Yet beyond its initial findings, the paper represents a major breakthrough for the field of climate economics. Previously, the best financial forecasts of climate change approximated damages for the entire country at once. This new study worked from the bottom up, building its model from dozens of microeconomic studies into how climate change is already affecting regional economies across the United States. Every algorithm in the model emerges from a previously observed relationship in real-world data.

“This is like the adults entering the room. Economists have, for a quarter century, insisted that more work needs to be done to estimate climate damages. This team has done so,” said Gernot Wagner, a researcher Harvard University and the former lead senior economist at the Environmental Defense Fund, in an email. He was not connected to the study.

But this emphasis on the observed means that the research omitted many serious risks of climate change—even those the researchers considered important—if the data describing them was too paltry. The estimates do not include “non-market goods” like the loss of biodiversity or natural splendor. In other words: Most people agree that dead polar bears have an economic cost, but there’s no consensus on how to approximate it.

The study also doesn’t account for the increased likelihood of “tail risks”—that is, unlikely events with catastrophic consequences. Many researchers believe that global warming will make social strife, mass migration, or global military calamity more likely, but those events are, by definition, hard to predict. The same goes for economic disaster prompted by the onset of a “mega-drought” or the rapid collapse of the Greenland ice sheet.

“When we had the Dust Bowl, we saw everyone clear out of the Midwest and flood labor markets in the urban centers on the coast,” said Hsiang. Nothing like this kind of internal migration is modeled in the Science study.

All in all, the study’s assessments should be interpreted as the most rigorous attempt ever to describe what global warming will cost the United States in a “normal” world. It describes an America that has retained a well-organized economy, held together as a political community, and benefitted from the ongoing general global peace that began 70 years ago.

Even in that harmonious world, climate change will make the United States pay.

What Climate Change Will Cost Every U.S. County, 2080–2099

(Kopp, Hsiang, et al. / Science)

Across the country’s southern half—and especially in states that border the Gulf of Mexico—climate change could impose the equivalent of a 20-percent tax on county-level income, according to the study. Harvests will dwindle, summer energy costs will soar, rising seas will erase real-estate holdings, and heatwaves will set off epidemics of cardiac and pulmonary disease.