Abstract Climate reconstructions for the Common Era are compromised by the paucity of annually-resolved and absolutely-dated proxy records prior to medieval times. Where reconstructions are based on combinations of different climate archive types (of varying spatiotemporal resolution, dating uncertainty, record length and predictive skill), it is challenging to estimate past amplitude ranges, disentangle the relative roles of natural and anthropogenic forcing, or probe deeper interrelationships between climate variability and human history. Here, we compile and analyse updated versions of all the existing summer temperature sensitive tree-ring width chronologies from the Northern Hemisphere that span the entire Common Era. We apply a novel ensemble approach to reconstruct extra-tropical summer temperatures from 1 to 2010 CE, and calculate uncertainties at continental to hemispheric scales. Peak warming in the 280s, 990s and 1020s, when volcanic forcing was low, was comparable to modern conditions until 2010 CE. The lowest June–August temperature anomaly in 536 not only marks the beginning of the coldest decade, but also defines the onset of the Late Antique Little Ice Age (LALIA). While prolonged warmth during Roman and medieval times roughly coincides with the tendency towards societal prosperity across much of the North Atlantic/European sector and East Asia, major episodes of volcanically-forced summer cooling often presaged widespread famines, plague outbreaks and political upheavals. Our study reveals a larger amplitude of spatially synchronized summer temperature variation during the first millennium of the Common Era than previously recognised.

中文翻译：

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火山活动在共同时代气候变率和人类历史中的突出作用

摘要 中世纪之前每年解析和绝对过时的代理记录的缺乏会影响到共同时代的气候重建。在重建基于不同气候档案类型（不同时空分辨率、测年不确定性、记录长度和预测技能）的组合的情况下，估计过去的振幅范围、解开自然和人为强迫的相对作用或探索更深层次的相互关系具有挑战性气候变率与人类历史之间的关系。在这里，我们编译和分析了跨越整个共同时代的北半球所有现有夏季温度敏感树轮宽度年表的更新版本。我们应用一种新的集成方法来重建从公元 1 年到 2010 年的热带夏季气温，并计算大陆到半球尺度的不确定性。280 年代、990 年代和 1020 年代的峰值变暖，当时火山强迫较低，直到 2010 年才与现代条件相媲美。536 年 6-8 月的最低温度异常不仅标志着最冷十年的开始，也定义了晚古小冰河时代（LALIA）的开始。虽然罗马和中世纪时期的持续温暖与北大西洋/欧洲大部分地区和东亚大部分地区的社会繁荣趋势大致相符，但火山迫使夏季降温的主要事件往往预示着大范围的饥荒、瘟疫爆发和政治动荡。我们的研究表明，在共同时代的第一个千年期间，空间同步的夏季温度变化幅度比以前认识到的要大。