WeatherImpact Earth


Using technology and trees to lower the Phoenix temperature

Downtown Phoenix
Posted at 3:29 PM, Jun 01, 2022
and last updated 2022-06-27 16:11:14-04

PHOENIX — Once a month, Ernie, a retired cop from Washington, comes searching for treasure in Cesar Chavez Park.

"What did you find? A quarter," he said.

Ernie says he moved to Phoenix because of the heat. But he admits it's not for everyone. "It does get hot for some of these people, and I see a lot of people, boom, go over. It's not a pretty sight," he said.

Indeed, Phoenix is becoming nearly unlivable during the summer. It is now considered the hottest city in the United States. According to the Maricopa County Health Department, there's been a 400% increase in heat related deaths from 2014 to 2021. Nearly 200 people died from extreme heat in Phoenix in 2020, making it the hottest, driest, and deadliest summer on record. 53 days of temperatures reaching 110 degrees or higher.

When it comes to heat, not all neighborhoods are created equally. In south Phoenix and Maryvale for instance, a combination of heat-absorbing roofs and streets as well as a scarcity of trees makes them two of the hottest spots in town. "This is a heat equity story that we are working to change," says Dave Hondula, the Director of Heat Response and Mitigation for Phoenix.

Hondula is Phoenix's heat czar. He oversees a four-person team, the first ever created by a U.S. city whose mission is to lower the heat. "We're trying to think about the long-term strategies that can cool the city and make it more comfortable. And the short-term strategies that protect people when it's hot," Hondula said.

There are more than 4,800 miles of public streets in Phoenix. When the temperature reaches 110 degrees, the heat coming off the pavement can reach 130 degrees or higher.  After a successful test run in some Phoenix neighborhoods last year, the city launched its Cool Streets Program this summer. 40 to 50 miles of neighborhood streets across the city are being resurfaced with a reflective material.

"The road doesn't heat up. It doesn't re-admit that heat into the atmosphere. We get that solar energy out of the system right away," Hondula said. "We've seen really promising results so far. The road surfaces are 10-11-12 degrees Fahrenheit cooler."

Phoenix is also working with the non-profit American Forests, planting trees throughout the city. Earlier this year, 200 ash and evergreens were planted along Baseline Road and around Cesar Chavez Library.

Next week, the City Council will decide if it will use American Rescue Plan funds to finance tree plantings in 25 Phoenix communities, eventually creating tree canopies that will help provide shade. "Goal number one is to create a city in the future that is cooler and more comfortable for everyone," Hondula said.

The more immediate goal is to reduce the public health impact of heat. That means more cooling centers, hydration stations, and teaching city workers to recognize heat danger.