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A new study has revealed a stark and growing inequality in urban flood exposure across the globe, with developing nations facing risks that are multiples higher than their wealthier counterparts. The study warns that this gap is set to widen, posing a severe threat to sustainable development and highlighting an urgent need for equitable climate adaptation strategies.

The comprehensive analysis, in Communications Earth & Environment, was conducted by researchers from the Institute of Applied Ecology of the Chinese Academy of Sciences. The researchers systematically assessed the impact of 1-in-100-year river flood events on cities worldwide.

They found that between 2000 and 2020, global urban flood exposure—measured by the amount of built-up area, population, and economic activity at risk—increased substantially. East Asia was the most severely affected region, while Africa experienced the fastest growth in exposure.

Looking ahead, the study projects an alarming continued rise in these risks, especially under high-risk development models. The findings underscore a dramatic divide between the Global North (typically referring to industrialized nations in North America and Europe) and the Global South (developing countries in Africa, Asia, and Latin America).

By 2100, urban areas, populations, and economies exposed to flooding in developing countries are expected to be more than twice, nearly five times, and over twice as large as those in the Global North, respectively. This inequality was found to be even more pronounced within the developing regions themselves.

Unlike earlier studies that focused on a single factor such as land use or population, this analysis integrated three key metrics—built-up area, population, and economy—and considered the role of urban expansion. It further examined how disparities could evolve under different Shared Socioeconomic Pathways (SSPs), standard scenarios used to model global development futures.

The findings provide clear scientific evidence for policymakers, emphasizing that without targeted, region-specific strategies, the triple threat of climate change, rapid urbanization, and socioeconomic inequality will put the world's most vulnerable populations at even greater risk. The researchers argued that the results should inform more just and effective flood management, climate adaptation, and urban planning worldwide.