What’s the News: Climate change may have sparked the demise of early Viking settlements in Greenland, according to a new study published online in the Proceedings of the National Academy of Sciences, when temperatures cooled rapidly over several decades. Around the time the Vikings disappear from the island’s archaeological record, temperature appears to have plunged. Nor were the Vikings the only people in Greenland whose fortunes rose and fell with the average temperature, the study suggests. Earlier cold spells may have played a role in the collapse of two previous groups on the island. How the Heck:
To reconstruct the area’s climate, the researchers took mud cores from two lakes in western Greenland. Then, they measured the levels of alkenones, fats made by algae, left behind in the mud. Since how much algae blooms depends on the water temperature, and the water temperature varies with the air temperature, this measurement lets scientists work backward to figure out what the past climate was like.
Over the past 5,600 years, the researchers found, the arrivals and departures of three groups coincided with major, rapid temperature changes.
The Saqqaq people, who first came to Greenland about 4,500 years ago, disappeared around 850 BC, when temperatures quickly cooled. At the same time, the Dorset people came to the island. As Inuits from the Canadian Arcitic, the Dorset were prepared for the cold, with a technological arsenal that included snow-cutting knives for building igloos.
About 2,000 years ago, the Dorset, too, left the island, though the reason remains unclear. It could have something to do with the climate quickly warming then rapidly cooling at about that time. “It is possible that it got so cold they left, but there has to be more to it than that,” climate change researcher William D’Andrea, the study’s lead author, said in a prepared statement.
The Norse Vikings arrived in Greenland around 980 AD, during a 300-year-long warm period. Starting around 1100, however, the climate cooled rapidly. Average temperature dropped 4 degrees Celsius (7 degrees Fahrenheit) in only 80 years. Since the Norse—Viking fame aside—were largely farmers, this drop in temperature likely hit them hard. They began to leave Greenland shortly thereafter, and by the mid-15th century their settlements lay abandoned.
What’s the Context:
While the archaeological record has shown when these cultures came and went from Greenland, it has provided relatively little information as to why. This study backs up the archaeological finds and shows that climate could be a major factor in the rise and fall of these groups.
It’s likely that other events and circumstances played a role, too. The Vikings, for instance, were grappling with isolation from European trade (and the much-needed resources it supplied), soil erosion, and competition from Inuit peoples.
The Future Holds:
Greenland today is undergoing rapid climate change as the Arctic warms. This warming will likely have a range of effects, from a longer growing season to a more quickly melting ice sheet. “The Arctic is undergoing major changes,” D’Andrea told Scientific American. “Just like in the past, some people will benefit and others will lose out.”
Reference: William J. D’Andrea, Yongsong Huang, Sherilyn C. Fritz, & N. John Anderson. “Abrupt Holocene climate change as an important factor for human migration in West Greenland.” PNAS Early Edition, May 30, 2011. DOI:10.1073/pnas.1101708108
Image: Greenland from the air; Wikimedia Commons / Túrelio