Monday, July 31, 2017

Then Iceland Struck Back

The Economist of 22 July 2017 reports an intriguing piece of historical detective work that ties together an early medieval famine, a buried volcano, ice cores, and tree-ring isotopes.

Shortly after the death of Charlemagne, western Europe experienced three years (821-24) of terrible weather: hard winters, frozen rivers, failed crops, and famine. The Frankish monk Paschasius Radbertus recorded these “years without summer” but could only attribute them to the wrath of God. Environmental scientists tend to associate “summerless” years not with divine displeasure but with volcanic eruptions, and a large one apparently occurred in this period. Ice core extractions from Greenland show elevated levels of sulfate particles, a marker for volcanism (which ejects sulfur dioxide into the atmosphere), during the third decade of the ninth century.

Identifying the specific volcano responsible for Radbertus’s famine would seem impossible, but in 2003 serendipity provided an important clue. Flooding in southern Iceland uncovered the remains of an old forest in southern Iceland, 20 miles from the Myrdalsjokul glacier. 2,200 feet beneath that glacier lies Katla, a volcano that periodically erupts through its ice cover, producing powerful floods. Such a flood likely killed the now-buried forest: the ancient trees, which had all been knocked down at the same time, pointed away from Katla, indicating that some force from that direction had felled them. 

According to Ulf Buntzen (Cambridge), the trees’ rings give a precise date for their demise: 47 years after 775 CE, when an unknown event (probably heightened solar activity) deposited high levels of Carbon-14 isotope in tree rings worldwide. The flood thus took place in 822, soon after the start of the frigid weather observed by our Frankish monk, and during the period of elevated sulfate levels found in the Greenland ice. This is as close to absolute proof of a volcanic eruption in Iceland as one can get in the absence of on-the-spot observers, who wouldn’t arrive on the island for another half-century.

Iceland has suffered a great deal from outside illnesses and calamities, but one should recall that it is contributed to one or two of its own (crop failures, disrupted air travel, bad music) over the centuries. The world is a small place, and small places can exert an outsized influence on it.

Monday, July 03, 2017

Pity Poor Iceland (1707 Edition)

When I teach my students about the impact of Old World diseases on Native Americans, I stress that the lethality of these illnesses resulted from Indians’ geographic isolation, not their genetic background or lack of medical knowledge. Without prior experience of maladies like measles and influenza, indigenous peoples became vulnerable to the “virgin-soil” effect, where no-one had acquired immunity to a disease and thus everyone in an infected community became sick. Any similarly isolated population, even a European one, could suffer a deadly virgin-soil epidemic. As Exhibit A, I present the case of Iceland. Hard winters (especially during the Little Ice Age) and rough northern seas cut Icelanders off from the European mainland, allowing them to develop their distinctive and venerable culture*, but also allowing generations to grow up without exposure to crowd diseases.

In 1707 this led to disaster. A ship from the mainland brought in smallpox, one of the most dangerous Eurafrican maladies. Smallpox is airborne and highly contagious in confined spaces, like the smoky interiors of Icelandic farmhouses. It kills around a quarter of those who become infected without modern medical treatment - more if they lack food, water, and warmth. Those who survive usually suffer permanently disfiguring scars on their faces, hands, and feet, the result of the weeping pustules that characterize the final stages of the disease. Relatively few Icelanders bore these scars in 1707. The island had experienced several smallpox epidemics in the past, but the last outbreak ended in 1670, so almost no-one under 40 had an immune system that could recognize the disease.

The disease spread slowly, but relentlessly, through the countryside. By 1709, when the last cases of sickness were recorded, variola (the virus that causes smallpox) had killed 12,000 people, nearly one-quarter of Iceland’s population. Most likely there were enough survivors of the earlier outbreak to take care of the sick, which kept the death rate slightly below its usual pre-modern level. Still, so great a loss, especially of children and young people, must have been a heavy blow to so small and rural a society. The only benefit was the immunity conferred to the survivors, which made the next few incidences of smallpox less lethal.

Visiting officials kept a good record of the 1707-09 epidemic, but this probably didn't produce major changes in Icelanders' behavior. Epidemics rarely do, somehow. In any case, warnings about the dangers of smallpox would not have helped the survivors' grandchildren when they faced the next great disaster in their island's history, a concatenation of natural disaster, famine, and disease that slaughtered cattle, poisoned the land, and left 10,000 people dead. 

Arguably, Iceland would have been better off if the eighteenth century had never happened.

Sources: Alfred Crosby, "Virgin Soil Epidemics as a Factor in the Aboriginal Depopulation in America," William and Mary Quarterly, Third Series, 33 (1976): 289-299; J.N. Hays, Epidemics and Pandemics (ABC-Clio, 2005), 131-133

Image above by Diego Delso (, License CC-BY-SA.

* Icelanders preserved to the present day their medieval language, their sagas, and their mythology, including the famous Norse myths that became lost or corrupted on the mainland.