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Abstract. Narrative evidence contained within historical documents and inscriptions provides an important record of climate variability for periods prior to the onset of systematic meteorological data collection. A common approach used by historical climatologists to convert such qualitative information into continuous quantitative proxy data is through the generation of ordinal-scale climate indices. There is, however, considerable variability in the types of phenomena reconstructed using an index approach and the practice of index development in different parts of the world. This review, written by members of the PAGES (Past Global Changes) CRIAS working group – a collective of climate historians and historical climatologists researching Climate Reconstructions and Impacts from the Archives of Societies – provides the first global synthesis of the use of the index approach in climate reconstruction. We begin by summarising the range of studies that have used indices for climate reconstruction across six continents (Europe, Asia, Africa, the Americas, and Australia) as well as the world's oceans. We then outline the different methods by which indices are developed in each of these regions, including a discussion of the processes adopted to verify and calibrate index series, and the measures used to express confidence and uncertainty. We conclude with a series of recommendations to guide the development of future index-based climate reconstructions to maximise their effectiveness for use by climate modellers and in multiproxy climate reconstructions.

Scholars in many disciplines have used diverse methods and sources to establish that, between the 15th and 18th centuries, a “Little Ice Age” considerably cooled Earth's climate. In four particularly chilly periods—the Spörer Minimum, Grindelwald Fluctuation, Maunder Minimum, and Dalton Minimum—falling temperatures both caused and reflected changes in atmospheric circulation that altered regional patterns of precipitation. Many scholars have argued that weather in these cold periods provoked or worsened regional food shortages, famines, rebellions, wars, and outbreaks of epidemic disease, in ways that may have contributed to mass mortality across the early modern world. More recently, some scholars have contrasted the fates of societies or communities that were “vulnerable” to climate change with those that were “resilient” or even consciously or unconsciously adaptive in the face of the Little Ice Age. Overall, research that connects climatic and social histories has suggested that human decisions, political structures, economic arrangements, institutions, and cultures either magnified or mitigated the impact of climate change on the societies of the early modern world. This article is categorized under: Climate, History, Society, Culture > Major Historical Eras

Abstract. Paleoclimate reconstructions have identified a period of exceptional summer and winter cooling in the North Atlantic region following the eruption of the tropical volcano Huaynaputina (Peru) in 1600 CE. A previous study based on numerical climate simulations has indicated a potential mechanism for the persistent cooling in a slowdown of the North Atlantic subpolar gyre (SPG) and consequent ocean–atmosphere feedbacks. To examine whether this mechanism could have been triggered by the Huaynaputina eruption, this study compares the simulations used in the previous study both with and without volcanic forcing and this SPG shift to reconstructions from annual proxies in natural archives and historical written records as well as contemporary historical observations of relevant climate and environmental conditions. These reconstructions and observations demonstrate patterns of cooling and sea-ice expansion consistent with, but not indicative of, an eruption trigger for the proposed SPG slowdown mechanism. The results point to possible improvements in future model–data comparison studies utilizing historical written records. Moreover, we consider historical societal impacts and adaptations associated with the reconstructed climatic and environmental anomalies.

In the North Sea region, the so-called Little Ice Age reached a cold, stormy nadir between 1560 and 1720, with a three-decade interruption of warmer, more tranquil weather between 1629 and 1662. Newly considered ship logbooks, diaries and other documentary evidence suggest that a rise in the frequency of easterly winds accompanied the coldest phases of the Little Ice Age, and these decadal climatic trends had consequences for regional warfare. Fought between 1652 and 1674, the Anglo-Dutch wars at sea were contested in a period of transition between decade-scale climatic regimes and consequently provide useful case studies into the relationship between meteorological trends and early modern military operations. In the first war, persistent westerly winds born of a warmer climate frequently helped crews aboard larger English warships set the terms of most naval engagements. However, during the second and third wars more frequent easterlies stimulated by a cooler climate granted critical advantages to Dutch fleets that had adopted elements of English tactics and technology. Ultimately, the changing climate of the Little Ice Age must be considered alongside human agency and the political, economic or cultural influences typically examined by military historians to explain the course of early modern warfare.