School of Geography - Research Publications

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Start date: 2020 × End date: 2021 × Author: Drysdale, Russell × Author: Bajo, Petra ×

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    Beyond one-way determinism: San Frediano’s miracle and climate change in Central and Northern Italy in late antiquity
    Zanchetta, G ; Bini, M ; Bloomfield, K ; Izdebski, A ; Vivoli, N ; Regattieri, E ; Isola, I ; Drysdale, RN ; Bajo, P ; Hellstrom, JC ; Wiśniewski, R ; Fallick, AE ; Natali, S ; Luppichini, M (Springer (part of Springer Nature), 2021-03-20)
    Integrating palaeoclimatological proxies and historical records, which is necessary to achieve a more complete understanding of climate impacts on past societies, is a challenging task, often leading to unsatisfactory and even contradictory conclusions. This has until recently been the case for Italy, the heart of the Roman Empire, during the transition between Antiquity and the Middle Ages. In this paper, we present new high-resolution speleothem data from the Apuan Alps (Central Italy). The data document a period of very wet conditions in the sixth c. AD, probably related to synoptic atmospheric conditions similar to a negative phase of the North Atlantic Oscillation. For this century, there also exist a significant number of historical records of extreme hydroclimatic events, previously discarded as anecdotal. We show that this varied evidence reflects the increased frequency of floods and extreme rainfall events in Central and Northern Italy at the time. Moreover, we also show that these unusual hydroclimatic conditions overlapped with the increased presence of “water miracles” in Italian hagiographical accounts and social imagination. The miracles, performed by local Church leaders, strengthened the already growing authority of holy bishops and monks in Italian society during the crucial centuries that followed the “Fall of the Roman Empire”. Thus, the combination of natural and historical data allows us to show the degree to which the impact of climate variability on historical societies is determined not by the nature of the climatic phenomena per se, but by the culture and the structure of the society that experienced it.
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    Persistent influence of obliquity on ice age terminations since the Middle Pleistocene transition
    Bajo, P ; Drysdale, RN ; Woodhead, JD ; Hellstrom, JC ; Hodell, D ; Ferretti, P ; Voelker, AHL ; Zanchetta, G ; Rodrigues, T ; Wolff, E ; Tyler, J ; Frisia, S ; Spotl, C ; Fallick, AE (AMER ASSOC ADVANCEMENT SCIENCE, 2020-03-13)
    Radiometric dating of glacial terminations over the past 640,000 years suggests pacing by Earth's climatic precession, with each glacial-interglacial period spanning four or five cycles of ~20,000 years. However, the lack of firm age estimates for older Pleistocene terminations confounds attempts to test the persistence of precession forcing. We combine an Italian speleothem record anchored by a uranium-lead chronology with North Atlantic ocean data to show that the first two deglaciations of the so-called 100,000-year world are separated by two obliquity cycles, with each termination starting at the same high phase of obliquity, but at opposing phases of precession. An assessment of 11 radiometrically dated terminations spanning the past million years suggests that obliquity exerted a persistent influence on not only their initiation but also their duration.