The recent concurrence of electrical grid failure events in time with extreme temperatures is compounding the population health risks of extreme weather episodes. Here, we combine simulated heat exposure data during historical heat wave events in three large U.S. cities to assess the degree to which heat-related mortality and morbidity change in response to a concurrent electrical grid failure event. We develop a novel approach to estimating individually experienced temperature to approximate how personal-level heat exposure changes on an hourly basis, accounting for both outdoor and building-interior exposures. We find the concurrence of a multi day blackout event with heat wave conditions to more than double the estimated rate of heat-related mortality across all three cities, and to require medical attention for between 3% (Atlanta) and more than 50% (Phoenix) of the total urban population in present and future time periods. Our results highlight the need for enhanced electrical grid resilience and support a more spatially expansive use of tree canopy and high albedo roofing materials to lessen heat exposures during compound climate and infrastructure failure events.

David Hondula (School of Geographical Sciences and Urban Planning, Arizona State University), Marie S. O’Neill (School of Geographical Sciences and Urban Planning, Arizona State University), Mayuri Rajput (School of Architecture, Georgia Institute of Technology), Santiago Grijalva (School of Electrical and Computing Engineering, Georgia Institute of Technology), Kevin Lanza (University of Texas Health Science Center at Houston School of Public Health), Sharon Harlan (Department of Health Sciences, Northeastern University and School of Human Evolution and Social Change, Arizona State University), Larissa Larsen (Taubman College of Architecture and Urban Planning, University of Michigan), Godfried Augenbroe (School of Architecture, Georgia Institute of Technology), E. Scott Krayenhoff (School of Environmental Sciences, University of Guelph), Ashley Broadbent (School of Geographical Sciences and Urban Planning, Arizona State University), Matei Georgescu (School of Geographical Sciences and Urban Planning, Arizona State University)