Extreme heat is becoming more frequent—and our infrastructure is going to need to adapt

By Adele Peters

Last Sunday morning, as temperatures in Portland, Oregon climbed to 112 degrees (a record high until the next day topped out at 116 degrees) a maintenance worker for the local streetcar system climbed out on a catwalk over a steel bridge to look for the source of a power outage. A cable had warped in the heat, wrapped around a piece of metal hardware, and essentially melted and ruptured. Elsewhere, two power substations gone out because the grid was overwhelmed, as people blasted air conditioning in a city that usually isn’t very hot. The streetcars, which run on electricity, were forced to temporarily shut down.

“We made the decision early Sunday afternoon to cancel service, so as we were having power coming on and offline, we weren’t stranding riders in 112 degree heat,” says Andrew Plambeck, public affairs manager at Portland Streetcar. “We also had the issue of our crews out there working in extreme conditions and risking their health.” The service shut down through Monday, and as the air began to cool on Monday night, workers came back to restore operation for the next morning.

The unprecedented heat in the Pacific Northwest, a region that was hotter than the vast majority of the planet last weekend, led to several problems in local infrastructure. In Portland, the heat also made cables sag on the light rail system, shutting it down, too. Some roads buckled in the heat; on others, tar melted and oozed. Vinyl siding warped on houses. An electric utility in Spokane, Washington, started rolling blackouts, taking out power for thousands of residents. In Seattle, which hit an all-time record high of 104 degrees, there were more power outages, and workers sprayed water on steel drawbridges to keep them cool enough to operate. Emergency rooms saw a surge in heat-related illnesses. In Northern California, as the heat dried out vegetation that was already dry from an ongoing drought, a wildfire erupted, threatening homes and shutting down a highway.

The heat wave has been called a once-in-a-millennium event, as an intense “heat dome” trapped hot air under a ridge of high pressure. But climate change is making heat waves more frequent—they now happen three times as often as they did in the middle of the 20th century. Most heat domes have happened since 1990, as climate change is changing jet stream patterns. Global warming is also making heat waves in the U.S. 3-5 degrees hotter than they were in the past. By the middle of the century, depending on how quickly the world addresses climate change, they could be another 3-5 degrees even hotter. If a city like Seattle, which might normally see 70-degree temperatures in June, suddenly has to contend with triple digit heat, how might infrastructure have to change?

Engineers might have to consider new standards. “The process of design is a risk assessment, right? You can’t design for everything,” says Steve Muench, a civil and environmental engineering professor at the University of Washington. “So where do you cut it off? To be really general, you kind of say, ‘Well, if it’s super rare, then probably it’s not worth spending the extra money and effort and materials to design for something that wouldn’t happen hardly ever.’ But if something normally doesn’t happen, and now it’s happening more frequently, we might need to rethink that.”

Transportation departments, for example, typically look at historical temperature data when making decisions about materials. “The asphalt that’s specified in Phoenix is different than the asphalt that’s specified here in Seattle, because they expect higher temperatures,” he says. If a road is going to last for decades, “you have to think kind of like, well, what’s it gonna be like in 30 years? Maybe that’s the temperature I should be thinking about.” Concrete slabs on highways can buckle if the temperature suddenly changes and makes them expand, something that’s more likely to happen on older roads. Tweaks to joints in the road can help reduce the risk, but cost more. Muench, who is working with the Federal Highway Administration on a project studying how to make pavement more resilient in the face of climate change, says that state transportation departments are beginning to think differently about how to plan.

In Portland, the local mass transit agency started working to make its system better able to withstand heat a few years ago, as summers continued to get hotter. But planners didn’t expect temperatures of 112 degrees. “We’re now coming to the conclusion that we need to invest some thought into how we, as an agency, can become more climate resilient,” Tyler Graf, the agency’s spokesperson, told IEEE Spectrum. “Things we were worried about happening seem to be happening now.”

Multiple other systems will also have to become more resilient to deal with more frequent heat waves. Electric utilities may have to rely more on solutions like paying customers to shrink energy use in order to avoid blackouts, and will have to plan for growing demand for power from air conditioning in places like Seattle, where it was rarely used in the past. Critical buildings, like health clinics and cooling centers, may need to add solar microgrids to ensure they have access to power and air conditioning if the grid does go down. As cities make changes to adapt to warming summers, such as planting more trees or giving homeowners incentives to add white roof coatings that can reflect heat, it can also help somewhat reduce urban temperatures.

The biggest part of the solution: tackling climate change. In a study that looked at how often American cities could face blisteringly hot days by the middle of the century, the Union of Concerned Scientists found that adopting strong climate policy would help dramatically shrink the risk. The more the global temperature creeps up, the more likely extreme heat waves will become—and the more it will cost to try to build cities that can survive them. Some warming will still happen, but “how much warming we see really depends on how quickly and how steeply we can reduce our emissions,” says Kristy Dahl, a senior climate scientist at the Union of Concerned Scientists. “We found that if we reduce our emissions in a way that’s consistent with keeping warming below two degrees Celsius—the goal of the Paris Climate Agreement—we would see the frequency of extreme heat increase through about the middle of the century, and then stay somewhat steady.” It could mean that adaptation is possible for cities, instead of an ever-changing goal.

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