My colleague (and blog contributor) Frank Ackerman has a new article on Grist that explains why the United States can’t afford to settle for the “social cost of carbon” estimate used in the fuel-efficiency and tailpipe emissions standards unveiled April 1.

As we outlined in our recent white paper, “The Social Cost of Carbon” (available on the E3 Network website), the $21-per-ton figure being used by the government as a “central estimate” of the damages caused by carbon dioxide emissions is based on flawed economics and questionable value judgments.

Frank’s article describes how the government came up with that number, and why the SCC is so important: It’s like a “volume dial” that determines how strict environmental standards should be. Even worse, as Congress considers a climate bill, the $21 SCC could be taken as the recommended level for a carbon tax or permit price:

If that happens, there is no way the United States could reach the widely discussed, science-based goal of cutting emissions by 80 percent by 2050, which would require a much higher price on carbon. Given how cost-benefit analyses dominate U.S. policymaking, a $21 SCC could have a devastating impact on environmental legislation.

It’s easy to think of the fuel-efficiency standards as yesterday’s news, and not discuss the SCC again until it comes up in Congress. But in fact, now is the time to do our homework and figure out what the true price of carbon should be – before that, too, is a done deal.