One Volcano Made 536 the Year the Sun Went Out

Historians have been calling this period the Dark Ages for centuries. Turns out they were being more accurate than they knew.

In 536, a mysterious fog descended over Europe, the Middle East and parts of Asia. For 18 months, day and night, the sun dimmed to something closer to a moon. Summer temperatures dropped 1.5°C to 2.5°C (2.7°F to 4.5°F), triggering the coldest decade in 2,300 years. Snow fell in China that summer. Ireland recorded a failure of bread harvests from 536 to 539. Then, in 541, bubonic plague arrived at the Roman port of Pelusium in Egypt, spread rapidly, and killed between one-third and one-half of the eastern Roman Empire's population, accelerating its collapse. All of that from one event, in one year.

The culprit, long debated, was pinned down with unusual precision. A team led by Harvard historian Michael McCormick and glaciologist Paul Mayewski drilled a 72-meter ice core from the Colle Gnifetti Glacier in the Swiss Alps, a frozen archive of more than 2,000 years of atmospheric history. Using a laser to carve 120-micron slivers of ice, each representing just days or weeks of snowfall, and analyzing roughly 50,000 samples per meter, researchers found two microscopic particles of volcanic glass in ice from the spring of 536. Chemical fingerprinting linked those particles to Iceland. A massive eruption there had sent ash across the Northern Hemisphere. Two more eruptions followed, in 540 and 547. Then came the plague. The economic stagnation lasted until 640.

How do we know 640 is when things finally turned around? Lead in the air. Silver was smelted from lead ore, and a spike in atmospheric lead in 640 signals the return of silver mining and, for the first time, the rise of a merchant class.

The volcano caused the darkness. The ice remembered it. The lead announced the world's recovery.

Read the full story at Science, November 15, 2018

Hot Take: A reminder from the year 536: things can get much, much worse.