Rochester-area ‘heat islands’ make heat waves even worse

Jul 19, 2019

As historically high temperatures move through much of the United States this weekend, urban areas are likely to take the brunt of them.

That’s because of an effect called the “urban heat island” – but there are ways to mitigate it, if you know where to look.

Rochester Institute of Technology professor Karl Korfmacher says even small islands of vegetation can help reduce the heating effects of large parking lots.
Credit Brett Dahlberg / WXXI News

Standing in the middle of the South Town Plaza parking lot in Henrietta on Friday, Karl Korfmacher, a professor of environmental science at the Rochester Institute of Technology, surveyed the scene.

“There’s a large expanse of asphalt,” he said. “Black asphalt. And if you look out here, you’ll see very little vegetation.”  

Cities and suburbs in the United States are loaded with this kind of space: expansive blacktops with precious little shade. To Korfmacher, these areas are basically big, outdoor warming ovens. They can make hot days even hotter, and they can lengthen heat waves because they hold onto their heat even overnight.

That heightens the risk for people who are vulnerable to heat-related health problems, like older populations and people who don’t have air conditioning at home.

More than 2,600 people died of heat-related causes in the last five years of data available from the federal Centers for Disease Control.

But Korfmacher said it doesn’t have to be this way. Even in this desolate parking lot, he found an example of how developers can reduce the effects of urban heat islands.

“This is just a little vegetation island in the parking lot. You can already see on this that there’s moisture,” Korfmacher said.

“If you put your hand on it, it’s noticeably cooler than the asphalt.”

The banks of the Genesee River provide examples of how municipalities can reduce the effects of urban heat islands, says Karl Korfmacher, a professor of environmental science at the Rochester Institute of Technology.
Credit Brett Dahlberg / WXXI News

Korfmacher said nature provides lots of examples of ways to mitigate urban heat islands. At a quiet spot on the Genesee River, he pointed out the greenery.

“We’ve got grass all around us. Any time you’ve got vegetation in an urban setting, you are going to be helping to cool it off a little bit,” Korfmacher said. “Shade’s also going to cool the buildings themselves."

The closer we can get to having our cities look like natural ecosystems, the better off we’ll be in heat waves, Korfmacher said.

Local municipalities are making some progress in that direction. In Henrietta, where South Town Plaza is located, town Supervisor Stephen Schultz said he talks to developers about “land banking,” which encourages them to let grass grow over empty parking areas when they’re not in use.

Schultz and other local officials said trees are a substantial part of their plans to mitigate heat islands in their borders.

“It really is kind of simple, when you think about it,” said Michael Guyon, the public works commissioner in Brighton. “You plant trees. You use light colored pavements. When you need a new roof, you choose a white one.”

In an area like Rochester, though, there are some challenges. Trees are struggling in Monroe County. And Norman Jones, who heads Rochester's Department of Environmental Services, said the ice storm of 1991 wiped out wide swaths of the tree canopy.

“We had to really start doing things differently,” he said.

Now, part of City Hall is covered with a green roof, which uses vegetation to absorb heat. The city is looking to expand community gardens and replace some sections of pavement with small green spaces.

“These are maybe small steps, but taken together, they can make a substantial difference,” Jones said.