Climate change is expected to have a significant impact on water security, with higher temperatures causing both enhanced droughts and flood extremes. Here, using global flow data from non-urban catchments, we investigate the sensitivity of flood volume to changes in concurrent surface air temperature. We find most of the world shows decreases in flood volumes with increasing temperature. To understand why this correlation exists, we assess the sensitivity of the above result to mean daily temperatures (climate region), catchment size, and severity of the flood event. Our results indicate that most of the world shows decreases in flood volume with rising temperature for frequent events (50th percentile in this study) and a lesser decrease for rarer events. Changes in the flood volume in tropical regions show the greatest sensitivity to flood percentiles and catchment size. Large catchments in the tropics (≥ 1000 km²) have considerable sensitivities of flood volume with temperature at rates of -10 to -5%/ °C for frequent events (< 90th percentile) whereas small catchments (1000 km²) have sensitivities that only -5%/ °C or greater (i.e., less magnitude). On the other hand, when temperature increases, smaller catchments in the regions are likely to be exposed to more severe flooding at rates up to 15%/ °C for the most severe floods (99.99 percentile in this study) while the rate for large catchments approach zero. Although this study does not seek to find a causality between air temperature and flood runoff, the results suggest a possible decrease in water security with climate change, particularly in large tropical catchments.

气候变化预计将对水安全产生重大影响，气温升高会导致干旱和洪水极端事件加剧。在这里，我们使用来自非城市集水区的全球流量数据，研究洪水量对同时地表气温变化的敏感性。我们发现世界上大部分地区的洪水量都随着温度的升高而减少。为了理解为什么存在这种相关性，我们评估了上述结果对平均每日温度（气候区域）、流域面积和洪水事件严重程度的敏感性。我们的研究结果表明，世界大部分地区的洪水量随着温度升高而减少，频繁事件（本研究中的第 50 个百分位）和罕见事件的减少幅度较小。热带地区洪水量的变化对洪水百分位数和集水面积的敏感性最大。热带地区的大型集水区（≥ 1000 km² ) 对于频繁事件（< 90th 百分位），洪水量对温度的敏感度为 -10 至 -5%/°C，而小流域（1000 km ²）的敏感度仅为 -5%/°C 或更高（即，幅度较小）。另一方面，当温度升高时，该地区较小的集水区可能会遭受更严重的洪水，最严重的洪水（本研究中为 99.99 个百分点）的速率高达 15%/°C，而大型集水区的速率可能会更高。接近零。尽管这项研究并未试图找到气温和洪水径流之间的因果关系，但结果表明气候变化可能会降低水安全，特别是在大型热带集水区。