Floods and droughts in the Mississippi River basin are perennial hazards that cause severe economic disruption. Here we develop and analyze a new lipid biomarker record from Horseshoe Lake (Illinois, USA) to evaluate the climatic conditions associated with hydroclimatic extremes that occurred in this region over the last 1,800 years. We present geochemical proxy evidence of temperature and moisture variability using branched glycerol dialkyl glycerol tetraethers (brGDGTs) and plant leaf wax hydrogen isotopic composition (δ²H_wax) and use isotope‐enabled coupled model simulations to diagnose the controls on these proxies. Our data show pronounced warming during the Medieval era (CE 1000–1,600) that corresponds to midcontinental megadroughts. Severe floods on the upper Mississippi River basin also occurred during the Medieval era and correspond to periods of enhanced warm‐season moisture. Our findings imply that projected increases in temperature and warm‐season precipitation could enhance both drought and flood hazards in this economically vital region.

中文翻译：

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脂质生物标志物记录文件记录了共同时期密西西比河流域的水文气候变化

密西西比河流域的洪水和干旱是常年发生的灾害，会造成严重的经济中断。在这里，我们开发并分析了来自马蹄湖（美国伊利诺伊州）的新脂质生物标志物记录，以评估与该地区在过去1800年中发生的极端极端气候有关的气候条件。温度和湿度变化的使用支化甘油二烷基甘油四醚（brGDGTs）和植物叶蜡氢同位素组成，我们本地球化学代理证据（δ ² ħ_蜡），并使用支持同位素的耦合模型仿真来诊断这些代理的控件。我们的数据显示，中世纪时期（公元1000-1,600年）出现了明显的变暖，这与大陆中部大干旱相对应。在中世纪时期，密西西比河上游流域也发生了严重洪灾，这对应于暖季水分增加的时期。我们的发现表明，在这个经济至关重要的地区，预计温度升高和暖季降水会增加干旱和洪水的危害。