Miami's built environment is leading to "heat islands"

Miami is tied with Chicago for having the third-worst "urban heat island effect" — increased temperatures from buildings and roads having replaced vegetation — of 44 large U.S. cities, according to nonprofit Climate Central.

Why it matters: Heat islands can make cities less livable and increase the risk of heat-related health complications, Axios' Alex Fitzpatrick reports.

• Heat islands can also lead to increased energy usage and costs as residents keep cool with air conditioning.
• And low-income neighborhoods tend to be more vulnerable to heat islands than wealthier ones, making this a key climate equity issue.

What's happening: In its 2023 Urban Heat Hot Spots report released last month, Climate Central calculated the urban heat island (UHI) index of census tracts within each city it analyzed.

• UHI index measures how much hotter certain areas are due to the built environment.
• The average UHI index across Miami is 8.3°F.
• In parts of the city where there are tall buildings and few trees — like Brickell and Edgewater — the UHI index is 12°F.

Details: Miami's high UHI index values are driven partly by albedo, the proportion of incoming sunlight reflected by a surface.

• Elements such as roads, buildings, parking lots and water bodies absorb sunlight and radiate it back into the city as heat, the report explains.

Zoom out: There are 41 million Americans living in urban areas where heat islands raise local temperatures by 8 degrees or more, per Climate Central's analysis.

• Wichita (7.2°F) had the lowest average UHI index per capita. New York (9.5°F) and San Francisco (8.8°F) were higher than Miami and Chicago.

What they're saying: "The biggest thing we can do is replace surfaces that absorb heat with surfaces that reflect heat," Kaitlyn Trudeau, a senior research associate at Climate Central, told the Miami Herald.

• White roofs, reflective pavements and more trees can all help.
• Officials aim to increase Miami-Dade's tree canopy from 20% to 30% by 2030.