Fimbulwinter: The Viking End-of-the-World Winter That May Be a Memory

In Norse mythology the end of the world begins with a winter that will not let go. Before the gods meet their enemies in their last battle, three winters arrive in a row with no summer between them, and a thick blizzard comes down from every direction, blotting out a sun that is already growing weak. The story is called Fimbulwinter, the "mighty winter", and it is the opening act of Ragnarök, the destruction of the world. Some researchers suspect it is not pure invention. It may be a memory of a real disaster.

Three winters with no summer

The tale is preserved in two old collections of Norse stories, the Prose Edda and the Poetic Edda, where it sits among a wider set of legends about the gods and the end of things. In the myth, the endless winter is the signal that the final battle is coming.

Neil Price, a leading expert on the Viking Age, thinks a story like that could have survived for centuries simply by being told out loud, passed from one generation to the next, until it was finally written down as part of the grand Norse vision of how the world ends. "We know beyond any doubt now there were a series of really drastic volcanic eruptions in the mid-500s, with enormous effects on Scandinavia, that really impacted the population," he says.

A sun that dimmed in AD 536

Those eruptions came more than two hundred years before the Viking Age is usually said to begin, in the late eighth century — a starting date that historians still argue about. In AD 536, people around the Mediterranean reported that the sun was strangely dim. The historian Procopius, writing about the wars of the eastern Roman emperor Justinian, described sunlight so weak that it looked like an eclipse. Other writers of the time noted disturbed seasons and trouble with food supplies. These witnesses were far from Scandinavia, which shows how widely the effects were felt.

More eruptions followed: one around 540 and another in 547. In a short space of time the climate was knocked about again and again. The result, Price says, was "something resembling a volcanic winter".

Ice, tree rings and a deadly harvest

Scientists can check those old reports against records kept by nature. Traces of volcanic material trapped in ice show when big eruptions happened, and unusually narrow tree rings show years when plants grew badly. Put together, they link the eruptions to spells of sudden cold.

Cold was especially dangerous in Scandinavia. Farmland there was scarce and the growing season short, so the margin for error was much narrower than around the Mediterranean. Farmers needed enough warmth to bring in the harvest before autumn, and they had to gather fodder to keep their animals alive through winter. A poor growing season threatened both. Repeated failures could make survival nearly impossible. Price notes that some scholars have estimated the combined effect of the eruptions at a 50 per cent death rate — not everywhere in Scandinavia, but in some places. "In social terms, that's catastrophic," he says.

Scandinavians were already living through upheaval at the time. The Roman Empire was breaking apart, and although Scandinavia had never been a Roman province, its people were tied into the empire's trade and fighting. Settlements and cemeteries declined. Soldiers who had served abroad came home with skills that helped them become local warlords. Communities were dealing with all of that when the eruptions began.

The eruptions themselves are not in doubt. What they did to particular communities is harder to pin down, and harder still is proving that a story told centuries later grew out of them. Price's idea is a suspicion, not a settled fact. Even so, it offers a striking possibility: that the mighty winter which ends the Norse world is a folk memory of a real winter that once fell on the north.