Anthropogenic climate change accelerates the onset of global flood timing.

Floods are among Earth's most devastating natural disasters, with cascading societal and ecological impacts. Flood timing shifts amplify risks by disrupting preparedness, yet their global patterns remain largely unquantified. Using multi-model ensembles, we provide a global-scale assessment of flood timing changes under incremental warming (1.5 °C-4.0 °C). Here we show that anthropogenic forcing advances global flood timing by 0.43 ± 0.25 days per 0.5 °C of warming, with regional divergence: early-flood regions shift even earlier, while late-flood regions experience further delay. At 1.5 °C, 50.73 ± 4.23% of global land area faces flood timing shifts greater than 7 days, escalating to 52.85 ± 3.20% at 2.0 °C. Countries including China, India, and the United States are projected to experience greater population exposure. These findings highlight the need to change how flood risk is conceptualized and managed. The traditional focus on flood magnitude and frequency must expand to incorporate timing as a fundamental variable in climate adaptation planning.