The forecast called for sunny skies and highs in the low 80s — mild weather by New York City summer standards. The shaded walkways of Sakura Park in Manhattan’s Morningside Heights neighborhood were breezy. But on the same block, the afternoon sun was pouring down an exposed stretch of Riverside Road, radiating heat from the asphalt.
It is precisely this phenomenon that brought NASA remote sensing specialist Dr. Christian Brannon to the park on this midsummer day in late July, where he met about two dozen New Yorkers who had volunteered to drive neighborhoods in Manhattan and the Bronx, and record temperatures. as they went.
“We’re really feeling the urban heat island right now,” said Brannon, pulling the recording table into the shade.
This day of temperature mapping was part of a national effort by the National Oceanic and Atmospheric Administration to better understand urban heat islands: areas that make buildings denser, and lots of concrete and little tree cover make life hotter in summer. The advocacy group South Bronx Unite, as well as researchers from Columbia University’s Earth Institute, coordinated the Bronx and Manhattan branches of the project.
“The temperature we already know is 70 or 80, or maybe 90 degrees, we’ll feel several degrees higher,” said Dr Melissa Barber, founder of the South Bronx Unite and organizer of this mapping project.
Urban heat islands will become more and more dangerous as temperatures continue to rise around the world, and new residents flock to cities. A global study published this month of 13,000 urban areas found that city dwellers’ exposure to life-threatening heat and humidity has tripled since the 1980s. This change has been due to urban population growth that has put more people in the crosshairs of rising temperatures. The New York City Commission on Climate Change predicts that by 2050, the city will experience twice as many days in excess of 90 degrees Fahrenheit as it did in the 1920s.
This year’s hot summer sent nearly 650 people to emergency rooms in New York City, more than the average death toll in the previous four summers. According to a 2017 report by Mayor Bill de Blasio’s office, extreme heat kills more New Yorkers than any other type of extreme weather. But it affects some neighborhoods more than others.
Studies show that neighborhoods and slums with more people of color experience higher summer temperatures. The reason for this is because these places tend to be densely built – with lots of asphalt and few shade trees, Barber says.
“We have been neglected in terms of many structures and infrastructures that have to be in place for some kind of heat insulating,” she said.
These differences can be dangerous for people exposed to extreme heat such as children, the elderly, and people who work outside. A city report found that heat stress killed an average of 10 New Yorkers each year between 2010 and 2019.
“People in areas that are more exposed to heat risks are also less likely to get healthcare,” said Dr. Lev Yun, co-organizer and postdoctoral researcher at the Earth Institute. “This is not a coincidence.”
Working in pairs, temperature mappers drove pre-planned routes through the city with white plastic temperature sensors hung from their commuter windows. Sensors fire every second, capturing differences in heat and humidity.
Some volunteers heard about the project through climate advocacy groups; Others were pulled by family members. At least two were former taxi drivers, who put their deep knowledge of the streets to use in a new way. All of them had firsthand experience with the brutal New York City summer.
“I come from Africa, so I expected it,” Fatou Diop, one of the volunteers, said of the heat as she drove through midday traffic with a sensor peeking out of her car window. “But it was so hot, I said, ‘What is this?'” “
“Sometimes here in Harlem, it’s like stagnant air,” added co-pilot Liz MacMillan, who has been guiding Diop through the twists and turns of the pre-planned course. “You get all this heat off the concrete. All the heat comes from the ground. All the heat bounces off the buildings.”
Project organizers say they will analyze the results and publish the maps online. Scientists like Braneon will overlay it with other data to better understand how infrastructure affects our experience with heat.
The South Bronx Unite and other groups can use these maps to advocate for heat-breaking infrastructure projects such as parks, accessible waterfronts, and cooling centers—particularly in neglected areas populated mostly by residents of color.
“If we use some of this data, we can reinforce the idea that we can also enjoy things like the waterfront,” Barber said. “We, too, can enjoy things like greenery. So, if that could be one of the ways we start moving forward with the stock idea, let’s do it.”