Life in a Hot Dome: The American West is Figuring Out How to Stay Cool

From planting trees to painting streets white, American cities are fighting extreme heat.

“The opportunities for mitigating the heat in the US are huge,” says Steffen Lehmann, director of the University of Nevada. Urban Futures Lab. “The knowledge is there, but the things that need to be done are not being done. It’s extremely frustrating.”

AROUND 80% of America’s population live in urban areas – where the heat island effect can drastically exacerbate the impact of hot weather. Urban heat islands are densely populated, built-up areas with few trees and large areas of concrete and dark asphalt that absorb the sun’s energy. As the sun sets, the man-made materials release stored heat – ensuring the city stays warm, even at night. Urban heat island temperatures can be up to 11C (20F) hotter than less populated areas.

As American cities continue to experience record-breaking, life-threatening days in the triple digits, researchers like Lehmann say many areas are still unprepared. In 2022, a group of scientists examined 175 city ​​plans of the municipality of the 50 most populous cities in the US. Although most mentioned heat, “few included” strategies to deal with it, the report said.

“If cities are not providing a complete picture of heat – how chronic it is and its diverse impacts on the ground – we will not be able to fully protect residents and may exacerbate existing social and environmental injustices,” says co-author Emma. French, a doctoral student in urban planning at Los Angeles University College.

Another study found that 41 million people live in areas with extreme urban heat island temperatures. report, from Central Climate, found that 14 cities had an extreme contrast between temperatures in urban areas versus surrounding less developed areas. These included Albuquerque, Bakersfield, Fresno and Las Vegas.

The problem is “too much talk and not enough action,” says Lehmann. “It’s extremely difficult to make a difference.” It’s hard to hold up a city as a model case study when it comes to mitigating the heat, Lehmann continues, because nowhere else in the U.S. does it well.

“But”, he continues, “I am optimistic, because there ARE things cities can do to calm down. And I think a change of mentality is happening.”

In Tuscon, Arizona, drought makes planting trees even more difficult in low-income neighborhoods, where residents often do not have the opportunity to plant or maintain trees in their gardens. The city runs a rebate program to reimburse residents up to $2,000 (£1,563) for installing rainwater harvesting systems, where the water can be used for trees and green areas. This includes loans and grants with zero interest for communities with economic challenges, as well as offering seminars in Spanish.

Data collection plays an important role in planning for the future when it comes to heating.

In 2022, 60 volunteers are measured morning, afternoon and evening temperatures across Clark County, where Las Vegas is located, as part of a heat mapping study funded by the National Oceanic and Atmospheric Administration. of the map produced from that data shows elevated temperatures are worst in North Las Vegas, East Las Vegas and downtown, which could be up to 6C (11F) hotter than other parts of the city. The county is now using the data to inform heat mitigation policies, which include community cooling centers and tree planting initiatives.

In Albuquerque, New Mexico, the city worked with local volunteers to map temperature and humidity by distributing specially designed thermal sensors. Residents drove or biked along designated routes twice a day to record more than 67,000 temperature points. The maps showed variations of up to almost 9.4C (17F) in different parts of the city, with the hottest temperatures in the city center and neighborhoods adjacent to highways. again, the most affected neighborhoods were low-income communities. The city then joined NASA to acquire satellite imagery, which was overlaid with social vulnerability data to target frontline communities.

The city had never done anything like this before, and the data allowed the city government to plan heating accordingly, according to who needed help the most. “That led to two important strategies that we’re implementing now,” says Albuquerque’s sustainability officer, Ann Simon. One is a community energy efficiency program where low-income families are helped to maximize energy efficiency in their home and reduce their energy bills by around £233 ($300) a year. To date, the city has made improvements to 104 homes.

“We’re a small program, but we just got a huge $2 million grant to help more families, so we can help sixfold the number of families we serve,” says Simon.

Nasa will also image the neighborhoods again, which Simon hopes will inform future planning.

“Just a few years ago, very few cities were talking about preparing for rising temperatures, so it’s an important step that heat is becoming a bigger part of the conversation,” says V. Kelly Turner, professor of urban planning and co-director . of the University of California, Los Angeles Luskin Center for Innovation.

Lehmann has been working with Las Vegas city officials for the past six years developing a master plan for how to cool the city by 2050. In 2021, the city Clark County released its 2050 Master Plan, which contains plans to mitigate the heat. Planting low-maintenance and drought-tolerant plants to provide shade, reducing hard surfaces and designing buildings that provide shade are just some of the policies outlined. “But I believe we will see change,” says Lehmann, “now that the city wants it.”

Las Vegas has already started with other initiatives, such as opening public cooling stations for the homeless during heat waves and starting a planting project 60,000 trees by 2050 to provide shade. In the parking lot of a large basketball stadium, 1,000 parking spaces are being removed to plant 1,000 trees. Still, it’s a controversial move, Lehmann says, in a city so dependent on the car. The city is also working with engineers at the University of Vegas to develop a reflective roof coating for hundreds of Las Vegas casinos and hotels — but its application will be voluntary, Lehmann notes.

As always, it’s about implementing a multitude of solutions and thinking outside the box. Despite his disappointments, Lehmann remains positive. “As architects, our job is to reimagine the future,” he says. “I don’t need to see what Las Vegas looks like now, I need to see what it looks like in 20 years.”