Abstract This study presents a synthesis of century-scale hydroclimate variations in North America for the Common Era (last 2000 years) using new age models of previously published multiple proxy-based paleoclimate data. This North American Hydroclimate Synthesis (NAHS) examines regional hydroclimate patterns and related environmental indicators, including vegetation, lake water elevation, stream flow and runoff, cave drip rates, biological productivity, assemblages of living organisms, and salinity. Centennial-scale hydroclimate anomalies are obtained by iteratively sampling the proxy data on each of thousands of age model realizations and determining the fractions of possible time series indicating that the century-smoothed data was anomalously wet or dry relative to the 100 BCE to 1900 CE mean. Results suggest regionally asynchronous wet and dry periods over multidecadal to centennial timescales and frequent periods of extended regional drought. Most sites indicate drying during previously documented multicentennial periods of warmer Northern Hemisphere temperatures, particularly in the western U.S., central U.S., and Canada. Two widespread droughts were documented by the NAHS: from 50 BCE to 450 CE and from 800 to 1100 CE. Major hydroclimate reorganizations occurred out of sync with Northern Hemisphere temperature variations and widespread wet and dry anomalies occurred during both warm and cool periods. We present a broad assessment of paleoclimate relationships that highlights the potential influences of internal variability and external forcing and supports a prominent role for Pacific and Atlantic Ocean dynamics on century-scale continental hydroclimate.

中文翻译：

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共同时代的北美水文气候合成 (NAHS)

摘要 本研究使用先前发布的多个基于代理的古气候数据的新时代模型，对共同时代（过去 2000 年）北美百年尺度的水文气候变化进行了综合。这份北美水文气候综合 (NAHS) 研究了区域水文气候模式和相关的环境指标，包括植被、湖水海拔、溪流和径流、洞穴滴水率、生物生产力、生物体的组合和盐度。百年尺度的水文气候异常是通过对数千个年龄模型实现中的每一个的代理数据进行迭代采样并确定可能的时间序列的分数来获得的，这些部分表明世纪平滑数据相对于公元前 100 年至公元 1900 年的平均值异常潮湿或干燥. 结果表明，在几十年到百年的时间尺度上，区域性干湿期不同步，并且区域性干旱频繁发生。大多数地点都表明在先前记录的北半球温度升高的数百年期间发生干燥，特别是在美国西部、美国中部和加拿大。NAHS 记录了两次大面积干旱：公元前 50 年至公元 450 年和公元 800 年至公元 1100 年。主要的水文气候重组与北半球温度变化不同步，温暖和凉爽时期都发生了广泛的干湿异常。