Toward a Climatic Risk Index for Public Health: Assessing Spatial Variability of Hazards and Vulnerabilities Associated with Climate Change

The U.S. Global Change Research Program (USGCRP 2016) has identified several mechanisms by which climate change is thought to affect human health, including through temperature stressors, air quality degradation, and exposure to extreme weather events. Concurrently, a growing body of literature demonstrates that vulnerability to these climatic hazards differs across populations with respect to markers of socioeconomic means, health status, and resilience. Despite recognition that climatic hazards may occur in concert and disproportionately affect the most vulnerable individuals, most health studies to date have assessed the effects of individual hazards, rather than considering the cumulative effect of exposure to multiple climatic hazards in the context of discrete vulnerability functions. Decision-makers at the local, state, and national levels tasked with protecting public health from the effects of climate change are consequently challenged by a lack of clear and consistent metrics for determining which areas and populations are most at risk of experiencing health effects from a variety of present-day and future climatic hazards. We present preliminary work toward the development of a climatic risk index to quantify and map spatial patterns of cumulative health risks from multiple hazards and community-level markers of vulnerability. Using daily temperature and precipitation data from the PRISM Climate Group’s 4-kilometer gridded climate dataset, Census-tract daily ozone (O₃) and fine particulate matter (PM_2.5) concentrations from EPA’s Fused Air Quality Surface Using Downscaling (FAQSD) model, and Census-tract metrics of vulnerability included in CDC’s Social Vulnerability Index, we show that climatic hazards and vulnerabilities exhibit substantial overlap, resulting in spatial variability of climatic risk both within and between cities and towns in the case-study New England region. The methodology presented here serves as a proof-of-concept for spatially assessing and visualizing multiple hazards and vulnerabilities to climate change, and is applicable not only to researchers of risk assessment and epidemiology, but also to urban planners, public health practitioners, and other decision-makers who are interested in systems-oriented assessments of climate change impacts.