In the lead essay for August’s Cato Unbound, Jim Manzi weighs various climate proposals and finds them wanting. He begins by putting the economic costs of global warming in perspective:

This is the central problem for advocates of rapid, aggressive emissions reductions. Despite the rhetoric, the best available estimate of the damage we face from unconstrained global warming is not “global destruction,” but is instead costs on the order of 3 percent of global GDP in a much wealthier world well over a hundred years from now.

It should not, therefore, be surprising that formal efforts to weigh the near-term costs of emissions abatement against the long-term benefits from avoided global warming show few net benefits, even in theory. According to the modeling group led by William Nordhaus, a Yale professor widely considered to be the world’s leading expert on this kind of assessment, an optimally designed and implemented global carbon tax would provide an expected net benefit of around $3 trillion, or about 0.2 percent of the present value of global GDP over the next several centuries. While not everything that matters can be measured by money, this certainly provides a different perspective than the “Earth in the balance” rhetoric would suggest.

This month’s issue should be a lively one, with responses on the way from Joseph Romm, Indur Goklany, and Michael Shellenberger and Ted Nordhaus. We hope you’ll find much to think about as the debate unfolds.