China's growing human displacement risk caused by floods under 1.5 °C and 2.0 °C global warming and beyond

Human displacement is one of the most pressing global issues, and China has the world's largest population affected by floods. Yet, the spatial and temporal variations of China's Human Displacement Risk (HDR) caused by floods remain unclear. Here, we investigated China's HDR caused by extreme floods under different global warming levels, including 1.5 degrees C, 2.0 degrees C and beyond. We developed an approach to estimate human displacement caused by floods in China. Based on this method, our findings indicate that China's HDR will increase by similar to 10.7 (similar to 11.0) times under 1.5 degrees C (2.0 degrees C) warming, and each 0.5 degrees C warming will increase HDR by 3 million on average. These great increases are mainly driven by climate change rather than population variations. Our results also reveal that the relationship between human displacement and increasing percentage of flood protection levels follows an exponential function. Additionally, we found that increasing China's current flood protection standard by similar to 46% (1.5 degrees C and 2.0 degrees C) and similar to 59% (4.5 degrees C) would reduce future HDR to the historical period level. This study provides valuable insights into China's HDR, which can aid in adaptive flood risk management amid the trend of shifting to a warmer and more extreme climate.