Economists give the problems caused by climate change an appropriately dismal name: the damage function. To project just how much damage each U.S. county will incur by century's end, researchers ran 29,000 simulations of the U.S. economy, with results informed by weather-driven damages they detected in six domains–agriculture, crime, health, energy demand, labor, and coastal communities—between 1981 and 2010. Heat, for example, may increase crime or cause corn yields to fall, but it also could lower fatalities driven by exposure to the cold. The resulting prediction, though quite fallible in its inability to predict how humans will adapt to warming, foresees a country where, if fossil fuels continue to pour carbon into the atmosphere, the United States will divide further into a country of haves and have nots. Not surprisingly, Atlantic coastal communities are projected to take a toll from rising seas and strengthening hurricanes, but also much of the South and Midwest will be hurt by a decline in farming caused by rising temperatures, along with increasing energy demands to keep up with the heat. Meanwhile, states in the north and northwest could see their fortunes mildly boosted by warming, with farming yields rising thanks to shorter winters and less need to ward off harsh cold in homes. That’s not enough to counteract an overall negative trend for the country, which, if the planet warmed by 6°C from preindustrial levels, could suffer damage worth 6% of its gross domestic product, the team reports today in Science. The results, shown in the above map (red means total economic damage and blue is total economic benefit; projections are for 2080-2100), could guide states and the federal government toward the communities most in need of help adapting to the changed climate—should lawmakers choose to act.