Louisville has consistently ranked among the worst urban heat islands in the country. Its vast areas of paved surfaces and declining tree canopy lead to much higher temperatures than surrounding rural areas.
But that problem isn’t limited to the city’s borders. It also extends across the Ohio River into Southern Indiana, especially in heavily-developed communities like Clarksville.
To combat rising temperatures, the Town of Clarksville and Clarksville Community Schools are partnering to participate in the Beat the Heat initiative, a grant program backed by Indiana University’s Environment Resilience Institute and the Indiana Office of Community and Rural Affairs.
“They started Beat the Heat with the goal of funding different cities and towns across the state for two years to really investigate extreme heat in their communities and to develop strategies to relieve the impacts of extreme heat, especially when it comes to public health,” said Clarksville heat relief coordinator Bronte Murrell.
Hot Summer Days
Clarksville is one of two Hoosier communities to receive the grant, along with Richmond. The town historically has about 17 days a year where temperatures reach 90 degrees or higher .
Clarksville has already met that benchmark 12 times this month. Forecasts call for it to happen five more times in the final week of August, which means Clarksville could match its annual average in a single month this year.
According to the town of Clarksville’s webpage about Beat the Heat, the number of 90-degree days will increase to between 36 and 38 by the 2050s. Murrell said satellite imagery of Indiana showed that the area around Clarksville, Jeffersonville and New Albany is one of the hottest parts of the state.
“Of course, some of this has to do with being the southernmost area of the state,” she said. “But it also has to do, in Clarksville, with having the development of I-65 [and] heavy commercial development. All of these darker surfaces — concrete, asphalt and dark rooftops — are going to retain more heat from light than lighter surfaces, like vegetation or white colored rooftops.”
Through Beat the Heat, Clarksville is also participating in the National Oceanic and Atmospheric Administration’s Urban Heat Island Mapping Campaign, which includes 18 towns and cities across the country.
Mapping The Heat
On Monday, a group of town officials, students and teachers completed seven routes — five in cars and two on bikes — in different parts of Clarksville to survey temperatures and create a heat map. CAPA Strategies, a company that helps communities and businesses plan for climate change, loaned equipment to volunteers in Clarksville to gather data.
Murrell said the data will be more useful than what’s collected by satellites.
“They’re driving around town with these heat sensors on their car and recording ground-level air temperatures — data that tells us what it actually feels like for a person in regards to heat, not just the surface temperature,” she said.
In addition to having higher temperatures than nearby rural areas, heat levels can also vary within Clarksville. Volunteers used an infrared camera to measure temperatures at different locations on Renaissance Academy’s campus before completing their survey routes on Monday.
The Importance of Trees
The blacktop in the parking lot had a surface temperature of 121 degrees. The temperature in a landscaped area dropped to 94 degrees, a decrease of 27 degrees from just a few yards away.
“The areas where you have lower tree canopy, you definitely see an increase in the overall temperature,” said Renaissance Academy science instructor David Gardner. “Any sort of living plant will reduce the overall heat.”
Gardner said students will help the town develop a plan to reduce temperatures in Clarksville once all the data is collected. Rebuilding the tree canopy, which has suffered in favor of shopping centers and their parking lots, could play an important role in that process.
“We can continue to identify areas to add more trees as a first big step,” he said. “And then over the next 15 to 20 years as those trees grow and mature, we will see the overall temperature drop.”
Gardner said the temperature drop will lead to decreases in energy use by Clarksville residents and businesses, which will further combat drivers of climate change. The U.S. Forest Service Center for Urban Forest Research found that planting three trees around a house can save as much as 30% of energy use.
Beat the Heat will also include public surveys where residents can detail how heat has affected their lives. High temperatures can worsen air quality, thus damaging the lungs and heart.
Clarksville High School senior Leila Sidahmed, one of four students to participate in the heat mapping effort on Monday, said it’s important for young people to find ways to address the warming climate. That’s why she’s happy schools are partnering with the town for the initiative.
“Since we are the next generation to be dealing with these problems, I felt like this was a great opportunity for us to go around, see what’s really going on in these areas and be able to see the data that we’re going to get back so that in the future, we know how to fix it,” she said.
Clarksville is in the second of five phases in the Beat the Heat program, which will end in summer 2023. Implementation of environmental changes, like improvements to the tree canopy and changes to future development requirements, could start in Clarksville by the end of 2021.