Steiger Nathan J, Smerdon Jason E, Cook Benjamin I, Seager Richard, Williams A Park, Cook Edward R
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA.
NASA Goddard Institute for Space Studies, New York, NY, USA.
Sci Adv. 2019 Jul 24;5(7):eaax0087. doi: 10.1126/sciadv.aax0087. eCollection 2019 Jul.
Multidecadal "megadroughts" were a notable feature of the climate of the American Southwest over the Common era, yet we still lack a comprehensive theory for what caused these megadroughts and why they curiously only occurred before about 1600 CE. Here, we use the Paleo Hydrodynamics Data Assimilation product, in conjunction with radiative forcing estimates, to demonstrate that megadroughts in the American Southwest were driven by unusually frequent and cold central tropical Pacific sea surface temperature (SST) excursions in conjunction with anomalously warm Atlantic SSTs and a locally positive radiative forcing. This assessment of past megadroughts provides the first comprehensive theory for the causes of megadroughts and their clustering particularly during the Medieval era. This work also provides the first paleoclimatic support for the prediction that the risk of American Southwest megadroughts will markedly increase with global warming.
在公元纪年期间，持续数十年的“大干旱”是美国西南部气候的一个显著特征，但我们仍然缺乏一个全面的理论来解释这些大干旱的成因，以及为何它们奇怪地只发生在公元1600年左右之前。在此，我们结合辐射强迫估计值，使用古水动力数据同化产品，以证明美国西南部的大干旱是由异常频繁且寒冷的热带太平洋中部海表温度（SST）波动，以及异常温暖的大西洋海表温度和局部正辐射强迫共同驱动的。对过去大干旱的这一评估为大干旱的成因及其聚集现象，尤其是中世纪时期的聚集现象，提供了首个全面的理论。这项工作还首次为美国西南部大干旱风险将随着全球变暖而显著增加这一预测提供了古气候学支持。
