1.9 billion people will face flooding by 2100: Study

Climate change and population growth are driving a global flood crisis; low-income regions at greatest risk, finds study

Flooding has become one of the most common and destructive natural disasters. In recent years, its intensity has increased primarily because of climate change, population growth and haphazard infrastructural development, especially in urban pockets. The global risk of flooding as a result of these factors is predicted to rise exponentially by the end of the century, according to a new study published in Nature Communications titled “The Role of Climate and Population Change in Global Flood Exposure and Vulnerability”. The study provides a comprehensive analysis of how climate change and population growth will shape flood risk by 2100.

The growing exposure to flooding

Researchers used a high-resolution global flood model for their analysis. This model accounts for coastal, fluvial (river), and pluvial (rainfall-driven) flooding. According to the study, by 2100, those exposed to a 1% annual risk flood event (100-year flood) will rise from 1.6 billion to 1.9 billion people. This increase in exposure is primarily driven by population growth (76.8%), with climate change contributing 21.1%, and a small 2.1% due to the interaction of both factors.

Climate change and flooding patterns

Climate change affects flooding through rising sea levels, increased rainfall intensity, and altered river flow patterns. The study finds that while global land exposure to 100-year flood events will rise slightly (from 11.1% to 11.4% by 2100), coastal flooding will see the most significant increase (16.7%), followed by pluvial flooding (4.8%) and fluvial flooding (1.4%).

Coastal regions, particularly those in low-lying tropical and subtropical areas, will be the hardest hit due to sea-level rise and storm surge amplification. Meanwhile, pluvial flooding—often associated with extreme localised rainfall—will become more frequent, even in areas experiencing a general drying trend due to climate change. Fluvial flood exposure will be highly variable, with some regions experiencing increased risk and others seeing reduced risk due to shifting precipitation patterns.

Disproportionate impact on low-GDP regions

A major highlight of the study is the inequitable distribution of flood risk. By 2100, low-income regions will account for 63% of total global flood exposure. This means that the populations least equipped to handle floods—due to inadequate infrastructure, weak governance, and lack of financial resources—will face the highest risks.

The analysis also reveals that urban areas will bear the brunt of rising flood exposure and cities in sub-Saharan Africa, South Asia, and the Middle East are expected to see the highest growth in flood-exposed populations. This underscores the urgent need for sustainable urban planning and improved flood defense mechanisms in vulnerable regions.

Flooding will pose a growing global threat in the coming decades, with both climate change and population growth contributing significantly to increased exposure. However, while climate change remains an important driver, population growth in flood-prone areas is the dominant factor behind rising flood risks. Addressing this challenge requires a multifaceted approach, combining climate mitigation, infrastructure development, and urban planning to ensure that vulnerable populations are protected from future flood disasters.

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