(FOX 46 CHARLOTTE) – On sweltering summer days, the Roof Above homeless shelter in Charlotte doubles as a cooling station. Air conditioning in the building, and more recently fans and misting units on the porch, provide respite from dangerous conditions outside.

“Heat is really tough on those folks that we serve,” says Randall Hitt, Roof Above’s vice president of engagement. “If you’re somebody who doesn’t have a place to call home, like you and I might have, it’s really hard spending hours outside when you’re talking about 90-degree-plus temperatures and a lot of humidity.”

An analysis of weather station data showed Charlotte was on average 2°F warmer last summer than it was in the summer of 1970, with 11 more days when the temperature reached 95°F.

As heat-trapping pollution continues to build in the atmosphere, cities and rural areas are getting hotter. Like most cities, Charlotte has been warming more quickly than surrounding areas because buildings, paved roads and parking lots trap heat during the day and release it more slowly overnight, compared with areas that have lots of trees and other plants.

This urban heat island effect pushes local temperatures on average 6 degrees higher than its surrounding rural areas, according to a recent analysis from Climate Central.

“If it’s already hot outside and then you get extra heat in the city, that’s where you start running into human health issues and heat stress and deaths,” said Dr. Matthew Eastin, an urban meteorology expert at the University of North Carolina in Charlotte. He has published research showing the urban heat island had nearly doubled in intensity between 1975 and 2014 in Charlotte.

High temperatures can harm health, particularly that of the elderly, children, pregnant women, individuals with heart and chest illnesses, outdoor workers and those experiencing homelessness.

From exhaustion, discomfort and nausea to excessive sweating, palpitations, and seizures, elevated temperatures, especially when stretched over several days, can cause health complications, says Liz Cary, a registered nurse who is on the advisory board of North Carolina Clinicians for Climate Action. Heat-trapping air pollution can worsen these health impacts by raising temperatures even further in cities.

Since 2010, the North Carolina Department of Health and Human Services has recorded 2,813 to 5,057 heat-related emergency room visits every summer across the state. Hotter summers led to more hospitalizations.

However, the impact of heat is likely to be much larger than is shown in the data, as only a fraction of people seek emergency care for heat-related illnesses. At the Roof Above shelter, for instance, a part-time nurse looks for signs of tiredness and dehydration during health checkups in the summer months.

The impacts of these warming trends are being felt unequally across Charlotte, and across the world.

Research shows neighborhoods that are home to low-income residents and communities of color are disproportionately hotter than those with predominantly white homeowners. Jeremy Hoffman, a climate scientist at the Science Museum of Virginia, led research that showed temperature differences can be as large as 20 degrees at the same time in different parts of the same city.

That’s because these hotter areas tend to be historically marginalized and underfunded neighborhoods in areas that were formerly redlined under racist federal urban policies. They contain more paved surfaces including asphalt lots, warehouses and industries, and fewer parks and trees that can cool the air.

“One of the first things cities can do is plan for reinviting nature into the city,” Hoffman said.

The city of Charlotte currently has 45 percent of its land covered by trees and the city aims to add another 5 percent to reach its 50 percent goal. Acknowledging that the existing tree canopy is not equally distributed, the city’s latest Tree Canopy Action Plan aims to “equitably and proactively expand the quality and quantity of the tree canopy for the benefit of all citizens of Charlotte.”

With increased daytime temperatures and reduced nighttime cooling when heat islands form, access to cool indoor spaces becomes important to protect those at risk.

For low-income communities who already live in warmer neighborhoods, air conditioning is often unaffordable. Day cooling centers like the Roof Above help, but people are unlikely to find relief late into the evening and night.

As the Queen City continues to grow rapidly, new developments bring opportunities to retain and incorporate green spaces through urban planning. Such natural cooling features would help protect future residents from increasingly extreme heat.

“It’s not something we can lackadaisically approach,” Dr. Eastin says. “We do need to take it seriously soon.”

This story was produced through a partnership between FOX 46 Charlotte and Climate Central, a non-advocacy science and news group.

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