Fighting global warming on a global scale is a monumental, and very complicated, task. In Louisville, Ky., officials are looking to combat warming on a much smaller scale, with one relatively simple method: planting trees.
The Courier-Journal reports on a recent presentation by Brian Stone, a researcher at the Georgia Institute of Technology, to a city tree commission. As in many cities, the concentration of pavement and dark roofs in Louisville helps create a heat island. It’s a particular issue in the Kentucky city, which Stone says has some of the weakest ordinances encouraging the growth of trees. Tree canopy covers only about 30 percent of the metropolitan area, and as little as 7 percent of the city center, compared with 50 percent of some other Southern urban areas.
Stone and fellow researchers studied how much hotter cities were than surrounding rural areas, and how much that differential has changed over the past 50 years. By that measure, Phoenix and Atlanta have fared the worst, but Louisville is also getting increasingly sweaty. Stone and other GIT researchers have created an interactive map showing how certain cities have heated up more than others. Urban trees may often be seen as a luxury, but Stone points out that they are really a health issue, because rising urban heat can be dangerous.
“This is the most significant public health threat of climate change at the urban level,” he said.
The location of trees matters too. Those planted along streets are most useful because they shade asphalt, which quickly heats a neighborhood when it’s exposed to the sun.
Louisville is considering various measures to encourage more tree growth. Currently, the city generally doesn’t require public agencies or landowners to replace trees they cut down and doesn’t provide city care for trees in public rights-of-way.
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