Changing hazards, exposure, and vulnerability in the conterminous United States 2020–2070

Natural resource systems are being reshaped by changes in climate, resulting in increased likelihoods of wildfire, water scarcity, and heat stress, along with other adverse outcomes that define potential harm across a broad spectrum of locales in the United States. We evaluate fifty-year, multiple scenario projections of resource hazards and population change from the USDA Forest Service 2020 Resources Planning Act Assessment to identify areas of concern based on hazard exposure and social vulnerability criteria and evaluate implications for climate adaptation and risk mitigation planning. We project how and where hazard exposure may change over the next fifty years and decompose changes into the portion driven by climate and population—both prove consequential. Water shortage projections show little change in spatial distribution but strong growth in the intensity of anticipated shortages. Wildfire projections show a structural change in pattern with emergent growth in wildfire extent in the southeastern US coincident with higher population densities and social vulnerability. High heat areas expand toward the north and east from the Southwest. Projections also show substantial growth in areas affected by two or more hazards and highlight where hazards correspond with high exposure and/or high vulnerability. For all hazard categories and scenarios, at least 80% of the population exposed to high hazard is in either a high vulnerability or high exposure county. Results highlight how management strategies would differ between those focused on mitigating the biophysical hazard alone and those that focus on mitigating exposure or vulnerability criteria.