In A Nutshell
Something major happened on Earth 1,478 years ago. From 535–536, the Northern Hemisphere experienced a period of extreme cooling. People all over the world recorded extreme low temperatures, crop failure, drought, and a lack of direct sunlight due to a dense fog and cloud cover. Samples from around the world have provided clues that the event may have been caused by a large volcanic eruption or the impact of a comet or meteorite, but with no human record of any similar events, the direct cause remains a mystery.
The Whole Bushel
In the years 535–536, the world experienced a period of extreme cooling that was caused by one of the greatest natural disasters in history. The event blotted out light and heat from the Sun, which directly or indirectly led to climate change, famine, migration, war, crop failure, and political change. At this time in history, the bubonic plague spread across the world and greatly damaged the Roman Empire, which would lose half its territory over the next century.
During these years of extreme weather, people all over the world recorded extreme low temperatures, including crop failure, a drought in Central America, a strange yellow dust over Asia, and a dense fog over the Middle East, China, and Europe. Tree ring analysis has found little growth for the year 536 in Ireland, Sweden, Finland, California, and Chile. Ice core samples from Greenland and Antarctica have provided evidence for a large sulfate deposit in 535. There is also evidence for a decline in tree growth from the year 542.
The tree ring analysis and ice core evidence points to the fact that the cooling was probably caused by a large volcanic eruption or impact of a comet or meteorite. Many people have attempted to explain the occurrence and feel the event was caused by the eruption of Rabaul in Papua New Guinea, the Indonesian volcano Krakatoa, or the Tierra Blanca Joven eruption of the Ilopango caldera in Central El Salvador. Others feel ice core samples provide evidence that the Earth experienced a comet impact and massive terrestrial debris ejection. The true cause of the cooling remains a geological mystery that continues to be investigated by the scientific community.
Show Me The Proof
New ice core evidence for a volcanic cause of the A.D. 536 dust veil
A comet impact in AD 536?
Catastrophe: An Investigation into the Origins of Modern Civilization, David Keys
Climate Change and the Fall of the Late Roman Empire