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Urban Heat Vulnerability Mapping and Green Infrastructure Planning

Solution Overview

Through continued technical assistance provided by Earth Economics and the Urban Green Infrastructure Lab, preliminary urban heat mapping and a high-level analysis of vulnerabilities were completed for Broward County.[1][2][4] This approach identified communities experiencing elevated temperatures due to urban heat island effects and assessed the populations most vulnerable to heat-related health impacts. The heat vulnerability mapping information has been summarized in a brochure for distribution and served as the basis for grant applications to support development of heat mitigation strategies inclusive of green infrastructure.[4]

Technical Components

Earth Economics conducted an Urban Heat Island Analysis for Broward County, Florida.[1] The heat vulnerability mapping identified communities where there is both an increase of 2 degrees Fahrenheit or more of urban heat island, as well as average per capita incomes less than 200% the federal poverty level.[3] The highest risk areas identified in Broward County's heat mapping meet criteria of 2°F+ urban heat island increase, income less than 200% federal poverty level, plus have a high percentage of population younger than 14 and older than 65.[3] The model estimated that 13 to 44 lives are lost in the County annually due to excessive heat.[5] Analysis in Broward County indicates that the areas with the highest average summer temperatures and the communities most vulnerable to these temperatures are concentrated in eastern Broward surrounding major highways such as the I-95 and I-595.[3]

Implementation Details

The preliminary urban heat mapping and vulnerability analysis were completed through continued technical assistance provided by Earth Economics and the Urban Green Infrastructure Lab.[1][5] The analysis revealed that in Broward County, an Earth Economics study found that urban heat islands increase maximum temperatures by as much as 5°F above the local baseline.[2] Broward is exploring the potential to develop a network of temperature and humidity sensors that would trigger localized alerts upon reaching heat watch and warning advisory thresholds.[3]

Benefits and Impacts

The mapping initiative identified that 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.[2] The public health burden of urban heat islands was confirmed to be disproportionately levied on the lowest income households, with approximately 90,000 residents with income significantly below the poverty level living in neighborhoods where temperatures are higher than the rest of the county.[4][5] One third of the 90,000 low-income residents in high-temperature neighborhoods are at higher risk to heat health impacts due to their age.[4] Specifically, 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).[2] The model estimated that 13 to 44 lives are lost in Broward County annually due to urban heat island effects.[4] 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°.[2]

Climate Adaptation Relevance

In Broward County, the average temperature in 2021 was 3.7 degrees Fahrenheit warmer than it was in 1921.[3] The number of days above 88°F has increased 36% since 2000, to 90 days per year, with projections suggesting 144 days per year by 2050.[5] Broward County's heat map outlines the types of heat risk reduction strategies it is advancing – from stronger building codes to green infrastructure to cooling centers.[3]

Business Analysis

The heat vulnerability mapping information served as the basis for grant applications to support development of heat mitigation strategies inclusive of green infrastructure.[4] The analysis provided critical data to support policy and investment decisions targeting the approximately 90,000 residents with income significantly below the poverty level living in neighborhoods where temperatures are higher than the rest of the county.[4][5] Broward County's heat map outlines multiple heat risk reduction strategies it is advancing, including stronger building codes, green infrastructure, and cooling centers.[3]

Sources