefully researched and validated approach appear to be many orders of magnitude cheaper, albeit with possible new and also little researched risks. It would, however, introduce the possibility of unforeseen new risks, but these risks could be reduced with relatively low cost research if carried out before any implementation. With such a modest research program a geoengineering option could provide an insurance policy against CAGW if that should ever become a realistic possibility. This approach should remove concern about low probability, high consequence events arising from increasing global temperatures since such SRM could be implemented extremely rapidly with adequate preparations, unlike (probably futile) attempts to reduce atmospheric CO2 levels decades in advance, as currently proposed by the UN and many Western governments. So there is no basis for taking any action currently to control climate change, but research on the implementation of geoengineering options such as SRM might be worthwhile. 6.2. More General Conclusions with Respect to Carrying Out Economic Analyses of Environmental Mitigation Although it is not always necessary for environmental economists to understand the physical science aspects of the proposed environmental control measures proposed and to determine whether there may be lower cost means to achieve the benefits desired from the proposed mitigation, it certainly never does any harm and in most cases involving multidisciplinary issues it is vital if economists are to provide realistic and useful advice to decision makers. Some may object that in this specialized world economists should leave such matters to physical scientists since it is believed that they will know more about them. The danger, of course, is that economists may place their trust in