Atmospheric rivers (ARs) are narrow corridors of concentrated moisture known to distribute moisture globally and influence extreme precipitation events. However, the contribution of ARs to rare flood risk, the resultant hazard from extreme precipitation events, remains unquantified. Here, using 2686 largely regulation-free catchments across the world, we find that in some regions ARs are linked to over 70% of the largest precipitation and streamflow events. AR related precipitation significantly shortens the recurrence intervals of large flood events, making them 2–8 times more likely. In parts of Northern America, Europe and Australia, rare flood events are up to 12 times more likely when an AR is present. We conclude that ARs play a crucial role in increasing the frequency of extreme hydrological events on a global scale.

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