Effects of Urban Vegetation on Mitigating Exposure of Vulnerable Populations to Excessive Heat in Cleveland, Ohio

Hot weather is a threat to human health, especially in cities, where urban heat islands (UHIs) are elevating temperatures already on the rise from global climate change. Increased vegetation can help reduce temperatures and exposure to heat hazards. Here, an ensemble of geographically weighted regressions (GWR) on land surface temperature (LST) is conducted for May-October to estimate potential LST reductions from increased vegetation and to assess the effect of temperature reductions among vulnerable populations in Cleveland, Ohio. Possible tree canopy increases are applied to the results, and it is found that LST reductions can range from 6.4 degrees to 0.5 degrees C for May-October and are strongest from May to July. Potential LST reductions vary spatially according to possible canopy increases and are highest in suburban fringe neighborhoods and lower in downtown areas. Among populations at high heat-related health risks, the percentage of the population 65 years of age or older in Cleveland is negatively associated with LST, while percentages of Hispanics and those with low educational achievement are most positively associated with higher LST. The areas that have a high percentage of Hispanic also have the lowest potential temperature reductions from increased vegetation. Neighborhoods with the highest potential temperature reductions had the highest percentages of whites. Three subpopulations associated with high heat health risks are negatively correlated (African Americans and the elderly) or not correlated (persons living in poverty) with LST, and the relationships to LST reduction potential for all three are not statistically significant. Estimates of the effect of vegetation increases on LST can be used to target specific neighborhoods for UHI mitigation under possible and achievable policy-prescribed tree canopy scenarios in Cleveland.