ABSTRACT

Heavy precipitation events increased over the last century in response to higher atmospheric temperature and associated increases in water vapor content, but little evidence shows that increased heavy precipitation changed flood trends. Short records, containing few extreme flood observations, limit statistical examination of relationships between global temperature, heavy precipitation, and extreme floods. We synthesized European and North American sediment-based paleoflood records extending through at least 900 CE. These records captured flood variability during the warmer Medieval Climate Anomaly (MCA) and cooler Little Ice Age (LIA). Twelve paleoflood chronologies chosen for the analysis suggest an increase in flood frequency since 1000 CE. The largest magnitude floods mostly occurred between 1000 and 1300 CE after peak MCA temperature during a relatively drier overall climate regime. The association found between large magnitude floods during a drier climate may be explained by increased atmospheric water vapor capacity from warmer temperatures that intensified precipitation events. Despite limitations in the number of studies available, extreme flood observations reveal a pattern of large magnitude floods in the late MCA and frequent floods in the LIA. Therefore, temperature–precipitation relationships may influence flood variability, and flood magnitude will likely become more extreme as global temperatures rise.

摘要

上个世纪强降水事件因大气温度升高和相关的水汽含量增加而增加，但几乎没有证据表明强降水增加改变了洪水趋势。包含极少极端洪水观测的简短记录限制了对全球温度、强降水和极端洪水之间关系的统计检查。我们综合了至少延续至公元 900 年的欧洲和北美基于沉积物的古洪水记录。这些记录记录了温暖的中世纪气候异常 (MCA) 和凉爽的小冰河时代 (LIA) 期间的洪水变化。为分析选择的十二个古洪水年表表明自公元 1000 年以来洪水频率增加。最大规模的洪水大多发生在公元 1000 年至 1300 年之间，在相对干燥的整体气候条件下，MCA 温度达到峰值之后。在较干燥的气候期间发现的大规模洪水之间的关联可能是由于气温升高导致降水事件加剧，大气水蒸气容量增加。尽管可用研究的数量有限，但极端洪水观测揭示了 MCA 晚期发生大规模洪水和 LIA 频繁发生洪水的模式。因此，温度-降水关系可能会影响洪水变率，随着全球气温上升，洪水强度可能会变得更加极端。在较干燥的气候期间发现的大规模洪水之间的关联可能是由于气温升高导致降水事件加剧，大气水蒸气容量增加。尽管可用研究的数量有限，但极端洪水观测揭示了 MCA 晚期发生大规模洪水和 LIA 频繁发生洪水的模式。因此，温度-降水关系可能会影响洪水变率，随着全球气温上升，洪水强度可能会变得更加极端。在较干燥的气候期间发现的大规模洪水之间的关联可能是由于气温升高导致降水事件加剧，大气水蒸气容量增加。尽管可用研究的数量有限，但极端洪水观测揭示了 MCA 晚期发生大规模洪水和 LIA 频繁发生洪水的模式。因此，温度-降水关系可能会影响洪水变率，随着全球气温上升，洪水强度可能会变得更加极端。