imagine two neighborhoods just three subway stops apart. one bakes at 96°f during a heatwave, while the other stays at a cooler 87°f. behind heat disparities like this, is the legacy of racial discrimination.

this podcast examines the stark realities of these temperature disparities, focusing on phenomenons such as urban heat islands, and real-life examples from washington, dc, where neighborhoods like park view and colonial village reveal the enduring effects of systemic inequality. insights from zoe davis, boston’s heat resilience leader, highlight the measures cities are implementing — tree-planting initiatives, cooling shelters, and other innovative solutions.

but is that enough? in a conversation that bridges history, science, and social justice, we ask ourselves: is it time to hold ourselves and our governments accountable — and to build a future where everyone can thrive?

podcast transcript:

mario castroviejo: imagine two neighborhoods, just four miles apart and separated only by three subway stops. during a heat wave, one reaches 96 fahrenheit degrees while the other stays at 87. ninety-six and 87.

they are only three metro stops away. it doesn’t seem real, does it? well, it is.

these neighborhoods are park view and colonial village in washington, d.c. and this disparity isn’t unique. cities like phoenix, boston, and miami experience similar patterns. and here’s the kicker: one of the main causes behind these temperature differences is racial discrimination. let’s break it down with some data. according to research by the atlantic council, black and hispanic workers experience at least 10 more days of extreme heat per year compared to white workers.

10 more days. that’s not just an uncomfortable statistic that is product of chance. it has everything to do with the environment in which people live and work.

it’s about how decades of discriminatory policies shaped the design of our cities, leaving lasting impacts. but today, some local governments are working to undo the damage. to understand how these disparities arose, i spoke with zoe davis, head of boston’s heat resilience team.

i asked her a basic but critical question. where do these disparities come from?

zoe davis: the homeowner’s loan corporation map. this is one of many tools that was used through the 30s and 40s to essentially evaluate the riskiness of providing loans to people who wanted to purchase land. and so this tool was essentially… it provided a series of grades.

this gradient was largely defined by race and heritage as well, socioeconomic background. and so there were whole areas where if there were people of color, if there were jewish people, then the grade of that particular area would be set lower. and so using those grades, essentially loan providers would be able to see, okay, is it perceived as too risky to provide these loans?

essentially what that did is that dictated where private investment was across the city.

mc: although the homeowner’s loan corporation or federal housing administration maps that rank neighborhoods from a to d or to f are no longer in use, their effects persist. during all those years, a-rated neighborhoods attracted more investment. they got better infrastructure, more green spaces and an abundance of trees.

meanwhile, the lowest rated neighborhoods were left with dense housing, minimal green space and underfunded infrastructure. let’s return to those washington dc neighborhoods as they work as a great example. we’ll start with colonial village.

it’s a picturesque tree-lined suburban area where most residents are white. every house has a garden and the area is close to a small river surrounded by greenery. here, it’s seven degrees fahrenheit cooler than the city’s average temperature.

those trees, they do more than beautify the landscape. they act as natural cooling system, deflecting solar radiation and releasing moisture into the air. contrast that with park view.

it’s located just north of howard, a historically black university. in here, things heat up, literally. the temperature is 8.5 degrees fahrenheit hotter than the average for washington dc. here, trees are sparse and the landscape is dominated by row homes tightly packed together, expansive parking lots, playground covered with dark surfaces and minimal green space. all of these features create a perfect storm for what scientists call the urban heat island effect.

zd: what we’re seeing today is areas that have experienced that historic disinvestment are experiencing much hotter conditions. now, some of that is due to the quality of the built environment. some of that is also due to how much sort of impervious structures and how much hardscape there is across the environment.

mc: here’s the science. paved surfaces and roofs, especially those painted with dark colors, absorb the sunlight and retain the heat, which combined with that released by technologies such as air conditioners, cars and industrial activity, creates an island warmer than surrounding areas. park view is a great example of this.

it’s covered with great structures that reduce airflow and absorb heat, such as three-story row homes stuck together tightly, basketball and tennis courts, a parking lot and playground structures with dark surfaces beneath them. meanwhile, in colonial village, the presence of trees and vegetation helps keep temperatures cool by deflecting solar radiation, providing shade and releasing moisture into the atmosphere. coupled with a lower concentration of buildings and concrete, all of this results in less heat retention.

so basically, the map outlined by some organizations 90 years ago has resulted in black and latino neighborhoods nowadays being hotter than white neighborhoods. and it’s not just a dc problem. this pattern repeats across the nation.

a recent study by the department of energy of over 400 american cities revealed that black residents live in air that’s 0.5 fahrenheit degrees warmer than their city average, while white residents enjoy air that’s 0.4 degrees cooler. think about that. living under hotter conditions every single day has very serious consequences.

extreme heat affects more than comfort. it’s a matter of survival. for residents and workers of neighborhoods like park view, the risks compound.

residents often commute long distances and wait for buses under the sun with no shade or tree coverage. many are low-income and can’t afford to run air conditioning continuously. homes are smaller, more crowded and trap heat.

and when a heat wave strikes, finding relief isn’t always an option. public cooling centers may be out of reach and health care access is often limited, exacerbating even more the health impacts of extreme heat. the problem is massive.

now fast forward to the year 2050. experts predict that summer highs will climb by 4.5 fahrenheit degrees in phoenix, by 4 in boston and by 5 in dc. for already hotter neighborhoods, the future looks even more severe.

but there is hope. cities like phoenix, boston and dc are stepping up, rolling out plans to become more heat resilient. and in boston, zoe davis is leading the charge.

zd: we have outlined our framework for preparing for hotter summers and preparing for extreme heat to be the norm. that means increasing access to cooling resources and cooling hot spaces. so that can be the built environment outside, indoor temperatures and also looking at ways to increase green infrastructure and tree canopy.

mc: in the short term, cities are implementing measures like distributing air conditioners and establishing cooling centers. however, zoe acknowledged the short sight of these efforts.

zd: one thing that we have heard from residents is generally people prefer to stay in their homes rather than go to a cooling center. or they might go somewhere else, but not necessarily because it is a cooling center. so what that means is we have a long way to go in terms of refocusing and really building out strategies that help to cool people, especially in our existing buildings.

mc: so while this short-term relief is crucial, it’s clear that the solution lies in long-term investments. one of those, trees.

zd: some of the ways that we’re looking at cooling are through tree planting initiatives. this is trying to reduce ambient temperatures around the building. this does have impacts on the building envelope and what people are experiencing inside.

it does take a bit for trees to essentially provide those bigger, longer-term benefits, but this does go towards the longer-term resilience of the area.

mc: however, trees take time to grow and a whole plan is needed to integrate them in the environment. but their impact is undeniable. they cool the air, reduce heat around buildings, and improve overall livability.

still, i wanted to know if beyond plans, they are actually carrying out any action right now. zoe shared an exciting project boston rolled out this past summer.

zd: we have implemented a living roof retrofit on 30 of our bus shelters across the 28 bus line. and so this is one of our free fare bus lines. it’s also one of the busiest bus lines in the city.

this is really making the case for building out shade in the public right-of-way.

mc: this project is just one example of how cities can improve. according to the boston mayor’s office, painting surfaces such as roads with reflective or light colors can lower the perceived temperature by one fahrenheit degrees, planting trees in clusters by eight degrees, and installing shaped canopies by 12 degrees. the cumulative impact of efforts like tree planting, creating climate shelters, and other projects such as the ones i’ve just mentioned can make a tangible difference.

but this isn’t just about cooling cities. the real goal is equity, to create livable, sustainable spaces for everyone, especially the communities that have historically been left behind. despite all these promising projects and initiatives having a great focus on neighborhoods historically discriminated against, the big question remains.

how do we redesign our cities to truly protect the most vulnerable among us? as citizens, we have the power and the responsibility to hold our governments accountable, to demand they confront the legacy of discrimination that continues to shape the environments we live in, and to push them to take meaningful action to undo the damage caused by decades of systemic neglect. this is about more than urban heat islands or temperature disparities.

it’s also about justice.