Most flood maps show rivers bursting their banks. But in cities, much of the damage now comes from sudden cloudbursts that overwhelm drains and send water down streets and into basements, often far from any river.
Every monsoon, roads in Indian cities vanish under water, trains stall and commutes stretch into hours. Usually the response starts only after the rain: pumping, rerouting and cleaning up.
Floods cause more damage than almost any other natural hazard, yet for much of the world nobody can say which streets, farms or factories will go under in a 1 in 100 year storm, let alone in a warmer climate.
When a bank lends against a warehouse in Houston or a hotel on the Spanish coast, it prices credit risk and market risk in great detail, but until recently it had little hard data on how floods, heat or wildfire might wipe out the value of the collateral.
A solar farm in Andalusia, a warehouse near Valencia and a hotel on a Greek island face very different futures as the climate warms, but most companies still judge their sites with weather records from the past.
