While we understand the evidence that has led them to view CO2 emissions as harmful, the IPCC's conclusions are quite inadequate as justification for implementing policies that will markedly diminish future prosperity. In particular, it is not established that it is possible to significantly alter global climate through cuts in human greenhouse gas emissions. On top of which, because attempts to cut emissions will slow development, the current UN approach of CO2 reduction is likely to increase human suffering from future climate change rather than to decrease it.
The crux of the matter, future prosperity. The question should be, For who.