The New Republic has posted some interesting pieces on the politics of climate change. Bill McKibben deplores the anti-science stance of the Republican party. Jim Manzi replies that McKibben and other climate-change activists have relied too much on stirring fear and exaggerating the costs of climate change–a strategy which, evidently, is no longer working.

This is the crux of problem with McKibben’s argument: According to the IPCC, the expected economic costs of global warming are about 3 percent of GDP more than 100 years from now. This is pretty far from the rhetoric of global devastation that McKibben, and so many others, use.

McKibben can use all the scare terms he wants, but this is not a prima facie case that we should want governments to reengineer the energy sector of the global economy coercively around the primary goal of lowering these projected future damages at the expense of, for example, more rapid worldwide economic growth.

Manzi is right about the disconnect between climate-activist rhetoric and the best estimates of what is at stake. The strongest argument for action is the the possibility of catastrophic outcomes much worse than the scenarios the IPCC and other modelers are discussing. Manzi dismisses this far too lightly. Attuning policy to this kind of small and unquantifiable danger is very difficult, but that is the challenge.

Michael Shellenberger and Ted Nordhaus take on the “green jobs myth”.

The Obama administration’s own analyses concluded that cap-and-trade would have resulted in net job loss, not job creation. That’s because the primary obstacle to building a clean-energy economy is not the absence of a carbon price, such as the one that would have been created by cap-and-trade. Rather, it is the vast price gap between fossil fuels and clean-energy technologies. While fossil fuels are energy dense, widely available, easy to consume, and supported by a well developed infrastructure, the alternatives are costly, cumbersome, intermittent, or all of the above.

Shellenberger and Nordhaus see little purpose in cap and trade, or other ways to raise the price of carbon. They want long-term public investment in green innovation instead. Must it be one or the other? These look like complementary approaches to me. Do both in moderation. The political challenge of bringing public opinion round has to be dealt with in either case.