A volcano froze crops worldwide in 1453

According to the record of the 1452/1453 mystery eruption, a volcano erupted somewhere on Earth powerful enough to inject about 11 megatons of sulfur into the stratosphere — "roughly one-third that of the 1815 eruption of Mount Tambora" — and no one knows which volcano it was. Ice cores in Greenland and Antarctica record the chemical spike it left in the atmosphere, but no telltale volcanic ash has ever been found to pin down the source.

The fallout shows up in records worldwide. Chinese chronicles from 1453 describe how "several feet of snow fell in six provinces; tens of thousands of people froze to death," and how the following year "it snowed for 40 days south of the Yangtze River." Tree rings across Europe and North America show frost damage and stunted growth.

The eruption coincided with the fall of Constantinople in May 1453. As the Ottomans besieged the city, a strange red glow was seen playing over the Hagia Sophia; historians now think it was sunlight reflected off high clouds of volcanic ash. Similar false fire alarms were reported worldwide after the eruption of Krakatoa in 1883.