Overview
- The Cambridge–Leibniz team synthesizes ice-core, tree-ring and documentary records to argue a climate shock set conditions for the pandemic’s arrival.
- Ice cores from Greenland and Antarctica show a major sulfur spike in 1345, ranked 18th in 2,000 years and consistent with a stratospheric tropical eruption.
- Tree rings across eight European regions register consecutive cold, wet summers in 1345–1347, matching reports of hazy skies and dark lunar eclipses.
- Famine pressures led Venice, Genoa and Pisa to import grain from the Golden Horde’s Black Sea ports in 1347, a route the authors say likely carried plague-infected fleas.
- The pathway dovetails with 2022 evidence for a Central Asian source of Yersinia pestis, though the volcano’s identity is unknown and causation remains unproven.