Global spread of local cyclone damages through urban trade networks

Geophysical hazards stress urban social, economic and political systems, but many studies focus on single locations over short periods. The manner in which a natural disaster propagates across cities globally through urban trade networks remains unexplored. Starting from a novel empirical baseline model for global production and trade, here we develop a dynamical model for the spread of individual cyclone impacts across the world's cities. We find that cities are vulnerable to economic harm even if they are geographically distant from the location of direct impacts of cyclones. These adverse secondary impacts are responsible for up to three-fourths of the effects of the largest storms and are generated primarily by cyclone exposure in North America and East Asia, in part because of the roles of these regions as principal purchasers and suppliers, respectively, of industrial materials. Vulnerability to adverse secondary impacts of cyclones is highest in cities that are strongly dependent on the global trade network but have relatively few suppliers. Our results suggest that, in addition to improvements in protective infrastructure, urban adaptation to storm damage and climate change might require modifications to trade network linkages. Hazards affect more than the area originally hit. This study finds cities distant from cyclones may still be vulnerable to secondary impacts through their trade networks.