My colleague Frank Ackerman, head of the Climate Economics Group here at SEI-U.S., has an excellent guest post today on TripleCrisis about how important it is that the EPA not under-price carbon. (Check out my posting from yesterday on the same topic: The lower their chosen price on carbon, the less pollution control seems justified.)

Here’s an excerpt of his argument:

Every $1 per ton of CO2 is about a penny per gallon of gasoline, so $5 per ton would be a trivial price incentive of 5 cents a gallon. At $50 per ton, or 50 cents a gallon, you’d start to notice. An increase of $500 per ton, or $5 per gallon, would put us in the realm of gas prices in many European countries where people buy smaller cars and use public transportation a lot more than we do.

$500, though, isn’t in the running. In the September proposal, EPA offered a range of values from $5 to $56. It sounds to me like the high end was included to mollify critics, while the low end is what EPA’s economists prefer.

Read the full post here. To learn more about the “social cost of carbon,” what’s wrong with the EPA’s approach, and how it’s likely to shape EPA motor vehicle regulations, read Frank’s critique of proposed EPA regulation here.