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The Most Important Number You’ve Never Heard Of

Michael Greenstone, one of the minds behind the social cost of carbon, has climate policy insights for the Biden administration.

Michael Greenstone

Michael Greenstone

Photographer: Andrew Harrer/Bloomberg

If prices for fossil fuels reflected their true cost to society—in deadly heat waves, water stress, disappearing crops—they’d be a lot higher than they are now. How much higher? Ask Michael Greenstone.

Greenstone is the Milton Friedman Distinguished Service Professor in Economics at the University of Chicago. In the early years of the Obama administration, he and legal scholar Cass Sunstein co-led the team that developed what’s known as “the social cost of carbon.” Think of it as the baseline value of a viable future—or, as Greenstone puts it, “the benefit, in money terms, of reducing carbon emissions.”