Gernot Wagner and Marty Weitzman argue strongly in today's New York Times (here) that the risks of extreme increases in global mean temperatures swamps any uncertainties that climate change might not turn out to be as much of a problem as scientists currently believe. They calculate a 5 to 10 percent chance that global mean temperature could increase by 6 degrees Celsius or more over a relatively short period of time, entailing socio-economic consequences "outside anyone's imagination, perhaps even Dante's." Therefore, in their view, lingering uncertainties about climate change effects should cut in favor of "an even more sharply decreasing path" in anthropogenic greenhouse gas emissions.
What makes this op-ed so compelling is that Weitzman (I don't know Wagner's work so well) is no alarmist or doomsayer, but an extremely rigorous and respected mainstream economist (very likely a future Nobel Prize winner for his ground-breaking work in environmental economics). Policy-makers should (but probably won't) pay very close attention to what he writes.