If you ever You’ve felt the effects of an urban heat island, taken from the country to the city and amazed at the way the temperature has risen dramatically. Roads and buildings in a metropolis absorb the sun’s energy during the day and slowly release it at night. The built environment basically bakes itself, and temperatures can rise up to 20 degrees Fahrenheit higher than in neighboring countries, benefiting from the “sweat,” water vapor and the shaking of trees that cool the air.
As global temperatures rise rapidly, scientists, governments and activists are looking for ways to address the effects of the heat island. According to the World Health Organization, the number of people exposed to heatwaves increased by 125 million between 2000 and 2016. Extreme heat kills more Americans than any other natural disaster and is especially dangerous for people with previous conditions such as asthma.
By 2050, seven out of 10 people will live in cities, according to the World Bank. It would be a completely swollen man. “I really see cities as a kind of canary in a state of coal mining, where you have some harbinger of what the rest of the planet can feel,” said Vivek Shandas, a climate adaptation scientist at Portland State University. Has studied the effects of heat islands in more than 50 U.S. cities.
Shandas’s study found that even within the city, one neighborhood can be 15 degrees hotter than the other, and that inequality is a map of income inequality. One of the main predictions of heat in a neighborhood is how green space it is. The richer part of a city has more green, and the poorer part has more concrete; They are extensively developed, and filled with large box stores, freeways and industrial facilities that soak up the sun’s radiation. A concrete landscape is so good for retaining heat, in fact, it will stay warm all night. When the sun rises, a poor neighborhood is already hotter than a rich neighborhood.
Scientists have just begun studying how they can reduce the temperature of city structures by installing “cool” roofs, walls and sidewalks – which are light in color and bounce in sunlight. Light surfaces reflect more sun radiation than dark surfaces. (Think about how you feel when you wear black instead of white on a sunny day. This albedo effect is part of the reason why the Arctic warms up so fast.) Strangely complex.
Take the problem of cold roofs, says environmental engineer George Ban-Weiss, who studies cooling infrastructure at the University of Southern California. Theoretically, large, flat peaks of commercial buildings are easy to paint white or light gray. Residential homeowners can choose lighter tiles – regular old clay actually reflects sunlight very well. These changes will cool the air coming from the roof, as well as the structure itself, which means residents will not often need to run the air conditioner. If a building can support the extra weight, the owners can even create a roof garden filled with plants, which will cool the whole area by emitting water vapor.
But while these changes will make the lives of people inside each modified building more bearable, if adequate owners follow, it can be an unintended regional side effect in some areas. In a coastal metropolis like Los Angeles, urban warmth usually contrasts with the coolness of the ocean, which drives a reliable sea breeze. As the land and sea temperatures get closer to each other, the amount of that air may decrease. “So it means less clean air coming into the city, which will increase the concentration of pollutants even more,” Ban-Weiss said, as well as the loss of air that keeps people cool.