In a state widely known for scorching summer days, the prospect of even hotter weather can’t be reassuring for South Carolina’s more than 5 million residents.
But by the middle of this century, the number of sweltering days in the Palmetto State is forecast to increase by more than 350 percent if little or nothing is done to stop man-made climate change. By the end of the century, the increase could approach 600 percent.
Those are key conclusions in a report released Tuesday that shows the United States is heating up rapidly as the earth’s climate changes. Increases in the number of days with extreme, dangerously hot weather can be expected to rise sharply in hundreds of cities across the country, researchers say.
Researchers at the Union of Concerned Scientists say it’s already too late to prevent all of the rising heat, but the country can slow down the trend with aggressive action to halt man-made global warming. If the country takes no action, the number of dangerously hot days is expected to skyrocket in many areas, most notably the Southeast, according to the environmental group’s report. Rising earth temperatures are resulting from increases in carbon dioxide and other greenhouse gases that trap heat in the atmosphere.
“Within the next 20 years, many people in the United States will be faced with heat unlike any they have dealt with before,’’ the study said.
The study forecasts the average number of days in South Carolina with a heat index above 100 degrees to increase from 14 annually to 64 by the middle of the 21st Century. By the end of the century, the average number of days with a heat index of 100 would rise to 97 annually, the report says. That would affect virtually all of the state’s more than 5 million residents, unless the country takes action to reduce greenhouse gas pollution, the study said.
People should pay attention to the study because a high heat index is a measure of how people’s health is affected by heat, researchers said. A heat index, like that used in the report, gives people an idea of how hot the weather feels when they go outside. It’s a similar concept to wind chill factor, which shows how cold the weather feels in winter.
A heat index exceeding 100 degrees, for example, makes it more likely that elderly or less healthy people will suffer “heat stress or illnesses,’’ the report said. A heat index of 105 means even healthy adults are at risk, according to the study.
Columbia, Charleston, Hilton Head Island and Florence are among the cities in South Carolina that will feel more sweltering days, according to the report.
In Columbia, a city with notoriously high summer temperatures, the number of days with a heat index of 100 or more would rise from 15 days per year to as many as 65 by mid-century if no action is taken to stop climate change. With modest action to stop global warming, the city would still see 49 days with heat indexes topping 100 degrees, the report says.
The capital city can expect an increase in days with a heat index topping 105 to rise from five to 37 days each year by mid-century if no action is taken, the study said.
Erika Spanger Siegfried, a co-author of the report, said the projected increase in blazing hot days in South Carolina is typical of what to expect throughout the southern U.S., a region with humidity levels that make high temperatures feel even hotter.
“We were really struck by the impact across the entire Sunbelt,’’ she said. “You see some of the most significant increases in the number of big cities that will face relentless heat.’’
Nationally, the rise in extreme heat days would threaten “the health, lives and livelihoods of millions of people,’’ the study said. Hundreds of cities would be affected by the increasing number of days of extreme heat.
The Union of Concerned Scientists is a national environmental group founded by scientific researchers and university students. The organization studies various aspects of environmental issues. The report, which relied on federal and international climate data, was released on a day when many people in the Southeast are in the grips of searing heat.
Columbia, located in the center of South Carolina, will have heat indexes of 100 to 105 during the next week, according to the National Weather Service. Temperatures approaching 100 degrees are expected this week, said NWS forecaster Chris Rohrbach.
Tuesday’s report is the latest forecasting higher temperatures in the future.
Already, the country is feeling the effects of climate change, said University of North Carolina professor Charles “Chip’’ Konrad, a leading regional authority on global warming. Konrad, who was not involved in the Union of Concerned Scientists study, told The State recently that cities like Columbia are particularly susceptible to rising temperatures because they have so much pavement.
“We know the climate is warming up,’’ he said. “It’s getting hotter in Columbia, not only because of this intensifying urban heat island, but also because of climate change. There is no scientist in the country that would doubt that. It is a problem that is only going to get worse.’’
John Ruoff, a researcher and advocate for the needy in Columbia, said disadvantaged people can expect to feel the impact of more hot days in the future. Many don’t have air conditioning, and those who do often are reluctant to use it because it drives up their monthly power bills, he said.
“It ain’t fun now, and if it keeps getting warmer, it’s going to be even worse,’’ Ruoff said, noting that programs to help the needy keep cool eventually won’t be enough. “Most of the assistance you see available is to get fans for people, particularly for elderly folks. But it gets to a point where even fans are not going to do enough.’’
Climate change is having an array of impacts around the world, ranging from coastal flooding to more intense storms. But the Union of Concerned Scientists report says heat may “affect daily life for the average U.S. resident more than any other facet of climate change.’’
While consensus is widespread that global warming is a problem, how to resolve it has sparked debate. President Donald Trump has dropped many of the initiatives that were under way to address global warming, such as participation in the international Paris climate accord. He has pushed a business friendly agenda, saying the government needs to loosen job-killing regulations.
But others say that’s the wrong path, given the impacts the nation is seeing — and will continue to see as the earth heats up. A key way to do that is to curb emissions of carbon dioxide and other greenhouse gases, many say.
“If we wish to spare people in the United States and around the world the mortal dangers of extreme and relentless heat, there is little time to do so and little room for half measures,’’ the Union of Concerned Scientists report said. “We need to employ our most ambitious actions to prevent the rise of extreme heat.’’