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. The Observatory found nine volcanic doublets across 2,418 years of ice core data — eruption clusters that produce 3.1 times deeper cooling than singletons. The myth encodes a recurrent geophysical pattern, not a one-time catastrophe.