A new study examines the risk of flooding during climate change

Fathom, a global expert in water risk intelligence, has produced what are said to be the most accurate forecasts to date of flood risks under climate change.

Published in Water Resources Research, the study compared current inland and coastal flood risks with projections for the years 2050 and 2100, examining both the optimistic low emissions scenario (SSP1-2.6) and the high emissions scenario (SSP5-8.5). An optimistic scenario can only be realized if all global carbon reduction targets are fully met.

The findings show that under the low emissions scenario, flood risks are expected to increase by an average of 9% in 2100 compared to 2020, with potential effects ranging from a 6% to 29% decrease. In contrast, the state of the air pollutants predict a significant increase in flood risks, with an expected increase of 49% by the end of the century, and a potential range from 7% to 109%.

Near-term projections up to 2050 show a slight increase in flood risks, with a 7% increase under the low emissions scenario and 15% under the no air pollution scenario. These scenarios show significant overlap in their potential impacts by 2050, with low scenarios ranging between a 7% decrease and 26% increase, and high scenarios ranging between a 5% decrease and a 43% increase. After 2050, the differences between the scenarios become more pronounced.

Coastal flooding is expected to continue to increase in both scenarios due to the delayed response of the ocean to the prevailing warming. Even under a promising scenario of low emissions, coastal flooding risks could increase by 99% by 2100.

Significant increases in flooding are expected along coastlines around the world, in tropical Africa and Asia, and in the arid regions of North Africa, although these projections carry a high degree of uncertainty. The greatest certainty of increased flood risk exists along the coasts of the North Atlantic and Indian Ocean, as well as Southeast Asia and the Pacific islands.

The study also emphasized the great uncertainty that remains in climate forecasting, mainly due to the lack of measurement data, insufficient information on flood protection, and the inevitable errors caused by missing data.

It represents a major advance in global flood simulation, research that builds on nearly a decade of flood model development. These models have greatly improved the resolution, physical accuracy, and integration of climate change data, allowing for more accurate estimates of population exposure, property risk, flood protection cost analysis, and future loss projections.

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