A couple of weeks ago, I wrote about the connections between pandemics and climate. The feedback I got was basically "hey, connecting the dots is really interesting but also this is specifically very terrifying. So maybe something similar but with less pandemic trauma?" I hear you. Also, this is what it's like in my brain every day.

But today we're going to talk about urban heat islands, why some places are so much hotter than others, and how this correlates to socioeconomic factors like income and race.

​Extreme heat is the leading cause of death in the summertime. Why? There are a variety of reasons, ranging from the heat itself (limited access to cooling centers or the ability to afford fans or air conditioning in lower income, unhoused, or elderly populations), but also exacerbation of pre-existing respiratory and cardiovascular conditions. Additionally, many outdoor or warehouse workers will be at risk of heatstroke in extreme heat conditions.

​Urban areas get really hot in the summer. They're densely populated. The constructed environment retains heat, and also blocks the natural breezes that might cross an unbuilt landscape. If you've spent any time in a desert city like Phoenix, Arizona, you'll know that asphalt and concrete from the built environment absorbs heat by day and radiates heat after sunset, long after the unrelenting sun has set. This means that the city and denser suburbs simply don't cool off at night. It's estimated that the urban areas are substantially hotter than their more rural counterparts. This is known as the urban heat island (UHI) effect.

The presence of green space — gardens, parks, trees — can dramatically reduce the temperature in a built area. For example, Columbia University researchers found that temperatures were substantially cooler around Central Park than in the Bronx.

Many of the hottest urban areas also happen to be inhabited by populations that tend to be poorer, and also communities of color. As it turns out, there are direct correlations between areas that were historically "redlined" and the hotter urban areas of today. (Redlining was the practice of denying financial services and investments to communities of color. While the practice was banned in the 1960s, the impacts live on.) One study showed that, "neighborhoods located in formerly redlined areas—that remain predominantly lower income and communities of color—are at present hotter than their non-redlined counterparts. Although the extent of differences in temperatures varies by region, the preponderance of evidence establishes that those experiencing the greatest exposure to present and potentially future extreme heat are living in neighborhoods with the least social and ecosystem services historically."

Treelined streets and parks tended to be placed in higher-income (historically white) neighborhoods. "Neighborhoods where most residents identify as people of color had access to an average of 43 percent less park acreage than predominantly white neighborhoods."

Research shows that you don't even need a Central Park-sized green space to make a difference. Even small city squares, rooftop gardens, or small public spaces can have a positive impact.

​Project Drawdown gets real about what we need to see some changes: "Maybe it’s time to acknowledge that despite the heroic efforts by many, international diplomacy and national policy leadership in this age of extreme polarization and powerful special interests aren’t getting the job done.... It’s time we have a more expansive vision of climate leadership, one that’s not overreliant on international diplomacy and federal policymaking. Indeed, those of us working in climate know that the most effective leadership often comes from grassroots communities, local and state governments, business leaders, technology innovators, engineers, investors, and philanthropists – not elected officials and diplomats."

​How do we effectively estimate excess mortality from extreme temperatures? "[With] no adaptation to heat, temperature-related mortality is expected to increase in response to climate change across scenarios and periods for most of Europe. For the selected 854 cities, this net effect could lead to a 50% increase in temperature-related death rates and a total cumulative death toll exceeding 2,000,000 toward the end of the century...."

​AI, wars, and climate change mean it's later than ever on the "Doomsday Clock." So that's uplifting.

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Consulting

​Reduce your Scope 3 emissions​

Alisa Bonsignore

Founder, Strategist, and Author