Benefits of Conserving/Increasing Urban Tree Cover: Impacts on Heat-Related Mortality
We developed a new process-based method for quantifying and valuing changes in heat-related fatalities associated with changes in urban tree cover. This was a collaboration with US Forest Service and partners in the i-Tree (suite of forestry benefits tools) consortium.
We applied this method to a case study in Baltimore City, Maryland and estimated health benefits for older populations who are vulnerable to extreme heat. We expanded the analysis to ten cities across the United States, investigating variations in results for different conditions. The study provides a flexible, updateable method that can be directly linked to climate scenarios and a foundation for a decision support tool (e.g., climate change module for i-Tree).
Quantify urban tree and impervious cover
Estimate reductions in air temperature
Estimate reduced heat-related mortality
Monetize mortality benefits
Factors driving varying impacts and associated policy implications:
Where are the impacts highest, when do they occur and who might be impacted the most?
Factors
Results
Policy implications
Demographic groups
Over half of reduced mortality is for the population over 65 years
Informs targeted actions for vulnerable populations
Across cities (varying climatic conditions)
Hotter, drier cities experience higher impacts
Implications for policy analysis needing extrapolations
Spatial variation
within cities
Distribution of changes in heat metrics and population counts (especially older /more vulnerable populations) matter within cities
Implications for environmental justice and equity
Across the
summer months
Hotter, drier months within the summer season have most impacts
Public health interventions need to be designed accordingly
Measures of
extreme heat
Cooler cities may show less impacts throughout an average season, but trees can make a difference during heat waves
Frequency of heat waves/ heat-related deaths are projected to increase in cooler cities