Unequal Impacts of Compound Precipitation Extremes on Global Transportation Infrastructures by the late 21st Century

In this study, we have unveiled the inequalities in threats from compound precipitation extremes (CPEs) on global transportation infrastructures by the late 21st century under various climate change scenarios. Approximate two-thirds of global transportation infrastructures will experience an increased exposure risk to CPEs under SSP585. Furthermore, a total length of 12.6 million km transportation infrastructures will likely encounter more frequent CPEs with at least a 25% decrease in joint return period. Notably, most of those infrastructures are located in the Global North, amounting to over 8 times the infrastructure found in the Global South (i.e., 10.9 versus 1.3 million km). Safety factor is proposed based on the most-likely CPEs in historical and future periods to adopt impact of CPEs, showing remarkable differences among countries of varying income levels. Under SSP585, the low-income countries require the highest safety factors (an average of 1.31) for the CPE with a 50-year joint return period (JRP), followed by lower-middle-income countries at 1.20, upper-middle-income countries at 1.17 and high-income countries at 1.15.