Nearly three in four New Orleans residents likely live in so-called “urban heat islands” where the local temperatures are at least eight degrees higher than less-developed areas, according to new modeling released Wednesday.
In its report, nonpartisan science news nonprofit Climate Central found that out of 44 of the country’s largest cities, New Orleans is one of just five where more than 70% of residents live in areas that are estimated to be at least eight degrees hotter due to the city’s environment. The group’s analysis found 74% of New Orleans reaches that threshold — the third-highest proportion in the U.S.
The same abundance of dark asphalt and concrete that contribute to the city’s flooding also absorbs and retains the sun’s rays, then slowly radiates that heat back into the air. This creates “heat islands,” keeping the air hotter for longer periods in some spots and exacerbating the extreme heat that affects broader regions and has grown worse due to human-caused climate change.
In 2021, Climate Central issued its first national urban heat island report which found New Orleans suffered from the worst heat island effect in the country, beating out larger cities like New York and Houston.
Lafayette ranked 19th in the 2021 analysis, but isn’t included in this year's report, which estimated the intensity of the heat island effect at the census tract level in cities with larger populations. Other major Louisiana cities like Baton Rouge, Shreveport and Lake Charles were also left out.
The group’s model estimated the intensity of the urban heat island effect based on the prevalence of different types of land cover and built features within each census tract. It considered factors like how densely the area was covered with trees versus pavement or soil and whether buildings were tall and tightly-spaced or short and sparse with green space.
Julia Kumari Drapkin, whose climate technology for profit iSeeChange has studied extreme heat in Louisiana for years, said the findings came as no surprise.
“It's really important for us as a city to prioritize as a fundamental risk that many of us are living in urban heat conditions,” she said.
But Climate Central’s report was broad, Drapkin said, taking a “one-size-fits-all” approach to its analysis, and satellite imagery isn't always accurate when measuring albedo — the proportion of light, reflective surfaces. To address the underlying causes, like New Orleans’ severe deforestation problem, she said the city will need to rely on more localized data to guide solutions.
“We need to take a finer tool and a much more granular perspective,” she said. “You need a scalpel in every city that you're working in … when it comes to keeping people safe during extreme events.”
An analysis conducted by her team in 2020 found some areas of the city run up to 18 degrees hotter than other parts during the afternoon. The team spent months driving through the city with heat sensors.
They found that Hollygrove, Tulane Avenue, Dwyer Canal, Central City, Xavier University, Arabi and Algiers close to the West Bank Expressway were all extreme hotspots. Climate Central’s recent analysis also pointed to the Iberville neighborhood, the Central Business District and parts of Little Woods in New Orleans East.
This summer, Drapkin’s team is working with John Hopkins University to measure indoor heat within New Orleans homes, which are often old and poorly-insulated.
More specific studies can take into account the needs of each community when it comes to solutions like tree plantings or new housing cooling standards for landlords, Drapkin said.
Climate Central’s report also recommends measures like swapping out dark-colored pavement for lighter surfaces that absorb less heat and building with more reflective materials to keep heat out. Girard, the group’s communications director, added that one of the most critical solutions to limit worsening heat is to reduce greenhouse gas emissions which fuel climate change.
“Even if you protect people from the worst effects of urban heat islands, we’re still living in a warming world, and ultimately the only way to really cool down these neighborhoods in a way that is meaningful and long-term is to address climate change,” he said.
