Ed West considers just how much human history has been shaped by vulcanology, including one near-extinction event for the human race:
A huge volcano has erupted in Iceland and it looks fairly awesome, both in the traditional and American teenager senses of the word.
Many will remember their holidays being ruined 13 years ago by the explosion of another Icelandic volcano with the epic Norse name Eyjafjallajökull. While this one will apparently not be so disruptive, volcano eruptions are an under-appreciated factor in human history and their indirect consequences are often huge.
Around 75,000 years ago an eruption on Toba was so catastrophic as to reduce the global human population to just 4,000, with 500 women of childbearing age, according to Niall Ferguson. Kyle Harper put the number at 10,000, following an event that brought a “millennium of winter” and a bottleneck in the human population.
In his brilliant but rather depressing The Fate of Rome, Harper looked at the role of volcanoes in hastening the end of antiquity, reflecting that “With good reason, the ancients revered the fearsome goddess Fortuna, out of a sense that the sovereign powers of this world were ultimately capricious”.
Rome’s peak coincided with a period of especially clement climatic conditions in the Mediterranean, in part because of the lack of volcanic activity. Of the 20 largest volcanic eruptions of the last 2,500 years, “none fall between the death of Julius Caesar and the year AD 169”, although the most famous, the eruption of Vesuvius in AD 79, did. (Even today it continues to reveal knowledge about the ancient world, including a potential treasure of information.)
However, the later years of Antiquity were marked by “a spasm” of eruptions and as Harper wrote, “The AD 530s and 540s stand out against the entire late Holocene as a moment of unparalleled volcanic violence”.
In the Chinese chronicle Nan Shi (“The History of the Southern Dynasties”) it was reported in February 535 that “there twice was the sound of thunder” heard. Most likely this was a gigantic volcanic explosion in the faraway South Pacific, an event which had an immense impact around the world.
Vast numbers died following the volcanic winter that followed, with the year 536 the coldest of the last two millennia. Average summer temperature in Europe fell by 2.5 degrees, and the decade that followed was intensely cold, with the period of frigid weather lasting until the 680s.
The Byzantine historian Procopius wrote how “during the whole year the sun gave forth its light without brightness … It seemed exceedingly like the sun in eclipse, for the beams it shed were not clear”. Statesman Flavius Cassiodorus wrote how: “We marvel to see now shadow on our bodies at noon, to feel the mighty vigour of the sun’s heat wasted into feebleness”.
A second great volcanic eruption followed in 540 and (perhaps) a third in 547. This led to famine in Europe and China, the possible destruction of a city in Central America, and the migration of Mongolian tribes west. Then, just to top off what was already turning out to be a bad decade, the bubonic plague arrived, hitting Constantinople in 542, spreading west and reaching Britain by 544.
Combined with the Justinian Plague, the long winter hugely weakened the eastern Roman Empire, the combination of climatic disaster and plague leading to a spiritual and demographic crisis that paved the way for the rise of Islam. In the west the results were catastrophic, and urban centres vanished across the once heavily settled region of southern Gaul. Like in the Near East, the fall of civilisation opened the way for former barbarians to build anew, and “in the Frankish north, the seeds of a medieval order germinated. It was here that a new civilization started to grow, one not haunted by the incubus of plague”.
