The Eldgjá eruption and the Christianisation of Iceland

A series of Earth-shattering volcanic eruptions in Iceland during the Middle Ages may have spurred the people living there to turn away from their pagan gods and convert to Christianity, a new study finds.

The discovery came about thanks to precise dating of the volcanic eruptions, which spewed lava about two generations before the Icelandic people changed religions.

Codex Regius

But why would volcanic eruptions turn people toward monotheism? The answer has to do with the “Vǫluspá,” a prominent medieval poem that predicted a fiery eruption would help lead to the downfall of the pagan gods, the researchers said.

Historians have long known that the Vikings and Celts settled Iceland in about A.D. 874, but they were less certain about the date of the Eldgjá lava flood, the largest eruption to hit Iceland in the past few millennia. Knowing this date is crucial, because it can tell scientists whether the eruption — a colossal event that unleashed about 4.8 cubic miles (20 cubic kilometers) of lava onto Greenland — impacted the settlement there, the researchers said.

To investigate, the researchers examined ice core records. Their results showed that the eruption took place less than 100 years after people settled the island. The volcano began gushing lava in the spring of A.D. 939 and lasted, at least episodically, until the autumn of 940, the researchers said.

a) Locations of Eldgjá, the NEEM drill site and medieval documentary evidence referenced in the text covering 939–942 CE. b) Section of the 75-km-long Eldgjá eruption fissure at Ófærufoss. c) The Codex Regius; finger points to beginning of stanza 57 of Vǫluspá

“This places the eruption squarely within the experience of the first two or three generations of Iceland’s settlers,” study lead researcher Clive Oppenheimer, a professor of volcanology at the University of Cambridge, in England, said in a statement. “Some of the first wave of migrants to Iceland, brought over as children, may well have witnessed the eruption.”

The finding matches medieval chronicles from Ireland, Germany and Italy that noted the spread of a haze in 939. Moreover, the tree-ring data revealed that in A.D. 940, the Northern Hemisphere had one of its coldest summers in the previous 1,500 years — a cold shift consistent with the release of large amounts of volcanic sulfur into the atmosphere, the researchers said.

“In 940, summer cooling was most pronounced in Central Europe, Scandinavia, the Canadian Rockies, Alaska and Central Asia, with summer average temperatures 2 degrees Celsius [3.6 degrees Fahrenheit] lower,” co-researcher Markus Stoffel, a professor in the Department of Earth Sciences at the University of Geneva in Switzerland, said in the statement.

Suffering followed, with hard winters and drought in the spring and summer. Locusts invaded, and livestock died. “Famine did not set in everywhere, but in the early 940s, we read of starvation and vast mortality in parts of Germany, Iraq and China,” said study co-researcher Tim Newfield, an environmental historian at Georgetown University, in Washington, D.C.

However, no texts from that period survive from Iceland, the volcano’s homeland.

A mere two generations after the Eldgjá eruption, in about A.D. 1000, the people of Iceland formally converted to Christianity. And it likely had to do with the “Vǫluspá,” the researchers said.

The “Vǫluspá” was written after the eruptions, in about A.D. 961. It describes how an eruption and meteorological events would mark the end of the pagan gods, who would be replaced by one, singular god, the researchers said.

Part of the poem explains how “the sun starts to turn black, land sinks into sea; the bright stars scatter from the sky … flame flies high against heaven itself,” according to a translation.

Considering Eldgjá’s eruptions date to before the poem was written, Icelanders who experienced the fiery spectacle likely looked back at the events and wrote the poem, “with the purpose of stimulating Iceland’s Christianization over the latter half of the 10th century,” the researchers wrote in the study, published online in the journal Climate Change.



An Ice Core Reveals How Profoundly The Black Death Changed Medieval Society

In the year of the Lord 1347, the Black Death arrived in Europe. Introduced by merchants coming from Asia, the plague, caused by the bacterium Yersinia pestis, spread quickly. Following trading routes, in just six years this incurable disease killed 25 million people, one-third of the population on the continent. Entire villages were wiped out, some cities lost 80% of their citizens. The plague was followed by famine. Thomas Basinus (1412-1491), bishop of Èvreux and later historian, notes that ‘many peasants fled or died so that many fields remained uncultivated or there was nobody left to care.’ In the cities, overpopulation and poor hygiene helped to spread the plague, rivers were used to dispose of the many corpses, contaminating the water. Riots of desperate people were common, like in 1323 in Flanders and in 1358 in France. Many believed, as one witness testified, that the end of the world had arrived.

The Triumph of Death is a painting by Pieter Bruegel the Elder, painted c. 1562 it was inspired by the waves of the Black Death plaguing the 14th century.

The dramatically reduced population had, however, a surprisingly beneficial effect on the environment. The pollution of the air dropped to a historic low.

Analyzing a 236 feet long ice core recovered from a glacier in the Swiss-Italian Alps, a team of scientists from Harvard University was able to reconstruct the concentration of lead in the air over Europe for the last 2,000 years. The research with the title ‘Next-generation ice core technology reveals true minimum natural levels of lead (Pb) in the atmosphere: Insights from the Black Death,’ was published in the open access journal GeoHealth.

Atmospheric circulation transported the lead from the lowlands into the Alps, where it was washed out from the atmosphere by rain and snow. The snow, accumulating mostly during winter, partially melts and changes over the summer into ice, forming single layers, as found in a glacier. By analyzing the concentration of elements in the single layers, it is possible to create an annual record of the atmospheric deposition. One significant spike can be found around 1349-1353 when the measured concentration of lead dropped far below the average value of 10^2 nanogram of lead per liter air. Even today, after the introduction of unleaded fuel in the 1980s, the concentration of lead in the air is still 10 times higher as in 1350.

Reconstructed lead concentration in the last 2,000 years and most important mining districts. Image Source & Credit MORE et al. 2017. CC BY-NC-ND 4.0

In medieval times, lead was used for roofing of large buildings such as cathedrals, water pipes, but especially for dishes and glazed pottery valued by the rich. The most important lead ore is galena. As galena also contains silver, it was widely mined (silver, lead, and copper were the most important metals in medieval Europa). The most productive mines were found on the British island, South Italy, the Harz mountains with Freiberg in Saxony and Kutna Hora in Bohemia. We know of contemporary records of the silver medieval monarchs received as royalties, that the mines of  Freiberg and Kutna Hora alone provided 20 tons of silver and 100 tons of lead per year. To get this amount,  it was necessary to mine and process an almost 2,000 times larger quantity of rocks and ore. The Black Death impacted mining in two ways. The miners and workers died in great number, and many mines were abandoned. As the population died, including the rich people, the demand for lead also dropped.

The Black Death was so deadly, mining for lead virtually stopped and no lead dust, coming from both mining as smelting, was dispersed into the environment. As the atmosphere became cleaner, the concentration of lead deposited in the glaciers of the Alps dropped.

Entrance to a medieval mine in the Alps, dated around 1530.

The Black Death had a disastrous impact and yet helped to create modern Europe. Plagued previously by overpopulation and poverty, Europe could reinvent itself after the Black Death made the old political system obsolete. Many peasants at the time were virtually slaves, owned by the rich landlords. As the landlords were gone, many people were free to choose where and when to settle. The surviving landlords, in desperate need of somebody to take care of their properties,  agreed to lower the taxes and more privileges were granted to farmers. Wages everywhere increased, as healthy workers were rare, and the land became cheaper. Many previously poor people managed to achieve some wealth. Authorities even tried to forbid the use of fur in clothing, a privilege reserved only to the aristocracy in former times, but now common. Political and social independence was now possible and a new class rose from the ashes of the old society — the free citizen. A new human being for a new epoch, as the Renaissance was later seen by historians. However, even after 1353, the Black Death didn’t completely disappear. Almost once in a decade, a smaller outbreak was reported, but improved hygiene in the cities, quarantine procedures, and an acquired genetic immunity of the survivors reduced the risk of infection significantly.

This societal development can also be seen in the studied ice core. Just some years after the plague of 1347-1353, the concentration of lead significantly increased, approaching values seen before the Black Death. The European mining industry experienced a boom in the 15th and 16th century, testified also by many active mines found now also in the Alps. Only recently the concentration of lead started to drop again, in response to efforts to ban this toxic element from daily use and improved environmental regulations. However, it is still an important metal, mostly used for batteries in the automobile industry.