States and localities across the U.S. are already experiencing profound weather shifts associated with climate change, from rising sea levels and flooding to drought and dangerously hot summers. Economists have long been warning that these changes will come with a cost. But until now, there’s been no measure of what that cost might be for individual counties.

A study published in the journal Science in June is the most extensive model available of what climate change could cost the United States, county by county. (View an interactive map at the bottom of this article). The study is the first of its kind, linking climate projections with economic effects like mortality, labor productivity, energy demand and crop yields.

By far, the largest economic cost across the U.S. is loss of human life to heat-related injuries. Huge swaths of the South could see these kinds of deaths spike to more than 20 people out of every 100,000. In addition, energy costs will increase as people use air conditioning more often, labor productivity will suffer for those who work outdoors, crop yields will decrease and rising seas will swallow up valuable coastal properties.

The findings are striking for their specificity and their prediction of growing inequality spurred by climate change.

According to the study, the American South and lower Midwest will bear the brunt of the economic costs associated with climate change through the end of the century.

“It turns out that the areas that are preferentially harmed by warming are also areas that tend to be poorer on the whole,” says Robert Kopp, a lead author of the study and a climate policy scholar at Rutgers University. “And that’s just because of where they happen to be and what their climate already is.”

In other words, it’s dangerous and harmful for the hottest swaths of the country to get any hotter. The most at-risk county, according to the study, is Florida's Union County, which stands to lose 28 percent of its income from 2080 to 2099. (To be clear, these are effects measured against what income would have been without warming, not against what income is currently.)

In northern areas with a cooler climate, warming won’t have a negative economic effect, at least not through the end of the century -- and could even create some positive economic outcomes, says Kopp. That's because some crops might respond better to balmier weather in the North, and fewer people will die from cold.

Several counties in Washington state, Oregon, Idaho, Colorado, Wisconsin, Michigan and even Nevada will experience some benefits through 2099. Mineral County, Nev., will experience the greatest economic boost, with a 13 percent increase in income.

In the worst-case-scenario modeled by the researchers, temperatures could increase by up to 10 degrees Fahrenheit by the end of the century. If that happens, the poorest counties in the country could be hit with anywhere from 2 to 20 percent income loss, according to the researchers. Such a loss would hurt the workers and the local governments that rely on their income tax revenue, and would exacerbate income inequality in the country.

Counties in Florida will be particularly hard-hit, along with places in Texas, Georgia, Alabama, Louisiana and Mississippi. According to Kopp, this is a result of several overlapping factors.

“In Florida, you have a really large coastal effect. On top of that, it’s already a very warm climate and you have a lot of elderly people living there [who are more susceptible to heat injury],” he says.

Kopp cautions that the study model has some limitations. For one, it assumes that people will stay put through the worst warming effects.

“This probably means that we’re overestimating the amount of harm to the country because people will react and shift where they live and where they invest,” he says.

But other outside experts have pointed out that the study could actually have underestimated some damages. For example, an unexpectedly rapid disintegration of the ice sheets in Antarctica and Greenland would drastically worsen economic effects along the East and West coasts.

Still, the study provides a valuable blueprint for local governments and citizens to avoid, or at least plan for, the negative economic effects of climate change.

“If you’re making investments that are going to last for decades, you'd better be aware of how the environment will change ... coastal investments, for example, and transportation investments,” says Kopp. “Also, if you’re a bond-writing agency and you’re rating bonds without thinking about how the government will be affected by climate change, you’re not doing your job.”

Counties shaded red on the map are expected to incur greater damages, shown as a percentage of county GDP. Those with negative damage estimates are expected to experience economic benefits.

Click to see data for each county. See below the map for explanations of each category.

Agriculture: Changes in average yields for corn, wheat, soybeans and cotton

Energy Spending: Change in electricity demand

Mortality: Change in mortality rates for all causes of death

Low-Risk Labor: Change in labor supply for jobs where workers are "minimally exposed" to outdoor temperatures

High-Risk Labor: Change in labor supply for jobs where workers are "heavily exposed" to outdoor temperatures

Coastal Damages: Changes resulting from storms and sea level rise

Property Crime: Changes in violent crime rates

Violent Crime: Changes in property crime rates

Map by Mike Maciag.