The U.S. Environmental Protection Agency forecasts the “social cost of carbon” (SCC) in the year 2020 to run anywhere from $13 to $137 per metric ton. That’s EPA’s measure of the harm each ton of “carbon” (really carbon dioxide, but who cares with our ill-educated public that doesn’t know the difference between an element and a compound—especially when the shorthand serves the purpose of scaring people needlessly?) emitted into the atmosphere.

Its estimates are based on a combination of computer climate models (that fail accurately to depict past global average temperature) and computer models of how ecosystems and economies will respond to rising temperatures.

But now three scholars have published a paper challenging those (and many other) estimates of the SCC based on empirically driven estimates of climate sensitivity (warming to ensue from doubled atmospheric CO2 concentration after all climate feedbacks have had their effect, i.e., in around two centuries). Kevin Dayaratna, David Kreutzer, and Ross McKitrick’s “Empirically-Constrained Climate Sensitivity and the Social Cost of Carbon” finds, on the basis of empirical studies, that he computer climate models exaggerate CO2-induced warming, and consequently all the models about any harms attributable to the CO2 also exaggerate.

How badly? Enough that after correction, one widely used estimate falls by 30% to 50%, and another by 80%.

And, indeed, it could even turn out that the SCC is negative—that is, that CO2 added to the atmosphere brings more benefits than harms.

Which means that we wicked Americans, who have higher CO2 emissions per capita than most people, may well by doing so be doing more good for the world than most, too.

The study’s worth careful reading.

 

 

Featured image “Per-capita carbon dioxide emissions: actual volume of gas in real-time” adapted from CarbonQuilt.org via Carbon Visuals, Flickr Creative Commons