Executive summary

Flooding is the most economically consequential natural disaster worldwide, responsible for more than 86% of weather-related damages since 1980. Annual flood damages have risen more than tenfold, from $11.2 billion in 1980 to $125.8 billion in 2023. As of 2025, the First Street Global Flood Model (FS-GFM) estimates that 1.92 billion people, or 23.3% of the global population, are exposed to at least 10 cm of flooding in a 1-in-100-year event. Under a moderate climate scenario, exposure is projected to increase by nearly 6% by 2100 with a constant population, or by almost 13% to 2.16 billion people when accounting for demographic change. These findings reveal that flood risk is both widespread and underestimated, underscoring the urgent need for physics-based tools to support resilience decisions.

10 key takeaways

The report identifies that weather-related disasters have caused over $5.1 trillion in global losses since 1980, with over $4.4 trillion attributable to flood hazards. Flood losses are accelerating faster than economic growth, with an average growth rate of 5.8% per year. Approximately $18.8 trillion in economic activity, or about 16% of worldwide production, is located in areas exposed to substantial flood risk. One in four people already faces substantial risk, with communities facing a nearly 10% chance of experiencing such flooding over a typical 10-year period. Risk is heavily concentrated in the Asia-Pacific and MENA regions, while Sub-Saharan Africa and Latin America are seeing the fastest growth in exposure.

Global trends in flood damages

The scale and pace of losses are increasing, reflecting both the severity of climate hazards and the rising value of assets in high-risk locations. Nearly 30% of the global population lives in coastal regions, a proportion growing faster than inland populations. These communities face compounding risks from sea-level rise, storm surges, and intensifying tropical cyclones. Additionally, more than 50% of the world’s population lives within 3 km of a freshwater body. Extreme rainfall events have increased by roughly 30% since the 1980s, driving a rapid rise in pluvial flooding even in historically arid regions like the United Arab Emirates.

Global mitigation frameworks: national backstops and flood insurance

Countries have adopted varied national programmes to manage flood risk, ranging from compulsory multi-peril insurance in Northern Europe to the National Flood Insurance Programme (NFIP) in the US. Some nations, like the Netherlands, prioritise state-led flood defences and protective infrastructure over household insurance mandates. In many low- and middle-income countries, insurance penetration remains limited, leaving vulnerable households to depend on post-disaster aid or sovereign risk pools like the African Risk Capacity (ARC). A fundamental challenge persists across all regions: a lack of property-specific information, which often leads decision-makers to underestimate the probability and severity of flood events.

First Street Global Flood Model

The FS-GFM represents the first global deployment of the HEC-RAS 2D hydraulic solver, operating at a 30-metre global resolution. Unlike many global models that rely on simplified hydraulic assumptions, HEC-RAS directly solves the physics of water movement using shallow-water equations. This enables more realistic representations of river overflows, floodplain dynamics, and flow routing around infrastructure. The system is cloud-native and capable of running thousands of parallel simulations, providing a scientifically rigorous baseline that can be augmented by AI and machine learning without sacrificing physical integrity.

Flood exposure analysis

Exposure is assessed using population and economic output as proxies for meaningful consequences. The analysis focuses on three return periods: 5-year floods (almost certain), 100-year floods (substantial), and 500-year floods (rare/severe). As of 2025, approximately $18.8 trillion in global GDP is located in areas facing substantial flood risk. Strikingly, nearly $11.7 trillion in GDP is exposed to almost certain flood disruption, with a close to guaranteed chance of flooding occurring at least once over a 10-year period. The 1% annual probability event is a globally recognised indicator used to form a common foundation for risk communication.

Administrative hotspots

At the global scale, flood exposure is concentrated in South and East Asia, where large populations live across expansive river floodplains. In countries like India and Pakistan, inundation can affect tens of millions of people at once. The highest exposure shares occur in deltaic environments, particularly in parts of Egypt and Thailand, where flat terrain and rising sea levels leave little population outside flood-prone areas. Looking ahead, the fastest growth in exposure is concentrated in large riverine cities and rapidly urbanising lowland metros across Asia and Africa.

Asia-Pacific

Flood risk is already immense in the Asia-Pacific region, with roughly 1.44 billion people exposed in 2025, rising to 1.49 billion by 2100. Approximately $11.9 trillion in GDP is currently exposed. Absolute exposure is dominated by China’s large municipalities, such as Tianjin and Shanghai, where dense development amplifies impacts. Hotspots for population exposure include the provinces of Uttar Pradesh and Bihar in India, and Punjab in Pakistan.

Europe

Europe’s exposure remains comparatively stable but high, with 78.3 million people and $3.2 trillion in GDP at risk in 2025. Absolute exposure is concentrated in metropolitan regions like Lombardy (Milan), North Rhine-Westphalia (Cologne), and Tuscany (Florence). Future growth is led by coastal and tidally influenced regions in Great Britain, such as Lancashire and Hampshire, where sea-level rise expands flood influence inland.

Latin America

Across Latin America, 52.7 million people and $576.3 billion in GDP are exposed in 2025. Exposure is concentrated in the region’s largest metropolitan areas, including Lima, São Paulo, and Rio de Janeiro. The highest exposure shares occur on lowland plains and basin floors, with hotspots such as the Andrés Ibáñez Department in Bolivia and the Recife Metropolitan Region in Brazil.

Middle East and North Africa

MENA has 128.4 million people exposed in 2025, a figure expected to remain stable through 2100. However, GDP exposure is projected to rise from $395 billion to $407.4 billion as risk shifts into more economically productive areas. Exposure is heavily concentrated in the Nile Delta, with governorates like Kafr El-Sheikh and Dakahlia exhibiting near-total exposure shares today.

North America

In North America, 45.8 million people and $2.2 trillion in GDP are currently exposed. Absolute exposure is concentrated in large counties like Harris County, Texas, and dense municipalities in the Mexico City basin, including Nezahualcóyotl and Gustavo A. Madero. Growth is driven by expanding hazards in areas such as Clark County, Nevada, and coastal New York.

Africa

Sub-Saharan Africa faces high and rising exposure, with 178.3 million people at risk in 2025, alongside $584.1 billion in GDP. Absolute risk is concentrated in capital regions like Analamanga (Madagascar) and Abidjan (Côte d’Ivoire). The region is projected to see the fastest growth in population exposure, driven by intensifying rainfall and urban inundation in cities like Abidjan and parts of Ethiopia.

Flood risk is already here

Substantial flood risk is already embedded in the global footprint of where people live and economies operate. With 1.92 billion people and $18.8 trillion in GDP exposed to a 1% annual chance event, the central challenge is managing existing risk that intersects with high-value activity across river basins and urban centres. The FS-GFM provides a basis for prioritising resilience investments and improving financial protection over the coming decades.