This story was originally published by the guardian and appears here as part of the Climate Table collaboration.
The sweltering heat endured by major American cities is being driven by vast swaths of concrete and a lack of greenery that can increase temperatures by nearly 9 F (5 C) compared to surrounding rural areas, according to new research.
Last month, Phoenix experienced a four-day series above 115 F (46 C) for the first time and Boston hit 100 F for the first time in a decade. A deadly heat wave in the Northwest US, scientists say It would have been “virtually impossible” without human-induced climate change, Seattle warmed to a record 108 F, while Portland, where roads bent and power lines melted in the heat, reached an incredible new high. by 116 F.
The intensifying heat is accentuated in large urban areas by design, according to a new report which has attempted to quantify where the “urban heat island” effect is most acute.
By applying an index based on land use, amount of reflective surface, population density, and other factors, researchers have determined that out of 158 US cities. New Orleans it has the greatest heat disparity with its immediate surroundings – an average of 8.9 F warmer.
Newark, NJ, has the second largest heat island effect, averaging 7.7 F hotter than its surroundings, while New York City is 7.6 F hotter. Houston is fourth on the list, followed by San Francisco.
Cities are often hotter than the nearby countryside because they generate heat through transportation, machinery, and air conditioning that funnels hot air into the streets. The lack of trees, grass, and other plants, which help cool the air, is compounded by the prevalence of miles of hard, dark pavement and heat-absorbing buildings.
Central Climate, the nonprofit organization that conducted the researchHe said that tall, compact buildings, found in cities like New York, Chicago and Detroit, also increase the intensity of the heat.
“Certain cities are expected to score high, but there are also places like Burlington, Vermont, that were surprisingly high on the index,” said Andrew Pershing, climate science director at Climate Central.
“It shows that any city or town can get much warmer simply by the color of its pavement or some other factor. There is a lot of concern about the heat this summer, we are experiencing it in a way that surprises many of us, and this study shows us that there are things that we must start to change. “
Of 158 US cities, New Orleans has the largest heat disparity with its immediate surroundings – an average of nearly 5 C warmer, according to a recent report on the urban heat island effect.
Pershing said New Orleans’ highest ranking is due to the city’s age, a large number of dark streets, and sparse roof surfaces and green space, although the overall city average hides localized differences. “If you go to a parking lot, it will be much hotter than if you go to one of the famous cemeteries in New Orleans,” he said. “There is a lot of variability.”
Much of this variability can be traced back to racist housing practices, which concentrated people of color in neighborhoods. lacks cooling green spaces and tree shade. On a hot day, a neighborhood with little shade can be up to 20 F warmer than a more prosperous and green part of the same city.
Excess heat is the leading cause of death among weather-related factors and a growing alliance of public health, construction and weather groups called Smart Surfaces Coalitionon Wednesday called for an urban rethink that would install heat-reflective surfaces, solar panels and green roofs.
“Extreme heat in urban communities like Baltimore imposes huge health and financial costs, including rising heat-related deaths,” said Georges Benjamin, former Maryland health secretary and current executive director of the American Public Health Association. Benjamin said the changes will help address “the devastating impacts of climate change and achieve a fresher and healthier city.”
Pershing said cities must seek “creative and orderly solutions” to buffer the heat. “The heat is not going to get better. This is going to be a growing problem that cities will have to face over and over again, ”he added.