In the middle of the sixth century, witnesses across the Mediterranean and Near East described a strange year when daylight felt like twilight and the sun “gave forth its light without brightness.” Geology supports this claim. Ice cores show huge injections of volcanic sulfate into the stratosphere beginning in 536 and again around 540, while tree rings from Eurasia and beyond record summers that turned sharply colder. Historians often call the resulting chill the Late Antique Little Ice Age, a multi-decade cool spell that began with this dust veil.

What happened appears to be a sequence of powerful eruptions that lofted sulfur aerosols high into the sky, where they reflected sunlight and dimmed the world below. The leading reconstruction points to one high-latitude Northern Hemisphere eruption in 536 followed by a large tropical eruption in 540, with a third pulse later in the decade. These events rivaled or exceeded the cooling punch of far more famous blasts. The climate signal arrives fast in the records and lingers, which matches how volcanic forcing drives short, severe downturns.

Human history felt the shock. Colder, darker summers meant poor harvests, famine pressure, and migrations. The Justinianic plague that began in the early 540s spread across a stressed landscape. Archaeology in Scandinavia and the North shows settlement abandonment, ritual hoards, and social reorganization during and after the first hit, suggesting a regional crisis that echoes the written accounts from the south. The pattern points to climate as one strand among many in a web of causes that redirected economies and states in late antiquity.

Geology helps resolve a long-standing debate about which volcanoes were responsible. For years Ilopango in El Salvador was a prime suspect. High-precision tephra and ice-core work now dates its great Tierra Blanca Joven eruption to 431 CE, which removes it from the 536 event and clarifies that the mid-sixth-century cooling began with other sources. In other words, the sky dimmed because of multiple eruptions rather than one single culprit, with the first likely in the far north and the second in the tropics.

Myth and memory keep a parallel record. Norse tradition tells of Fimbulwinter, a terrible run of winters without a summer in between. Scholars now read that story in light of the sixth-century downturn and the archaeological signals it left across Sweden and Norway. Medieval chroniclers from the Mediterranean and the Levant also mark an uncanny dimming and failed harvests. Poetry, saga, and annals move in step with ice and oak, and together they trace how climate can reach into ritual, law, and legend.

What can we do with this information?
We can understand our vulnerability. This doesn’t mean we become doomsday preppers, but perhaps we buy a few extra cans of food when we go to the grocery store and learn how to seal rice for long-term keeping.
Do you think humanity is prepared if another event were to occur? How can we protect not only ourselves, but communities as well?

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