Manzi responds to Conor Clarke and counters Nate Silver. He responds to the Dish via e-mail:
You describe the implication of the back-and-forth as “small benefit / trivial cost”. Well, ~1% of the US economy is small as compared to the US economy, but huge as compared to just about anything else.
If we burned 1% of our GDP, that would be about $1.5 trillion in today’s dollars over a decade. Even if everything in W-M goes exactly according to plan, and the EPA’s numbers for cost are exactly right, and costs don’t rise beyond 2050, we are going to be losing that much national consumption every decade from 2050 through something like 2100 when we will start to get a tiny offset (as per my post, less than 1/10th of the costs each year). In other words, as a mental model, it would be throwing away more than a trillion dollars in the 2050s, then the 2060s then the 2070s then the 2080s then the 2090s before we started to see any benefits at all.
And in absolute dollars, even in inflation-adjusted terms, it would be even worse, as the economy would be growing. Even starting in the next century, the benefits each year wouldn’t come close to offsetting the costs. We would be locking ourselves into an immense cost (and net cost).
To me this is just incredibly profligate. It’s like the justification for the Iraq War (in this way): “trust us, it will pay for itself or close to it, we have to do it or face disaster, and we have to do it RIGHT NOW, stop raising all of these bothersome questions”. We are a wealthy country, but not so wealthy that we can literally burn more than a trillion dollars decade after decade on something that can demonstrate no appreciable benefits.