Jim Manzi has a very good post introducing the analysis of costs and benefits of Waxman-Markey. Here I want to follow up on Manzi’s great start, by showing that Chip Knappenberger’s estimate of the climate benefits of Waxman-Markey (W-M) actually erred on the side of optimism in its assumptions.

Specifically, Knappenberger very conservatively ignored the problem of “leakage”–he didn’t model the fact that unilateral U.S. carbon caps would actually increase the rate at which other countries’ own emissions grow. What’s worse, even if the entire world signed on to the aggressive emission schedule in W-M, the resulting environmental benefits would be achieved at a staggering cost in terms of lost economic output.

No matter how you slice it–whether the U.S. goes it alone, or the rest of the world signs on too–the environmental benefits of W-M are swamped by its economic costs.…

[Editor Note: This is a response to the commons analogy of Gavin Schmidt at RealClimate to Mr. Knappenberger’s temperature analysis of Waxman-Markey]

“Hear ye, hear ye, the Emperor is parading by with his new wardrobe of ideas to save the world from global warming—a wardrobe painstakingly crafted for him by the tailor shop of Waxman-Markey—and which all of you will soon have to adopt. All hail the Emperor!”

“But he has nothing on!” cried a small, but persistent voice. “His expensive ideas do nothing to change the climate!”

“Hush, little boy.” “Quiet!” “Shhhh.” “Shut up!” “That kid doesn’t see the whole picture!”

“The whole picture?” the little voice persisted.…

President Obama and his administration take pains to stress that their climate and environmental policies will be informed by the best science available. And that is as it should be, but the entire task can be complicated by the fact that sometimes the best available science may not be good enough for the task at hand.

Anthony Watts’s report on the Surfacestations project—Is the U.S.…

“Binding emissions targets for the developing nations are out of the question.”

– Eileen Claussen, Pew Center on Global Climate Change, March 2009

As I demonstrated in my analyses last week (here and here), the impact on global temperatures of U.S. actions to reduce greenhouse gas emissions pursuant to the Waxman-Markey climate bill (which called for a whopping 83% reduction by 2050) was close to nil. Or more precisely, about 0.05°C (0.09°F) by the year 2050, expanding to maybe 0.1°C–0.2°C by the end of the century, depending on, among other things, which future emissions course is assumed as the baseline.

And as the negotiations continue into the specific details of the proposed legislation, the emission reduction schedule has begun to slip—and so too does the potential climate impact.

So what is the temperature impact of a dirty Waxman-Markey bill versus the “clean” bill’s 0.05°C/0.09°F?…