Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.
NASA Goddard Institute of Space Studies, New York, NY 10025, USA.
Science. 2020 Apr 17;368(6488):314-318. doi: 10.1126/science.aaz9600.
Severe and persistent 21st-century drought in southwestern North America (SWNA) motivates comparisons to medieval megadroughts and questions about the role of anthropogenic climate change. We use hydrological modeling and new 1200-year tree-ring reconstructions of summer soil moisture to demonstrate that the 2000-2018 SWNA drought was the second driest 19-year period since 800 CE, exceeded only by a late-1500s megadrought. The megadrought-like trajectory of 2000-2018 soil moisture was driven by natural variability superimposed on drying due to anthropogenic warming. Anthropogenic trends in temperature, relative humidity, and precipitation estimated from 31 climate models account for 47% (model interquartiles of 35 to 105%) of the 2000-2018 drought severity, pushing an otherwise moderate drought onto a trajectory comparable to the worst SWNA megadroughts since 800 CE.
西南北美地区（SWNA）21 世纪严重且持续的干旱促使人们将其与中世纪大干旱进行比较，并对人为气候变化的作用提出了质疑。我们使用水文模型和新的 1200 年夏季土壤湿度树木年轮重建，证明了 2000-2018 年 SWNA 干旱是自公元 800 年以来第二干旱的 19 年周期，仅次于 16 世纪后期的大干旱。2000-2018 年土壤湿度的类似大干旱轨迹是由人为变暖导致的干燥之上叠加的自然变异性驱动的。31 个气候模型估计的温度、相对湿度和降水的人为趋势占 2000-2018 年干旱严重程度的 47%（模型四分位距为 35%至 105%），将本来中等程度的干旱推向了与自公元 800 年以来 SWNA 最严重的大干旱相当的轨迹。
