This research empirically analyzes the association between climate change, population size, and demographic crises as indicated by what we term “population checks,” or major wars, epidemics, and famines from AD 1000 to AD 1900 in the Northern Hemisphere based on historical records and climate reconstructions. We conducted this study at two temporal scales: (1) the entire study period of 900 years and (2) three climate phases according to temperature (cold, mild, and warm) of 300 years each. By adopting linear and nonlinear statistical methods, we found climate change and population size to have significant roles in driving the demographic crisis at the temporal scale of the entire study period. In terms of the three climate phases of 300 years each, we find that war is more closely correlated to climate change than to population size for all three phases. However, population size itself is more likely to trigger epidemics during mild and warm phases and is more important in relation to famines than climate change during all three climate phases. This study emphasizes the importance of scale in reviewing the social past in terms of climate change and population size. Empirical evidence of large-scale demographic crises within the three climate phases could also provide a timely reference for scientists or policymakers in addressing the potential effects of global warming.

中文翻译：

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前工业化北半球不同气候阶段的人口危机

这项研究根据历史记录和经验分析了气候变化、人口规模和人口危机之间的关联，正如我们所说的“人口检查”，或公元 1000 年至公元 1900 年在北半球发生的重大战争、流行病和饥荒。气候重建。我们在两个时间尺度上进行了这项研究：(1) 900 年的整个研究期和 (2) 三个气候阶段，根据温度（冷、温和和暖）分别为 300 年。通过采用线性和非线性统计方法，我们发现气候变化和人口规模在整个研究期间的时间尺度上对推动人口危机具有重要作用。就每个 300 年的三个气候阶段而言，我们发现，在所有三个阶段，战争与气候变化的关系比与人口规模的关系更密切。然而，在温和和温暖阶段，人口规模本身更有可能引发流行病，并且在所有三个气候阶段，与饥荒相关的问题比气候变化更重要。本研究强调了规模在从气候变化和人口规模方面回顾社会历史的重要性。三个气候阶段内大规模人口危机的经验证据也可以为科学家或决策者解决全球变暖的潜在影响提供及时的参考。本研究强调了规模在从气候变化和人口规模方面回顾社会历史的重要性。三个气候阶段内大规模人口危机的经验证据也可以为科学家或决策者解决全球变暖的潜在影响提供及时的参考。本研究强调了规模在从气候变化和人口规模方面回顾社会历史的重要性。三个气候阶段内大规模人口危机的经验证据也可以为科学家或决策者解决全球变暖的潜在影响提供及时的参考。