Level 2: Intermediate
In the middle of the 6th century, a mini ice age that lasted 125 years and an outbreak of plague plunged the world into chaos. One of the key events that helped to kick it all off was the massive eruption of a volcano somewhere in the southern hemisphere. Now we may know when and where it happened.
Huge volcanic eruptions fling so much ash and debris into the atmosphere that sunlight is partially blocked out, which can cool Earth and encourage more ice to form at the poles. That reflects more sunlight, further cooling the planet. It’s long been thought that the coincidental eruption of multiple volcanoes between AD 536 and AD 547 kick-started what’s known as the Late Antique Mini Ice Age.
Antarctic ice core data suggest two very big eruptions at the time: one around AD 536 and one around AD 540.
Robert Dull at California Lutheran University and colleagues have now used tree trunks to show that the latter eruption appears to have occurred at the Ilopango volcano in El Salvador. The team found the remains of three trees that “witnessed” the eruption. Two of them were killed by the event.
Radiocarbon dating on multiple tree rings inside the trunks revealed their age – the trees died between AD 503 and AD 545. Evidence from ash deposits in nearby soil also helped to confirm that a gigantic eruption happened around this time, most likely in late AD 539 or AD 540.
Researchers still haven’t identified which volcano was behind the AD 536 eruption, but it too is thought to have been in the northern hemisphere.
The cooling effects of the Ilopango eruption could easily have lasted a decade and perhaps longer, says Dull.
Michael Sigl at the University of Bern agrees: “I think the Late Antique Little Ice Age was started by these eruptions here and prolonged by others.”