Global South shows higher urban flood exposures than the Global North under current and future scenarios

Abstract

Urbanization has intensified in recent decades, raising concerns about increasing flood exposure in cities. Here, we assess urban flood exposure in terms of built-up area, population, and economic activity located within zones affected by 1-in-100-year river flood events. We use global historical data from 2000 to 2020 and future projections from 2030 to 2100 under the Shared Socioeconomic Pathways. From 2000 to 2020, global urban flood exposure increased substantially, with the most severe impacts in East Asia and the fastest growth in Africa. Future exposure continues to rise, especially under high-risk development scenarios. From 2030 to 2100, flood-exposed urban area, population, and economy in Global South are more than twice, nearly five times, and over twice those in Global North, respectively. Inequality in exposure is greater within developing regions than developed ones. These disparities are projected to widen, highlighting the urgent need for targeted, region-specific strategies to reduce flood risks. Urban flood exposure in terms of area, population, and economic assets has increased significantly from 2000 to 2020, particularly in East Asia and rapidly in Africa, with projections indicating continued and unequal growth, especially in the Global South, according to an assessment of 1-in-100-year river flood hazard maps.