Urban Development Is Making Dallas Hotter. This Study Says More Trees Are The Answer | KERA News

Urban Development Is Making Dallas Hotter. This Study Says More Trees Are The Answer

Apr 18, 2018

Dallas is warming at a faster rate than any other large city in the country, besides Louisville, Kentucky and Phoenix, according to research conducted for the Texas Trees Foundation.

The foundation worked with the Urban Climate Lab at the Georgia Institute of Technology to conclude that urban development is making Dallas a hotter place to live — literally.

Matt Grubisich, the foundation's director of Operations & Urban Forestry, estimates almost 35 percent of Dallas is covered by impervious surfaces, like concrete and asphalt, which create an "urban heat island" effect. 

"It can cause areas to be as much as 15 degrees warmer than more rural areas, or areas where we have more tree canopy cover," Grubisich said. 

 

Interview Highlights

On Dallas' lack of trees contributing to warming

What we actually found in our study was that trees are two times more effective in combating the urban heat island effect than even things like "green roofs," where plants and vegetation grow, or "white roofs," painted roofs which reflect more heat rather than absorb it. As we add population, we have to add that infrastructure, but it's about having that balance between "green infrastructure" (trees) and what we call our "gray infrastructure" (roads).

On what this heating trend means

When we talk about urban heat islands, they don't cause heatwaves — they amplify them. People tell me all the time, "Well, it's always been hot in Dallas." When you combine that with an urban heat island effect, you get extreme temperatures. So our extremes are no longer 101, 102 degrees, our extremes become 115, 120 degrees. Our bodies aren't made to regulate that temperature and so it becomes a very dangerous situation, especially if you combine that with a power outage from increased air conditioning use, or if you don't have air conditioning, or if you have pre-existing conditions, like asthma or a heart condition. 

On what a city can do to offset heat gains

It's all about city planning. What will Dallas look like in the future? Do we want it to be a healthy and clean place for us to live, or do we want it to be miserably hot? It's how we design our streets, how we design our new developments, how we design the city to be more bike friendly, walk friendly. But then it's also about how do we increase the use of green infrastructure into our new development to make sure that we have that balance going forward? Then it's looking at things outside of the box, like "white roofs" and "green roofs" and canopy cover in our parking lots. That doesn't just affect the urban heat island effect but also starts to affect things like storm water management and overall community health.

Interview responses have been edited for clarity and length.

Explore the full study

Texas Trees Urban Heat Island Study by KERANews on Scribd