Exposure of Global Rail and Road Infrastructures in Future Record-Breaking Climate Extremes

Transport infrastructures built on historical experience are expected to face multiple threats under climate change, especially the continuous interruptive losses and additional maintenance costs caused by more intense or frequent record-breaking extreme climate events. In this study, we investigated the change in the exposure of global rail and road infrastructures to eight record-breaking meteorological hazards using the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) climate data, including extreme temperature and extreme precipitation. Our findings suggest that higher extreme heat and increasing thaw-freezing index ratio pose great threats to global rail and road infrastructures. The expected annual exposures of these two hazards are 4 and 2 times the average exposure level of eight hazards, respectively. Moreover, the exposure rapidly increases due to sharply increasing drought and heavy rain compound events as emissions growth and development accelerate, rising from 7% to 18% in eight hazard exposures. Sustainable and lower radiative forcing pathways would contribute to the exposure mitigation, with the peak exposure of eight hazards under the SSP2-4.5 and SSP1-2.6 scenarios averaging 29% and 52% lower, respectively, than that under the SSP3-7.0, which is an extreme scenario we may be on track for under current global efforts. However, the fact that most areas will still be affected by multiple hazards is probably unavoidable. Thus, in parallel with global efforts to reduce greenhouse gas emissions, we recommend that the transport sector incorporate locally appropriate climate change adaptation strategies to avoid losses induced by record-breaking extreme climate events. Transport infrastructure has a notably long service life. Nevertheless, infrastructure designed based on historical experience may be vulnerable to record-breaking extreme weather events. It should be noted, however, that different regions are likely to face distinct types of challenges. In this study, we investigated the probability of record-breaking climate extremes associated with eight types of hazards that have direct implications for transportation infrastructure, and we identified the primary challenges confronting railways and highways in diverse regions throughout the world. Our findings indicated that global extreme heat and permafrost thawing pose particularly severe threats. Furthermore, there is an increased risk of heavy rain events occurring in dry months, especially in the late-21st century under the scenarios of rapid development and high radiative forcing, and more infrastructure is expected to be impacted. We also showed that it is possible to reduce the exposure of global infrastructures by 29%-52% by pursuing more sustainable and lower radiative forcing development pathways. However, the fact that most areas will still be affected by multiple hazards is probably unavoidable. In addition to the existing global climate adaptation actions, the transportation infrastructure sector should also develop appropriate local climate change adaptation strategies to mitigate additional losses. Globally, future exposure to record-breaking extreme temperature is higher than that to record-breaking extreme precipitation, especially extreme heatGlobal rail and road infrastructures will be exposed to more frequent drought and heavy rain compound events, which were less noticed beforeRapidly developing and high-emission scenarios will lead to rapid non-linear exposure increases in the mid-to-late 21st century