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The writer is a contributing columnist, based in Chicago
In the US, one of the most racially divided countries on earth, even heat discriminates.
Many non-white, poorer parts of US cities are simply hotter than white neighbourhoods — and that’s partly because they were designed to be unequal. In my (mostly white, affluent) neighbourhood near Chicago, the tree canopy is twice that of historically segregated (and still mostly non-white) areas only a few blocks away.
Fewer trees mean more heat, and that means more illness, according to the US Environmental Protection Agency, which calls such areas “heat islands”. They have more buildings, parking lots and roads, which absorb more heat in the day and radiate more at night than shaded areas.
“Heat is the silent killer, it is the number one weather-related cause of death [in the US] — not tornadoes or hurricanes,” Kyra Woods, adviser in Chicago’s Office of Climate and Environmental Equity, tells me. She is part of a team leading Chicago’s project to create a “heat map” of the city this summer, to find out which areas suffer the most.
Chicago may be more famous for bitter cold and wind than heat, but in a five-day period in 1995 over 700 people died here in a heatwave. Woods says “the impacts were not felt equally” by all. That’s partly because of “redlining” — a form of residential segregation in which non-white areas were labelled as undesirable for real estate investment. One study of 108 US urban areas found that formerly redlined neighbourhoods had surface temperatures about 2.6C, or nearly 5F hotter than others. “This is one of the most visible ways that we can see structurally racist decisions from the past play out today as climate risk,” says Max Cawley, who participated in a “heat mapping” project of Raleigh and Durham, North Carolina.
The Chicago Tribune recently published its own heat map of the city, which found that more than 300,000 Chicagoans live in areas that are hotter than 90 per cent of the rest of the city, or an estimated 5F to 10F warmer than the city average. Latino areas suffer the most.
Things are likely to get worse, Elena Grossman of the University of Illinois at Chicago School of Public Health, told me. “If nothing is done we will see more Chicago heatwaves that kill as many people as in 1995.” They will be “more frequent and intense”.
Dulce Garduno will be measuring heat in her majority Hispanic neighbourhood. She tells me the heat map is the first step to figuring out how many trees are needed in Chicago’s Pilsen, where she lives: “They covered all of Pilsen with concrete because they didn’t think about how important it is to have trees,” she says.
“Tree equity” for rich and poor, white and non-white areas is a goal of several big US cities, but there are other tools to tackle heat islands, including installing “green roofs” or “cool” roofs or roads, coated with reflective substances. Los Angeles has installed 181 miles of “cool” road surface, cutting temperatures by up to 8F, Ana Tabuena-Ruddy, chief sustainability officer of StreetsLA (the city’s streets department), tells me.
“We’re just barely scratching the surface” of LA’s 23,000 lane-miles of road, she says. Testing how much this can help reduce “heat islands” will take time. There are also structural impediments left from redlining, she says, including areas where the sidewalks are too narrow for trees.
But cities must watch for unintended consequences of measures, she warns. A study of “cool pavements [roads]” in Phoenix found that they increased temperatures for pedestrians by an average 5.5F at the hottest times of the day, because they reflected heat back at them.
Cities need to act now, says Morgan Zabow, heat and health information co-ordinator for the US National Oceanic and Atmospheric Administration, which spearheads the heat-mapping project. Chicago is projected to have 51 days above 90F by 2050 compared with 15 such days historically, she tells me, adding “and we know that brings an increase in heat-related illness and death”.
The challenge will be not just to prepare for future heatwaves — but to make sure we all have an equal chance to survive them.
