Analysis for Broward County, Florida | 2020
In Broward County, our analysis found that urban heat islands increase maximum temperatures by as much as 5°F above the local baseline. 90,000 people live in neighborhoods where the urban heat islands increase temperatures by 2°F or more and where average per capita incomes are less than 200% the federal poverty level. 33,000 people live in areas that meet the above criteria and have a high percentage of population in high risk age groups (under age 14 or over age 65). Every additional degree carries significant public health costs.
In the Broward County’s most severe urban heat islands, all-cause mortality rates are estimated to increase by 4.7% (2.4% - 7%) when baseline temperatures exceed 90°. Broward County experience 74 days above 88°F per year, on average. Our model estimates that 13 – 44 lives are lost in the county each year due to urban heat islands effect.
The public health burden of urban heat islands is disproportionately levied on the lowest income households. In Broward County there is a strong correlation between household income and urban heat islands (Table 1).
Without intervention, Broward County’s heat island impacts will grow significantly in a changing climate. Number of days above the 88°F threshold has increased by 36% since 2000 (Table 2). On the current trajectory Broward County will experience 144 days above the temperature threshold by 2050, and 223 days above the threshold by 2100.
“There is a strong correlation between summer heat and negative health outcomes. Temperatures above 82°F significantly increase the risk of cardiovascular diseases, respiratory illnesses, and heat stroke.”
*High Risk Area is defined as neighborhoods where the urban heat islands increase temperatures by 2°F or more and where average per capita incomes are less than 200% the federal poverty level.
**Highest Risk Area is defined as neighborhoods where High Risk Area criteria is met as well as a high percentage of population in high risk age groups (under age 14 or over age 65).
Wildish, J. 2020. Urban Heat Island Analysis: Broward County, Florida. Earth Economics. Tacoma, WA.
References
Department of Environmental Health, Harvard T.H. Chan School of Public Health. 2016. Study on the Association Between Ambient Temperature and Mortality Using Spatially Resolved Exposure Data.
Wang, Y., Akbari, H., 2016. The effects of street tree planting on Urban Heat Island Mitigation in Montreal. Sustainable Cities and Society 27, 122–128.
Huang, J., H. Akbari, and H. Taha. 1990. The Wind-Shielding and Shading Effects of Trees on Residential Heating and Cooling Requirements. ASHRAE Winter Meeting, American Society of Heating, Refrigerating and Air-Conditioning Engineers. Atlanta, Georgia.
Kurn, D., S. Bretz, B. Huang, and H. Akbari. 1994. The Potential for Reducing Urban Air Temperatures and Energy Consumption through Vegetative Cooling. ACEEE Summer Study on Energy Efficiency in Buildings, American Council for an Energy Efficient Economy. Pacific Grove, California.
U.S. Centers for Disease Control and Prevention (CDC), National Center for Environmental Health Project Number 4UE1EH001047-03. 2015. Health Effects of Summer Heat in Florida.