GAR 2025 Hazards: Floods
Recent data suggests that floods account for up to 35–40% of weather-related disaster occurrences.
Between 1970 and 2019, water-related hazards accounted for 50% of all disasters and 45% of all reported deaths. Since 2000, the number of recorded flood-related disasters has risen by 134% compared with the two previous decades.
Probabilistic approaches can also help understanding flood risk over time, beyond the specific fluctuations that may occur from year to year. By providing a consistent metric to measure and compare potential damages annually, it can help guide decisions about flood protection and land use, particularly in the content of climate change and rapid urbanization. This is crucial, given that riverine and overflow floods are the costliest of the three hazard types covered here, with average annual losses of USD 388.4 billion, including USD 74.1 billion. Meanwhile, the Annual Average Losses (AAL) from tropical cyclones is estimated at USD 119.5 billion, including USD 95.5 billion in infrastructure.
Floods and storms are responsible for a range of often unaccounted indirect impacts to people and planet, destroying ecosystems and driving disaster-related displacement. The number of people exposed to floods globally has also steadily risen from 28.1 million in 1970 to 35.1 million in 2020—an increase of 24.9%. Most flood-related deaths and economic losses are recorded in Asia.
Annual Average Economic Losses in USD by Floods and Cyclones for the Critical Infrastructure
As outlined in GAR 2025 - Chapter 3, floods and storms also have a wide range of indirect impacts that can hold back development. For example, recently modelling of the effects of climate-related disasters in Bangladesh explored how these affected access to infrastructure and slowed progress on the SDGs. The study found the poor were disproportionately at risk in coastal districts and estimated that targeting climate adaptation towards these at-risk communities could help safeguard 50–85% of achieved progress across a range of key SDG indicators. This highlights the broader development impacts of climate-related disasters in a range of developmental sectors.
Floods and cyclones pose a major hazard for the education sector across all regions, representing the large majority of disaster-related AAL in the sector.
Future Flood risk
Currently, the annual average losses associated with flooding totals USD 388 billion globally. This is projected to rise considerably soon as a result of climate change. By 2050, models suggest that the average annual losses to infrastructure from riverine flooding will increase between 5% (under the low-emission RCP 2.6 climate scenario) and 13% (under the high-emission RCP8.5 scenario), reaching USD 407–439 billion in annual losses.
Not all regions will see the same flood hazard trends under these projections. While some regions may get dryer and be more affected by drought rather than flooding (such as Southern Europe, Australia and New Zealand, Central America or Southern Africa). Other regions may experience higher average annual losses as a result of more frequent and intense flooding: for example, Western Asia (+60%), Melanesia (+44%), Eastern Africa (+42%), Middle Africa (+31%), Eastern Europe (+28%), Southern Asia (+23%), Northern Africa (+19%) or Central Asia (+17%).
GAR 2025 Hazard explorations
For the big five major hazard groups (earthquakes, floods, storms, drought and heat) the recorded direct economic costs came to over USD 195.7 billion in 2023, constituting 0.015% of global GDP that year.
Earthquakes account for over a quarter (25.6%) of global economic disaster losses.
Recent data suggests that floods account for up to 35–40% of weather-related disaster occurrences.
In some regions, storms account for up to 35% of total recorded disaster costs, driven by high winds, storm surges, and heavy rainfall.
Droughts often unfold slowly, but with far-reaching impacts on agriculture, water supplies, and economic stability.
In recent years, extreme heat has become the leading cause of reported weather-related deaths
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