Human-driven climate change and land management are making dangerous floods more likely and more intense across much of the planet, a new modeling study has found.
Researchers examined how river floods respond to different levels of warming between 1.5 and 3 degrees Celsius above preindustrial temperatures. They used simulations of river discharge that explicitly include human land and water management, which standard climate models often simplify or neglect.
Scale of projected flood risk
Under 1.5 to 3 degrees of human-induced warming, 60% to 70% of Earth’s land surface is projected to see rising flood risk, with the largest increases in tropical regions. The study finds that the change is driven mainly by larger flood magnitudes, rather than only by more frequent events.
On a global average, floods become about 10% more probable at 2 degrees of warming compared with 1.5 degrees. The authors note that this shift in probability, combined with higher peak flows, translates into a substantial increase in potential damage to communities, infrastructure, and agriculture.
Human fingerprint on floods
The study separates the influence of natural variability from that of human activities, including greenhouse gas emissions and past land and water management. Near major hydrological basins, up to 88% of the increase in flood risk would not occur without human-driven climate change and those management choices, according to the analysis.
By 2065, the imprint of human actions on flood behavior is projected to be clearly detectable across nearly 40% of global land area. This means that in many regions, observed changes in flood patterns over the coming decades will be statistically attributable to human influence rather than natural swings in climate alone.
Why management choices matter
The modeling framework incorporates dams, reservoirs, irrigation, and other interventions that alter how water moves through landscapes. By explicitly representing these factors, the researchers show that human decisions about where and how to store, divert, or drain water can amplify or modulate the flood impacts of a warming climate.
The results suggest that, without changes in current practices, many river basins will face compound risks from both stronger climate-driven extremes and legacy land and water management. In tropical regions in particular, rapidly growing populations and expanding infrastructure are likely to intersect with these heightened physical hazards.
Implications for policy and planning
The authors argue that accounting for human management is essential for realistic flood risk projections and for designing effective adaptation strategies. Their findings indicate that decisions taken now about emissions, land use, and river regulation will strongly shape how much additional flood danger materializes by mid-century.
Because a large share of the projected risk increase is directly linked to human activity, the study suggests that both mitigation of greenhouse gas emissions and targeted changes in water and land management could substantially limit future flood losses.
Reference
- Chen, Y., Gu, X., Wang, L., Lai, Y., Li, J., Marengo Orsini, J. A., et al. (2026). Enhancement of global flood risk due to greater flood magnitude and variability under anthropogenic activities. Journal of Geophysical Research: Atmospheres, 131, e2025JD044105. https://doi.org/10.1029/2025JD044105
- AGU News
