Did drought drive the Vikings out of Greenland?

Did drought drive the Vikings out of Greenland?

View of abandoned settlement structures of the former European inhabitants on Greenland. © RUBEN RAMOS/iStock

For almost 500 years, the Vikings had defied the challenges on the barren island – why did the settlements on Greenland come to an end in the 15th century? New indications of the local climate development in the period in question now suggest that increasing drought was causing problems for the settlers and not the cold, as previously assumed. Presumably, the livestock could no longer be adequately fed and one of the Greenlanders’ livelihoods broke away, the researchers explain.

According to tradition, the famous navigator Erik the Red brought the first settlers from Iceland to the southern tip of Greenland in 986. Among other things, the Vikings were after the tusks of the local walruses: the settlers were able to supply medieval Europe with valuable ivory. Livestock farming was an important basis for their diet on the barren island: the settlers cleared the land of shrubs, creating pastures for their cattle, sheep and goats. In this way, a flourishing and initially stable colony was finally able to develop. But towards the end of the Middle Ages things went downhill – the settlements were gradually abandoned. In the 15th century, the traces of the last European inhabitants of the island are lost. After that, only the indigenous Inuit lived in Greenland.

What led to the end?

What led to the sinking is still unclear today. It was probably a mixture of different factors. Declining demand for walrus ivory, the spread of the Inuit, and the plague may have played a role, previous studies have suggested. Climatic change is also considered to be a fundamental factor. It was previously assumed that the decline was related to the beginning of the so-called Little Ice Age – a period of exceptionally cold weather at the end of the Middle Ages. However, as the researchers led by Raymond Bradley from the University of Massachusetts Amherst explain, there was no data on the exact location of the Viking settlements, only from areas further north in Greenland. “So we wanted to take a closer look at how the climate near the Nordic farms has changed,” says Bradley.

The researchers examined sediment cores from a lake that borders a former Viking farm and is close to one of the largest groups of farms in the eastern settlement area of ​​the former Greenland colony. The sample material covered the period of the last 2000 years. Their analyzes focused on two markers in the layers: one is a lipid called BrGDGT, which is formed by bacteria. The researchers explain that it can provide clues to past temperature conditions. “If the records are complete enough, you can directly link the changing structures of the lipids to temperature changes,” says co-author Isla Castañeda. The second marker is the remains of waxy coatings of plant leaves in the sediment. They can serve as an indicator of how wet or dry conditions at a site once were.

Too dry instead of too cold

As the team reports, the surprising findings were: “We found that the temperature changed little during the Greenland settlement era. However, we noticed an increasing drought over time,” says first author Boyang Zhao. As he and his colleagues explain, this arguably posed a greater threat to human survivability than the small changes in temperature. Because a drier climate probably affected grass production, which was particularly important for cattle overwintering. In Greenland, farmers were already pushing the northern limits of what was possible. Under these circumstances, the consequences of droughts would have been severe, the scientists say.

Among other economic and social stresses, the increasing drought may have destabilized the system to the point where settlements could no longer be sustained, Bradley and his colleagues conclude. “The study changes our understanding of European history and underscores the importance of continuing to study how environmental factors can influence human society,” the University of Massachusetts Amherst concludes.

Source: University of Massachusetts Amherst, Science Advances, doi: 10.1126/sciadv.abm4346

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