Every City Is an Island
It will be 50 years this August since Summer in the City topped the Billboard charts for three weeks running. Professor Brian Stone Jr. of the School of City and Regional Planning had not even been born yet, but he is well acquainted with the heat island effect described in the evocative lyrics, which could cause even the coolest listener to break out in a sweat.
Those “sidewalks, hotter than a match head” the Lovin’ Spoonful sang about are only getting worse, according to Stone, also author of The City and the Coming Climate: Climate Change in the Places We Live and director of Georgia Tech’s Urban Climate Lab (UCL).
He and his research team are finding that, on average, cities are warming at double the rate of the planet — and much of that warming is driven by activities within the cities themselves.
“Cities are vulnerable places as far as temperature change,” Stone said. “The UCL’s principal mission, initially, was just to measure that. In recent years, we’ve expanded to work with cities to adapt to rising temperatures.”
The UCL’s distinctive niche is in contrast to the bulk of sustainability research conducted these days, Stone said. “Most environmental efforts are rooted in technology, like engineering cleaner cars or electricity. But we also have the option to reduce the demand side of the equation, and our focus on land use provides a perspective and policy arena from which to address environmental issues.”
Rising Tide of Extreme Heat
Conducting studies around the nation, the UCL has found that Louisville, Kentucky, is the most rapidly warming metropolis in the U.S. relative to what’s around it. (Atlanta is No. 3.) The UCL has helped Louisville develop a heat adaptation plan — the first for a U.S. city.
Currently, the UCL’s largest project, funded by the National Science Foundation, focuses on the growing risk of having a heat wave and a blackout at the same time. “That may be one of the most threatening events we can imagine,” Stone said, “and cities are not well prepared for it.”
Stone has been interviewed by WSB-TV, CNN, and NPR, and he’s been the go-to expert for Forbes, USA Today, and The Washington Post, among other publications.
The media always seem to call when it’s getting really hot out, Stone has noticed. “It’s during heat waves that cities struggle the most,” he said. “If you’re New York or New Orleans and you have rising sea levels due to global warming, it would be expensive, but you can build a wall — there’s no barrier for the rising tide of extreme heat.”
The challenge for cities in the face of climate change, then, is both global and local, Stone said. City planning and smart growth can certainly play a role in reducing fossil fuel consumption and the corresponding greenhouse gas emissions, but his group is also working to make sure the “greenhouse” effect is not compounded by the “green loss” effect. “We cut down trees, we build parking lots and buildings — it heats up the environment,” Stone said.
Converting Asphalt to Green Space
Stone says Georgia Tech is the perfect academic environment for conducting his urban climate research, citing the interdisciplinary scientific, technological, and public policy expertise at his disposal. But the campus itself also plays a role — as a living laboratory.
The UCL has positioned 24 small-scale weather stations around campus to measure not only temperature changes but how different projects impact temperatures.
“Georgia Tech is one of the only places in the city where we’re actually converting asphalt to green space,” he said. “We’re tearing up parking lots and putting in quad space, so we can measure before and after how that’s cooling the air.”
The Good News for Cities
The good news for cities as they adapt to climate change is that they don’t need a mandate from the global or U.S. policy community, Stone said. “They are empowered through their land use authority and policy tool kit to significantly slow the rate of warming.”
Certain policy prescriptions will be part of almost any heat mitigation plan for cities, Stone said. Approaches such as expanding and incentivizing transit; encouraging high-density development; and creating better bike and pedestrian networks can have a direct effect on maintaining green cover and reducing waste heat emissions. For other strategies, he said, cities and environmentally conscious individuals should think “green, white, and blue”:
- Plant and preserve trees, especially to shade impervious surfaces.
- Install green roofs, like the one on Clough Commons.
- Promote parks and community gardens.
- Use reflective roofing materials and reflective paving.
- Build stormwater ponds, such as the one at Old Fourth Ward Park.
- Create rain gardens.
Learn more about Stone’s work at www.urbanclimate.gatech.edu.
Brian Stone is a professor in the School of City and Regional Planning in the College of Design and director of Georgia Tech’s Urban Climate Lab. Stone studies the urban heat island effect, which turns cities into cauldrons because of the combined impact of climate change and rising temperatures driven by a predominance of concrete and a shortage of vegetation.
This map displays urban heat island (UHI) intensity for average maximum air temperatures over July 2015. The map shows air temperature differences between select campus locations (black circles) and a nearby natural space, the urban forest within the Atlanta Botanical Garden, which served as a rural reference point for air temperature comparison.
This map displays urban heat island (UHI) intensity for average minimum air temperatures over July 2015. The map shows air temperature differences between select campus locations (black circles) and a nearby natural space, the urban forest within the Atlanta Botanical Garden, which served as a rural reference point for air temperature comparison.