ENVIRONMENT

The Veiled Sun

536 CE

History · Middle Ages · Holocene · Meghalayan

In 536 CE the sun dimmed for months on end; Byzantine witnesses wrote that it shone like the moon. Tree rings and ice cores name the cause, a great volcanic eruption, with others following in 540 and 547; together they opened more than a century of cooling across the Northern Hemisphere. Harvests failed under the veil, and within five years the Justinianic plague was killing across the same weakened world; from Rome's eastern heir to Sasanian Persia, empires entered the crisis together.

Why it matters

536 has been called the worst year to be alive, and the science behind that verdict is the point: an event known for fifteen centuries through chronicles alone is now read year by year in wood and ice, eruption by eruption. Volcanic shock, famine, pandemic and political crisis are entangled here within a few years, the same braid this timeline follows from the 4.2 ka drought to Tambora. The sky can change history in a season.

Dating & uncertainty

Tree rings across the Northern Hemisphere record the sharpest cooling between mid-July and early August 536. Eruptions in 536, 540 and 547 opened a cold phase, prolonged by ocean and sea-ice feedbacks and by a solar minimum, that is now called the Late Antique Little Ice Age and ran to about 660. Wood anatomy does not find the same signature in southern trees, and the reason is unsettled: little volcanic aerosol may have reached the southern extratropics, or the cooling there was damped, or it fell outside the growing season.

Sources

1. Büntgen et al. (2016), Nature Geoscience · Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 ADdoi:10.1038/ngeo2652
2. Büntgen et al. (2022), Science Bulletin · Global wood anatomical perspective on the onset of the Late Antique Little Ice Age (LALIA) in the mid-6th century CEdoi:10.1016/j.scib.2022.10.019
3. Helama et al. (2018), Scientific Reports · Volcanic dust veils from sixth century tree-ring isotopes linked to reduced irradiance, primary production and human healthdoi:10.1038/s41598-018-19760-w

Our species’ history as one day

23:53:116 min 49 s before midnight

if the 315,000 years of Homo sapiens were compressed into a single day