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In Norway’s Lofoten Islands, archaeologists unearthed one of the largest Viking buildings ever found. The massive 83-meter longhouse, discovered in what is now the town of Borg, was an ostentatious display by powerful chieftains who ruled what at first glance seems to be a marginal area—a cluster of islands just shy of the Arctic Circle. For more than 2,500 years, the people of the Lofotens grew barley and wheat and pulled cod from the frigid North Atlantic. The Lofotens were at the center of Viking politics, yet at the very edge of where the brisk northern climate made farming possible. This makes the Lofotens an ideal place to explore how climate change affected Viking life.
Each year, the landowners in the Lofotens would make critical decisions: which crops to plant, how much livestock to raise, how much cod to fish, whether to send ships to raid the wealthy European villages to the south. In weighing all of these options, minor shifts in climate could be a major factor, says William D’Andrea, a paleoclimatologist at Columbia University’s Lamont-Doherty Earth Observatory in New York. Over the next three years, D’Andrea and Nicholas Balascio, a paleoclimatologist at the College of William and Mary in Virginia, will be working to reconstruct the effects of short-term climate variability on the islands.
The study is just getting underway, but D’Andrea and Balascio think that by examining everything from plant pollen to animal waste, as recorded in lakebed sediments, they can gain an understanding of how the islands’ people and their activities might have changed to adapt to the changing climate. The researchers will be looking for biomarkers—molecules unique to specific animals or plants—to see how much and what types of livestock and crops were being raised from year to year.
“These marginal communities can be very sensitive to these natural environmental changes,” Balascio says. For instance, the changing climate may have caused the Vikings to move their farms to new locations to take advantage of the best conditions for their fields.
Falling sea levels provided another challenge for the Lofoten Vikings. The Lofoten Islands, like much of Scandinavia, are to this day rebounding from the loss of the massive ice sheets that covered the land during the last ice age. This phenomenon, called isostatic rebound, is causing the islands to rise, effectively making the sea level fall. This means that boathouses built at the water’s edge could be stranded inland a few decades later.
The locations of harbors deep enough to accommodate the Vikings’ famed sailing ships also changed over time. The falling sea may have made the harbor near Borg inaccessible to large ships and played a role in why the longhouse was abandoned. While these changes are geological rather than climatological, the ways the Vikings adapted to falling seas is also a focus of D’Andrea and Balascio’s project.
But on the climate front, one particularly important variable driving the seasonal fortunes of the Lofoten Vikings was a recurring pattern known as the North Atlantic Oscillation (NAO). The NAO is a set of rhythms that plays out over months and even decades, driven by shifts in atmospheric pressure in the tropics and the Arctic that cause changing wind patterns across the northern hemisphere. For northern Europe and the Lofotens, the NAO means swings between weather that is wet and mild and cold and dry. The researchers are hoping to understand how farmers and fishers adjusted when they were faced with an oscillating climate that made farming and herding difficult, in some cases for years at a time.
Some experts think that during periods of climate-induced difficulty, Vikings responded by conducting more raids. But proving that connection will be difficult, says D’Andrea, and likely out of the scope of their research. The historical records of Viking raids aren’t detailed enough to properly compare them with climate data, he says.
But he does hope that the project will provide insights into how people throughout history adapted to climate change—insights that could potentially inform modern thinking about climate adaptation.
“When you look at a society over a 1,000-year period, you realize that changes are actually something that happen,” says D’Andrea. “We can deal with them in thoughtful, proactive ways, or we can ignore them.” Hopefully the answer to our problems won’t be to go raiding.