A thousand years ago, powerful Viking chieftans flourished in Norway’s Lofoten Islands, above the Arctic Circle. In an environment frequently hovering on the edge of survivability, small shifts in climate or sea level could mean life or death. People had to constantly adapt, making their living from the land and the sea as best they could. By plumbing the bottoms of deep lakes near key archaeological sites, scientists from Columbia University’s Lamont-Doherty Earth Observatory and other institutions are trying to understand how the Vikings did it. READ THE FULL SCIENTIFIC STORY
In the chilly 24-hour daylight of a spring night, Lamont-Doherty climatologist William D’Andrea surveys Borgpollen, an inland bay on the island of Vestvagoya. Connected to the Atlantic Ocean by a series of passages, the bay once was home to Vikings and their seagoing ships. Some of the islands’ best crop and grazing land is in surrounding hills and valleys, but it was often marginal, depending on weather.
In the 1980s, a farmer plowing his field hit upon the remains of the biggest Viking dwelling ever found—a longhouse that measured some 270 feet end to end. This replica was constructed next to the site, and now houses the popular Lofotr Viking Museum.
Replica vessels owned by the museum lie anchored in the bay. Viking ships were used not just for the famous pillage-and-plunder expeditions, but fishing, especially for the abundant cod that still fuel the islands’ economy. A climate marginal for farming may have been a factor in the formation of the Vikings’ raiding culture.
Lamont grad student Lorelei Curtin (right) and College of William & Mary undergrad Eve Pugsley venture onto a lake where the team plans to collect mud from the bottom. Lakes, fjords and bays are natural repositories of material washed in from land, and thus comprise a potential record of natural changes and human activities going back millennia.
Out on the water, D’Andrea (right) and William & Mary student Moussa Dia assemble a mechanism that they will use to take a core of the bottom.
The team lowers the corer on a rope until it hits bottom; they will then pound it into the muck from above with a hammer attached to a second rope.
After filling the core tube, they dislodge it from the bottom, haul it back up and wrestle it into the boat.
It’s just mud, but each core potentially tells a story, layer by layer. Remains of aquatic algae can gauge temperature at different times; waxy substances from leaves, what kinds of plants were growing on land; soot, the prevalence of natural or manmade fire; compounds from fecal matter, the numbers of sheep, cattle or humans present at any one time.
This core, from a small pond near the seashore, shows a sudden, visible shift. Coarse sand on the bottom indicates that the spot was once a wave-washed beach. Then the sea receded, and the beach became an inland pond, where only fine muck built up. The land here has been rising over much of the last 10,000 years, causing the relative sea-level drop.
Sea levels had powerful effects on the Vikings and their predecessors. Tromso University Museum archaeologist Stephen Wickler (right) and pollen specialist Scott Anderson of Northern Arizona University survey a terrace once inhabited by seagoing Stone Age people. Some 6,000 years ago, this was convenient waterfront property; now, it is 30 vertical feet above the nearest beach.
Vikings once sallied out through this passage from Borgpollen to the ocean, on their way to fish, trade, raid or explore. They and their contemporaries ranged all the way to the Mediterranean and Newfoundland .
Further inland, looking seaward through the narrowest part of the Borgpollen passage. About 1,000 years ago, rising of the land finally made it too shallow for large ships to pass, and maritime activities withered. Now the passage is crossed by the E10 highway, a popular route for tourists.
Livestock had to be extra tough to survive long-term cold spells. These horses on the island of Flakstadoya are almost certainly descended from ancient local breeds; similar horses are seen in Iceland, which was colonized by Vikings.
When the weather cooperated, Vikings farmed a few cold-weather crops such as barley and kohlrabi. With a permanent shortage of arable land, farms like this one on Flakstadoya probably have been worked continuously for thousands of years.
The decline of Viking raids, around 1000 AD, could have been influenced by natural changes. But social and political factors probably played major roles; these would have included the rise of large kingdoms and Christian church hierarchies that displaced the Norse religion and reined in local chiefs.
Residents of the Lofotens have always depended on the cod fishery, which became a major export industry as the Vikings declined. Today, cod heads dry by the millions on seaside racks.
At the Borg Viking Museum, visitors can try out chain mail, helmets and weapons modeled by modern craftsmen.
Viking reenactor Kim Holte spins yarn from sheep’s wool, which she will later knit into clothing. Her family is from the northern mainland; she says she may well be descended from the ancient people who invented such crafts.
The Vikings never really left the Lofotens; their descendants people the landscape. Residents of the village of Sorvagen march in the yearly May 17 parade, marking Norway’s declaration of independence from Sweden and Denmark in 1814.
Adaptation to change remains vital here. Fleeing modern violence, recently many immigrants from the Mideast, Africa and Asia have landed in the Lofotens. They apparently are welcome; these two women marched arm in arm in the parade.
AGU25, the premier Earth and space science conference, takes place December 15-19, 2025 in New Orleans, Louisiana. This year’s theme—Where Science Connects Us—puts in focus how science depends on connection, from the lab to the field to the ballot box. Once again, Lamont-Doherty Earth Observatory and Columbia Climate School scientists, experts, students, and educators are playing an active role, sharing our research and helping shape the future of our planet. #AGU25 Learn More
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