(ORDO NEWS) — For more than 450 years, Norse settlers from Scandinavia have lived – sometimes even prospered – in southern Greenland. Then they disappeared.
Their mysterious disappearance in the 14th century was attributed to a variety of reasons – from a sharp drop in temperature and poor land use to plague and pirate raids. Now researchers have discovered another factor that could have sealed the fate of the settlers: drought.
The Vikings raided, traded and eventually established Nordic settlements throughout northwestern Europe, including in Iceland.
According to Icelandic legend, an explorer named Eric the Red sailed west around 985 BC and founded two settlements in southern Greenland. During its heyday, about 3,000 Norwegian farmers raised cattle, sheep and goats on the island.
In a new study, Boyang Zhao, a paleoclimatologist at the University of Massachusetts Amherst, and colleagues analyzed mud from a lake bed in southern Greenland looking for clues about the climate that Norse settlers lived in between 985 and 1450. BC. The lake lies within one of two settlements (East Settlement), next to a cluster of stone ruins that were once houses and cowsheds of the Norse.
Last year, a team of researchers showed that the biochemistry of bacteria in a lake changes with temperature.
For the new study, they recovered the remains of long-extinct microbes from layers of mud at the bottom of the lake, which were radiocarbon dated. Tracking changes in the chemical composition of bacteria over time, they reconstructed the temperature in the past.
Although temperatures fluctuated during the period of Norwegian occupation, the researchers found no long-term cooling trend. “When I saw these temperature records, I was very surprised,” Zhao says, given the widespread belief that lower temperatures made it difficult to care for livestock and contributed to the death of the settlement.
The water availability data told a different story. To study this feature, the team examined hydrogen isotopes in plant remains buried in lake silt. When plants lose water through evaporation in dry weather, their leaves are enriched with the heavy isotope of hydrogen, deuterium.
By measuring the deuterium content in leaf remains from lake silt layers, the researchers found that the climate of southern Greenland became increasingly dry during the Norse period, they report today in the journal Science Advances.
According to Zhao, if droughts were more frequent, the Norwegians would not be able to grow enough grass to keep their livestock from starving during the long, cold winters.
Thomas McGovern, an archaeologist at Hunter College, says it’s plausible that the Norwegians had to deal with drought. Excavations on Norwegian farms have unearthed evidence of irrigation canals to draw water and distribute it over a wide area, he notes.
Today’s farmers in Greenland also face water shortages, said Zhao, who spoke to locals while working in the field. “I asked them: What is the most important problem for you today? They said that if there is not enough rain in the summer, they will not get enough grass to feed their animals.”
Greenland has been hit by several severe droughts in recent years. “About 2015 it was very dry – we had rain in June and then another rain in August,” says Elna Jensen, who farms in the Narsaq area of Greenland, close to the lake that Zhao’s group was studying.
But Norwegian and modern farming are different, warns Christian Madsen, deputy director of the National Museum and Archives of Greenland. For example, many modern farmers drain and fertilize their land to increase productivity, but this makes the land more vulnerable to the effects of drought.
It’s also important to understand that the Norwegians were really trying to adapt to Greenland’s changing environment, says McGovern. Archaeological finds show that they began to consume more marine food, including seal meat, as farming became increasingly difficult.
But they disappeared anyway, and McGovern argues that social factors may have played a key role too. The Norwegians made long and dangerous voyages to the waters off northwestern Greenland, where they hunted walruses for ivory to sell on the European market.
Ivory was a source of wealth and power for the local elite, but by diverting some of the working-age population from food production as conditions deteriorated, walrus hunting may have contributed to the settlement’s demise.
“We can see looking back at 20:20 how they could have survived, but they didn’t,” says McGovern. “It was a society that, in some respects, chose to fail.”
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