More than Laki. Compound Climate Shocks and Icelandic Volcanism in the Nordic World of the 1780s

Abstract. The article investigates the 1783–1784 Laki flood lava eruption as a case of regionally differentiated volcanic climate impacts and compound climate–society shocks in the Nordic countries. Drawing on recent advances in paleoclimate reanalysis (ModE-RA), early instrumental weather observations, dendroclimatology, and local environmental histories, it reconstructs seasonal and spatial patterns of climate anomalies and their societal repercussions from Iceland to Finland. A model–data comparison reveals marked regionality: while ModE-RA indicates pronounced post-eruption cooling from 1784 to 1786, instrumental and proxy evidence show strong sub-regional contrasts, including a preceding unrelated severe spring–summer drought in southern Scandinavia and notable discrepancies between ensemble simulations and observed autumn 1783 and winter 1783/84 temperature patterns. The study conceptualizes the Laki crisis as a compound event in the Nordic countries, in which volcanic cooling interacted with antecedent warmth and drought, atmospheric pollution, societal tensions, and institutional vulnerabilities. Pre-eruption drought and grain harvest failures in Denmark and southern and central Sweden, eruption-related toxic haze and vegetation damage in Iceland, and subsequent cold seasons combined to produce cascading impacts on harvests, food prices, mortality, and social protest, with peak demographic and political effects lagging 2–3 years after the eruption and food crises. By systematically integrating “archives of nature” and “archives of society” across multiple Nordic polities, this study illustrates how an interdisciplinary climate history framework can capture the regional complexity of volcanic forcing and climatic anomalies, clarify tensions between models and observations, and explain divergent societal trajectories under compound climatic stress.