To mitigate the damaging effects of heat domes and the urban heat island effect, American cities are aggressively planting trees, painting sidewalks white, and reducing concrete surfaces.
In 2013, Los Angeles became the first major city to mandate cool roofs on all new homes. The city, which projects a dramatic increase in 95-degree days by 2050, has since employed other cooling initiatives, including painting sidewalks white and expanding the city's Green Building Code to require cool roofs on non-residential buildings, according to the BBC.
Despite these mitigation efforts, however, residents of the city continue to suffer from heat-related issues. A study found a direct correlation between the number of extreme heat-related emergency calls in Los Angeles from 2018 to 2022 and the number of days with temperatures at or above 90 degrees Fahrenheit.
Planting Trees
Trees cool the air and ground by providing shade, evaporative cooling, and transpiration. Studies have shown that urban forests are, on average, 1.6 degrees Celsius cooler than treeless neighborhoods.
Many cities across the U.S. are embracing tree-planting initiatives. Austin, Texas, aims to have 50% of the city covered by tree canopy by 2050. In Phoenix, Arizona, the hottest major city in the U.S., tree-planting efforts have brought shade to low-income neighborhoods. City officials approved more than $1.4 million to plant 1,800 trees throughout the city, providing much-needed cooling corridors.
White-Painting Roofs
A recent study discovered that white-painted roofs reflect up to 80% of the sun's light and are 29 degrees Fahrenheit cooler in the late afternoon. The concept is not new, with cities in North Africa and Southern Europe employing the practice for centuries. The solution is now gaining traction in the U.S. New York City has recently painted more than 1 million square feet of rooftops white, reducing indoor temperatures by 30%. The state of California has also updated its building codes to encourage cool roofs.
Additional Solutions
Extreme heat planning is also crucial for cities like Las Vegas. The city is the second-fastest warming in the U.S., after Reno, Nevada, reaching 115 degrees Fahrenheit in June. Experts have worked with city officials over the past six years to develop a plan to beat the heat by 2050. The heat mitigation plan includes planting low-cost, drought-tolerant trees for shade, reducing impervious surfaces, and designing buildings with overhangs.
Summary
Extreme heat events are an increasing threat to cities around the world. Heat domes and the urban heat island effect can lead to dangerous temperatures and health problems. Cities in the U.S. are taking a variety of measures to mitigate the effects of extreme heat, including planting trees, painting sidewalks white, and reducing concrete surfaces. These efforts can help to cool cities down and make them more livable.