Did the TBJ Ilopango eruption cause the AD 536 event?

The greatest atmospheric aerosol loading event of the past two millennia occurred in the year ca. AD 536. A ‘dry fog’ (dense stratospheric aerosol cloud) enveloped the earth and was followed by protracted cooling lasting more than a decade from ca. A.D 536-550. Tree ring records, historical accounts, and archaeological evidence suggest that effects were especially pronounced in the northern hemisphere where unseasonably cold summer temperatures led to crop failures and widespread famine from China to the Mediterranean to Mesoamerica. Previous studies have invoked either a comet impact or a volcanic eruption as the likely source of the AD 536 global dust veil event, but virtually no physical evidence has been produced to convincingly tie the climatic event to a specific geophysical source. A recent revision of ice core chronologies and volcanic sulfate (SO4) deposition records from Antarctica (DML) and Greenland (Dye-3, GRIP, and NGRIP) now points to a large tropical volcanic eruption as the probable source of the AD 536 event. Here we report data on the Tierra Blanca Joven (TBJ) eruption of the Ilopango caldera in El Salvador that are consistent with the AD 536 event in terms of chronology, magnitude, and geographic location. Current tephra isopach maps including fall and flow deposits give a conservative bulk tephra volume for the TBJ event of ~84 km3, indicating a large VEI 6+ event and a magnitude of 7.0.