The Fimbulwinter Hypothesis: Volcanic Sulfate Clustering and the Climatic Forcing of Late Antique Social Collapse

The Norse myth of Fimbulwinter describes three consecutive severe winters with no summer between them. This paper proposed that the myth encoded a recurrent geophysical pattern — volcanic eruptions arriving in clusters that cool more deeply than single events. That clustering claim has since been refuted: re-run on the eVolv2k sulfate record, large eruptions are approximately Poisson-distributed, not clustered. Retained as a record of the hypothesis. What survives is the severe multi-year cooling caused by individual large eruptions, and the 536/540 CE double-event itself.