Charlotte drought highlights disparity in tree canopy

TREES CHARLOTTE

Neighborhoods with ample tree canopy tend to have cooler temperatures and better air quality than those that don't.

Charlotte is under an extreme drought.

North Carolina is in the middle of the third-driest January-March on record since 1895. March was the fifth-driest March on record since 1895 with 1.85 total inches of precipitation, which is down 2.44 inches from the normal average. 

During periods of drought, one thing that sometimes goes overlooked is the importance of trees in combating the impacts of drought. In urban Charlotte where asphalt is every and trees are disappearing, it remains hot and drought impacts are heightened. 

Allison Rhodes, executive director at TreesCharlotte, said trees play a vital role in keeping people cool year-round. 

“The trees shade the ground and the air surface,” she said. “Think about it like this: when you walk into a forest, you notice that it feels cooler and then the ground is damp. That’s because the trees are helping to keep the air cool. The rain falls, the trees soak up that water, and then they slowly help release it into the ground and into the air, to keep more moisture in the air and to keep the temperature cooler.”

In neighboring Gaston County, the city of Gastonia and Two Rivers Utilities are urging residents and businesses to conserve water after the Catawba–Wateree Drought Management Advisory Group declared a Stage 1, or voluntary advisory for the Catawba–Wateree River Basin.

The Catawba–Wateree Drought Management Advisory Group is an alliance of water utilities as well as cities, businesses and Duke Energy that rely on the basin’s water. The goal is to reduce consumption by 3-5%.
Trees — whose numbers over the last four years have drastically decreased — lower heat by creating shade and releasing water vapor through their leaves. They also protect people from heat-related injuries. 

“The number one environmental killer is heat,” Rhodes said. “And a lot of people don't know that. They think it's hurricanes or floods or whatnot, but it's actually heat. It is the number one killer for people. So obviously, people that are sensitive, that have health issues, or elderly people, they’re more prone to that. 

“If there’s not a tree in your yard or shade, it could be crucial. You see workers outside, if they don’t have a place to go in the shade and rest and cool down, their bodies will overheat and they’ll get heat stroke and other things that could be even worse.”

Another key contribution of trees is air quality. According to the Centers For Disease Control and Prevention, drought degrades air quality by increasing particulate matter in the atmosphere. 

“Trees are natural air scrubbers,” Rhodes said. “They make the air cleaner. CleanAire [NC] has a great program where they are testing the air quality through all of Charlotte and areas like Myers Park especially have higher air quality than areas like Derita. A lot of that has to do with not only the lack of tree canopy (in lower-income neighborhoods) but also the businesses that are in those areas. If you had trees around those businesses, it would help offset some of the pollutants that those businesses are putting out.”

According to Mecklenburg County records, the tree canopy in the last 20 years has dropped 5% in large part due to  development. TreesCharlotte’s socio-demographic analysis indicates that parts of west and east Charlotte along with uptown have some of the lowest percentages of active tree canopy and as a result tend to be hotter on average. In times of drought, it’s amplified. 

“With the west side, they have a lot of impervious surface,” Rhodes said. “So, they have a lot of concrete, a lot of asphalt, not a lot of grass. So those parts of town, if you look at heat maps, are hotter for that reason, because they don't have impervious surfaces. And that's one of the reasons that it causes it to and it makes everything drier, because the trees add water to the air. … When you cut down trees it can make areas anywhere from 10 to 30 degrees warmer in those areas with a lack of trees.” 

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