All the asphalt and cement in cities can make them heat up more than the areas around them. It's called the urban heat island effect, and University of Georgia researchers recently conducted a study to figure out which had more effect on the phenomenon: density or sprawl?
It turned out, it's not an either/or answer.
“Sprawling and high density city configurations both can increase urban heat island intensities,” said Neil Debbage, a graduate student at UGA and the lead author on the study.
What really makes a difference is how continuous urban development is, he said, if it's all concrete for miles, or if there are trees and parks. Out of the 50 biggest cities in the country, Atlanta ranked 31st, in terms of how intense the heat island effect is, said Debbage, probably thanks to all the trees.
“If we can break up the urban development, that would hopefully mitigate the urban heat island effect,” he said.
Having that understanding is valuable, said Marshall Shepherd, director of UGA’s atmospheric sciences program and a co-author on the paper.
“It is in our best interest as people flock more to cities to live and work that we continue to try to find ways to design or plan cities to mitigate this heat island,” said Shepherd.
Especially, he said, as the climate warms.
“When you add the urban heat island effect to the increasing background warming that we see because of the anthropogenic greenhouse-related warming,” he said, “you have a double-whammy, if you will, in cities.”
But cities can also do a lot to keep the effects from getting too bad, said Marshall. While one city can’t change global temperature changes, it can plan differently.
That’s something Chandana Mitra, a climatologist at Auburn University who was not involved in this study, is advocating for.
“It is time that the stakeholders and the planners should start having climatologists and meteorologists on their team when they plan a city,” she said. “One good example is Hong Kong where architects, planners and climate scientists are working together to plan new establishments. That should be the future of urban planning.”
The paper was published in the journal, Computers, Environment and Urban Systems.