AD 536

Volcanic winter of 536

The atmospheric veil of 536 dims the sun and disrupts the seasons

Cassiodorus wrote that people cast no shadows at noon even though the sun stayed visible.

A year of weak sunlight

During 536, Procopius recorded that the sun gave light without its customary brightness and resembled an eclipse for the whole year. His account concerns the Mediterranean world; it does not place the observation specifically in Constantinople.

Writing from Ostrogothic Italy, Cassiodorus described a bluish sun, absent midday shadows, weak heat, a cold and dry growing season, hardened fruit and bitter grapes. He ordered stored produce used against the scarcity he expected.

The Irish record compresses the year into three words — “failure of bread” — though that entry survives in a much later compilation whose annalistic dating is not exact.

What the ice and the trees record

Revised ice-core chronologies identify major volcanic aerosol loading associated with the sixth-century cooling, and tree rings register exceptional Northern Hemisphere cooling beginning in 536. Multiple tree-ring reconstructions rank 536, 1453 and 1601 as the coldest Northern Hemisphere summers of the Common Era.

The volcano itself has not been identified, and neither has its latitude. A 2008 ice-core study favoured a near-equatorial eruption; later volcanic-glass evidence pointed to Iceland, and other work has considered North America. The timing is loose too: the eruption may have occurred in late 535 or early 536, and some ice-core chronologies place the relevant sulfate layer at 533–534, give or take two years.

The 540 eruption was separate

A separate, stronger tropical eruption around 540 prolonged the cooling, and evidence produced by that later event should not be attributed to 536.

Sources

Researched 23 Aug 2026 8 sources 2 audit passes, 2 issues open Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree about when this happened.

What the sources leave uncertain

The atmospheric anomaly is securely dated to 536, but the eruption may have occurred in late 535 or early 536; no exact start day is known.
The 536 signal points to a Northern Hemisphere extratropical source, but proposed Icelandic and North American identifications remain tentative.
A separate, stronger tropical eruption around 540 prolonged the cooling. Evidence produced by that later eruption should not be attributed automatically to the 536 event.
The extent and duration of the proposed Late Antique Little Ice Age are debated: one reconstruction extends it to about 660, while another finds widespread Eurasian cooling ended no later than the 570s.