A 1600-year record of extreme rainfall in northern Arabia.

Intense rain can trigger flashfloods in Arabia. Torrential rains in 2024 sowed widespread chaos in the region. Sediment-loaded plumes discharged by flashfloods deposit onto the seabed. Burrowing animals disrupt these flood layers, erasing the paleorainfall record. Fortuitously, we discovered an anoxic deep-sea brine pool sited close enough to shore to chronicle floods, yet be otherwise undisturbed by animals. Cores retrieved from the pool delivered a 1600-year rainfall record. We merge these core-layer histories with modern rainfall statistics, satellite observations, and simulations to deliver a high-resolution quantitative Late Holocene hydroclimate record for Arabia. We find that the modern era is 2.5 times drier than the last 1.6 thousand years. The Little Ice Age stands out as particularly wet. That period experienced a fivefold increase in rainfall intensity compared to today. Though hyperarid now, the flood layers demonstrate that climate shifts can generate weather conditions unwitnessed in the modern era. Such long-range insight is crucial for framing uncertainties surrounding future hydroclimate forecasts.