Maria Velez, 53, knows she is lucky to live next to a creek. A stone’s throw from her home, other neighborhoods with small apartment buildings are much more paved and much less green.
The perfect recipe for creating heat islands, recording much higher temperatures sometimes on just a few streets. A phenomenon that is becoming more and more dangerous because of global warming.
In the United States – where hurricanes, tornadoes and floods are however legion – the meteorological phenomenon that kills the most is none other than heat.
Nearly 600 volunteers had registered, 500 had to be refused. Those chosen could be compensated with a few tens of dollars, but more than 60% did not take the money.
This is why Maria Velez, concerned about the subject, chose to participate in a campaign aimed at mapping these heat islands in Montgomery County, where she lives, north of the American capital.
The initiative is headed by the American Agency for Oceanic and Atmospheric Observation (NOAA), which for six years has made it possible to study some 70 localities, with the help of their inhabitants.
A sensor in the passenger seat window
“I registered right away,” says this university professor. “I found that was exactly what the county needed to do, seek to better understand the effects of climate change.”
On her gray family car, she and her husband hung a sensor, a kind of small white antenna, on the window of the passenger seat. Once turned on, the device records the temperature, humidity, time and its exact position every second.
The couple was assigned a route of approximately 17 km, to be covered by not exceeding 55 km / h, and covering a large part of the city.
Within an hour, they return to their starting point, where county employees await them, who retrieve the sensor and note any difficulties encountered – in their case, a failed roundabout exit that led them to make the turn twice.
To thank them, “citizen scientist” T-shirts are distributed.
Influx of volunteers
In total, more than a hundred people took part in the experiment that day: 57 teams of two rode 19 different routes, covering more than 500 square kilometers of the county.
Temperature was measured along each route three times during the day: at 6 a.m., 3 p.m., and 7 p.m.
The program was a success that surprised even its organizers: nearly 600 inhabitants had registered to participate (500 had to be refused). Those chosen could be compensated with a few tens of dollars, but more than 60% did not take the money.
The sensors were then sent to the partner company, CAPA Strategies, which, within a few weeks, must analyze the data and transform it into detailed maps, indicating the hottest spots.
Today, the number of days above 32°C in Montgomery County is about 19 per year. In 2050, it will be 70 days
“It’s low-income people and people of color who tend to be the most affected,” said Gretchen Goldman, head of the White House Office for Science and Technology Policy, present for the occasion.
The red line of segregation
Studies have shown the impact that old discriminatory policies still have — such as “redlining,” which saw banks limit housing loans to residents of certain poor, black neighborhoods marked with a red line on maps , thereby reinforcing the segregation at work.
“These neighborhoods, even today, turn out to be warmer than the more white and wealthy ones,” says Ms. Goldman.
Adapting to increasingly extreme heat episodes, fueled by climate change, is becoming essential.
Today, the number of days above 32°C in Montgomery County is about 19 per year. In 2050, it will be 70 days, according to Ken Graham, director of the National Weather Center, which is part of NOAA.
Thanks to the mapping campaigns carried out in recent years, “parks have been built in certain neighborhoods, or changes have been made to the roofs: light roofs rather than dark ones”
Urban heat islands form because the sun’s heat is absorbed more by concrete, roads, buildings, than by grass or water, for example.
Planting trees is therefore essential, but other solutions are also being developed, such as ultra-reflective paints.
Thanks to the mapping campaigns carried out in recent years, “parks have been built in certain neighborhoods, or changes have been made to the roofs: light roofs rather than dark”, relates Ken Graham.