Northern Rocky Mountain Science Center, US Geological Survey, Bozeman, MT 59717;
Northern Rocky Mountain Science Center, US Geological Survey, Bozeman, MT 59717.
Proc Natl Acad Sci U S A. 2020 May 26;117(21):11328-11336. doi: 10.1073/pnas.1916208117. Epub 2020 May 11.
Across the Upper Missouri River Basin, the recent drought of 2000 to 2010, known as the "turn-of-the-century drought," was likely more severe than any in the instrumental record including the Dust Bowl drought. However, until now, adequate proxy records needed to better understand this event with regard to long-term variability have been lacking. Here we examine 1,200 y of streamflow from a network of 17 new tree-ring-based reconstructions for gages across the upper Missouri basin and an independent reconstruction of warm-season regional temperature in order to place the recent drought in a long-term climate context. We find that temperature has increasingly influenced the severity of drought events by decreasing runoff efficiency in the basin since the late 20th century (1980s) onward. The occurrence of extreme heat, higher evapotranspiration, and associated low-flow conditions across the basin has increased substantially over the 20th and 21st centuries, and recent warming aligns with increasing drought severities that rival or exceed any estimated over the last 12 centuries. Future warming is anticipated to cause increasingly severe droughts by enhancing water deficits that could prove challenging for water management.
在整个密苏里河流域上游，2000 年至 2010 年的近期干旱被称为“世纪之交干旱”，其严重程度可能超过包括尘暴干旱在内的所有仪器记录中的干旱。然而，直到现在，还缺乏足够的代理记录来更好地了解这一事件的长期变化。在这里，我们研究了来自密苏里河流域上游 17 个新的基于树木年轮的流量记录和一个独立的温暖季节区域温度重建的网络，以将近期干旱置于长期气候背景下。我们发现，自 20 世纪后期（1980 年代）以来，温度通过降低流域的径流效率，越来越多地影响干旱事件的严重程度。极端高温、更高的蒸散量以及流域内相关的低流量条件的发生，在 20 世纪和 21 世纪大幅增加，最近的变暖与不断增加的干旱严重程度相吻合，这些严重程度可与过去 12 个世纪中的任何一次相媲美，甚至超过。预计未来的变暖将通过加剧水资源短缺而导致越来越严重的干旱，这可能对水资源管理构成挑战。
