Racial and economic inequality have always come with environmental inequality. The least powerful tend to be forced to live closest to our most dangerous waste products, from traffic pollution, to industrial or electronic waste. As the planet warms, there’s a new kind of environmental inequality, but rather than the things we’ve come to expect – poisoned air and water – we’re facing unequal distribution of temperature.

Equipped with heat sensors, this group of citizen scientists were participating in a groundbreaking study: the first ever street level assessment of heat in New York City. The goal was to find differences in neighborhoods – which communities were relatively cool? Which were sweltering hot? – and map the city’s heat inequality.

Joined by others in upper Manhattan and Harlem, the volunteers scanned temperatures along the streets with sensors attached to their cars and bikes. The results, presented to community members in January, showed a harsh reality of city living: the south Bronx was 8F (4.5C) hotter than the Upper West Side and Upper East Side, some of the city’s richest neighborhoods, just a few miles away.
“The variation in temperature is stark,” said principal investigator Liv Yoon. The data was analyzed by Climate Adaptation Planning and Analytics Strategies and is part of a nationwide heat-mapping initiative by Noaa. “The built environment really matters on how heat manifests and what people feel,” said Yoon.

The results mirror what residents and researchers have known and brought attention to for years: in cities like New York City,heat is distributed unequally – and people of color and low-income residents shoulder the highest burden of heat. Poor air quality, inadequate access to cooling and air conditioning further exacerbates the likelihood of heatstrokes and deaths from heat exposure. There are approximately 370 heat-related deaths in New York City on average each year, with the Bronx being especially vulnerable.

This is not a surprise. I’ve talked before about the various health benefits of living near greenery, and I think it’s no accident that wealthier parts of cities tend to have more trees, more parks, and more vegetation in general. As the temperature continues to rise, that inequality will increasingly become a matter of life and death.

Heat is especially severe for people with pre-existing conditions such as heart disease, and as higher night-time temperatures prevent people from recuperating overnight, it is also driving a rise in sleep-related mental health problems.

Some residents, who have been living in close proximity to sweltering asphalt and further away from parks and trees, may not be surprised by this.

“The thing is, we already knew where the hotter areas were,” said Yoon. “What we wanted to contribute is connecting the dots.”
Environmental advocates say the data, because of how granular it is, can help make the case that certain neighborhoods need better resources and access to green space.

“We have always gotten the brunt of the city’s pollution,” said Melissa Barber, researcher and co-founder of environmental justice group South Bronx Unite.

The difference in temperature between the south Bronx and the Upper West Side reflect a myriad of other environmental inequalities. There are five major highways that run through and around the south Bronx, including the hulking Cross Bronx Expressway, which contributes to the surrounding area’s noise and air pollution. Despite being bounded to the south by the Harlem River, the waterfront in the south Bronx is so developed that residents cannot readily access the blue space. Meanwhile, the Upper West Side sits between Central park and Riverside park, which looks out on to the Hudson River.

Asphalt roads and densely built buildings in cities trap heat. These urban pockets of heat can also overlap with other health disparities: the south Bronx has one of the highest asthma rates in the country. Residents here also live in housing that tends to trap heat, and where the median age of apartment buildings is nearly 90 years.

“These spaces are not only deprived because of the heat they’ve acquired, the existing infrastructure is failing as well,” said Satpal Kaur, an architect who volunteered in the heat-mapping survey.

Climate change is killing people right now, and it was entirely predicted that it would hit the poorest first and hardest. That very fact may well be part of why the richest among us felt comfortable ignoring the problem for their own benefit. As things continue to get hotter, and people continue to suffer and die because of it, remember this: We, as a species, have the resources to help. It does not have to be this way.