How Does One-Third the CO2 Emissions Cause Three Times the Climate Damage?

This month, the Environmental Protection Agency (EPA) published revised estimates of the social cost of carbon dioxide, methane, and nitrous oxide — the three main greenhouse gases emitted by industrial civilization. The EPA’s new estimates of the social cost of carbon dioxide (SC-CO2) are not only higher than those published by the U.S. government less than three years ago, but also weirder.

In a nutshell, the EPA’s new report estimates about three times as much societal damage from each ton of CO2 emissions than the government’s previous analysis. Yet the EPA also projects less than one-third the total quantity of CO2 emissions during the 300-year (2000–2300) analysis period.

A basic idea in analyses of the social cost of greenhouse gases (SC-GHG) is that the damage from the next ton of emissions depends entirely on the cumulative quantity of tons projected in the baseline. To infer dramatically higher per-ton social costs from dramatically smaller quantities of total emissions is quite paradoxical. Far from explicating this less-is-more paradox, the EPA’s 170-page report does not even acknowledge it.

Read the full article on National Review.