Heat and Health in a Changing Climate: Building a Decision Support Tool for California Public Health Officials

The devastating effects of rising temperatures on human lives and livelihoods will worsen even the most conservative climate change scenarios. Despite advances in our understanding of how climate change will influence heat vulnerability, resources for decision-making are still lacking. While local forecast data and global extreme weather projections continue to improve, stakeholders are asking for decision-support about interoperability and appropriate interventions to reduce heat-health risks long term. The aim of our research was three-fold: (1) develop local heat health event thresholds, which can also serve as a baseline for climate projections and adaptation planning, (2) map heat-specific social and environmental variables, and (3), develop an interactive, user-friendly tool that enables users to access and compare these data layers. The result of this work is the California Heat Assessment Tool (CHAT, www.427mt.com/cal-heat/), as a part of California’s Fourth Climate Assessment. Medical and historical meteorological data form the basis for defining thresholds for heat health events that are locally specific. This tool uses those thresholds and climate projections for census tracts in California to inform how these specific heat health events are expected to worsen under climate change. Specific thresholds were developed for the general population and for frontline communities in California, with heat health impacts found at temperatures up to 4-5 degrees lower for those vulnerable populations. In addition to hotter temperatures, heat health events are projected to happen more frequently and last longer in duration and increasingly warm nights will exacerbate the health impacts, particularly for frontline communities. Climate projections are overlaid with socioeconomic and built environment data to help inform targeted service and public education delivery, promote climate adaptation efforts, and work with land use planners to inform cooling strategies.