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Rising Temperatures Force Cities to Get Creative to Cool Off

Cities around the world are exploring ways to mitigate the effects of extreme heat and make urban areas cooler. Officials sometimes look to new technology to this end, but are also using low-tech devices, like trees.

A woman walking down the street holding a white cloth over her head to protect herself from the sun.
New technologies in pavement, smartphone apps and the age-old comfort of tree shading are all approaches cities are taking to deal with extreme heat.

“In the last two or three decades, the heat has changed. It has become much more longer, higher temperatures and more frequent,” said Eleni Myrivil, chief heat officer in Athens, Greece, during a panel discussion about how cities are mitigating the effects of heat. The panel was organized by CoMotion LIVE.

Myrivil was reflecting on the growing problem of high heat in her own city in Greece, but it is a sentiment seen in a number of cities in the United States and around the world. More and more, “chief heat officers” are joining the ranks of city leadership as urban areas brace themselves for dangerously high temperatures every year. Summer 2021 was the second hottest summer on record for North America, according to the National Oceanic and Atmospheric Administration (NOAA), behind 2012.

A number of cities have far-reaching long-range sustainability plans calling for transitions away from fossil fuel burning vehicles, mandates for rooftop solar, or bans on gas-burning appliances. However, those approaches are generally aimed at reducing greenhouse gas emissions, the root cause of global warming. What’s needed today, say urban heat experts, are plans to deal with, and mitigate, the heat currently afflicting cities.

Phoenix, Ariz., is exploring the use of “cool pavement” technology, where asphalt pavement is topped with a light-colored coating to reflect heat. Already, some 11 million square feet — 70 miles of streets — have been treated this way, said Ryan Stevens, engineering manager in the Street Transportation Department in Phoenix.

“We want the street to behave more like the natural desert surrounding,” said Stevens, in some of his comments on the panel, adding that the surface temperature is reduced 10 to 15 degrees during the height of the day — a noticeable reduction, especially in the hotter months.

“We also found that it decreases the actual asphalt itself from heating up as much,” he added, noting the interior of the pavement stays about 4 degrees cooler.

Portland, Ore., a city not generally known for oppressive summer heating, has also put in place a plan to make transit free during a “heat emergency,” which is when temperatures reach about 100 degrees.

“You can get on any bus or light rail, or streetcar, at no cost,” said Jonna Papaefthimiou, the new chief resilience officer in Portland.

The thinking is that since the cars are air conditioned, they allow riders — or anyone in need — to escape the heat.

“The driver will help you navigate to a safe place to stay cool,” Papaefthimiou added. The change in policy follows a deadly Portland heat wave last summer when temperatures reached 116 degrees and resulted in the deaths of 72 people.

On the other end of the country, officials in Miami have developed a “climate action strategy” to make the hot, muggy city more hospitable for walkers, cyclists and users of public transit. Miami boasts what may be the first air conditioned bus shelters in the nation. But the region is also exploring the wider use of vegetation and planting to make sidewalks and other public spaces more welcoming.

“The palm trees are cute,” remarked Carlos Cruz-Casas, chief innovation officer for the Department of Transportation and Public Works in Miami-Dade County, Fla., “and they look great on a picture, but they do nothing for shade. They do nothing for people walking or biking. So now, we’re trying to focus more on shade trees.

“We need to start to figure out a way to adapt to what’s going on,” he added.

Miami is focusing attention to how the public space beneath elevated metro-rail tracks — a 10-mile project known as the Underline — will be designed with shade in mind.

“There’s a plan to put a lot of trees and vegetation under that,” said Cruz-Casas.

Similarly, officials in Athens have developed a smartphone app that identifies a person’s risk to heat, depending on age and other factors. The app uses real-time data and offers advice about sheltering locations. The city has also added a “cool routes” feature for pedestrians and cyclists, which identify routes that may be shaded, have less car traffic, or are otherwise less exposed to intense heat.

“People need shade to walk and to bicycle,” said Myrivil.

“Basically, we’ve been figuring out where the hot spots are in our city, and trying to focus most of the heat mitigation actions in those areas,” she added.
Skip Descant writes about smart cities, the Internet of Things, transportation and other areas. He spent more than 12 years reporting for daily newspapers in Mississippi, Arkansas, Louisiana and California. He lives in downtown Yreka, Calif.