Program on the Environment

Extreme heat is the leading weather-related cause of death in the United States, and its burden falls disproportionately on communities with the least tree canopy. These neighborhoods tend to be shaped by histories of redlining and disinvestment, where temperatures can be up to 14°F higher than other neighborhoods on the same afternoon. This capstone aimed to assess the extent to which King County’s policy framework integrates urban tree canopy, extreme heat mitigation, and health equity, and to identify gaps that limit coordinated action across planning sectors. Through an internship with Public Health – Seattle & King County and the Department of Natural Resources, I reviewed and analyzed regional planning documents, best practices in urban forestry, and leading policy frameworks. Results indicate that while King County demonstrates strong cross-document commitments to climate resilience and equity, tree canopy is consistently siloed within climate and environmental policy and is absent from the land use, housing, transportation, and development standards where placement decisions are actually made. Six structural gaps were identified, including the absence of placement-sensitive development mandates, commitments lacking binding geographic targets, and fragmented policy across policy documents. With an upcoming planning cycle approaching, King County has an opportunity to embed enforceable, cross-sector canopy requirements and shift its governing question from how many trees can be planted to how trees must be placed for their benefits to reach the people who need them most.