Lining the fjords of Greenland are remnants of Viking-era Norse outposts that flourished for less than 500 years before they were mysteriously abandoned. And now this lost culture is experiencing a second disappearance, triggered by climate change.

Of all the archaeological sites in Greenland, Norse settlements are at the most risk of rotting away as the Arctic warms, according to new research published Thursday in Scientific Reports. The study estimates that up to 70 percent of the organic material in these sites could decay by 2100.

What stands to be lost is a unique record of remarkably preserved material: hair, textiles, human and animal bones, woods, hides, leathers. As the soil warms up and the number of frost-free days increases, microbes attack these fragile organics, leaving only rot behind. The changes are already happening near Greenland’s capital city of Nuuk, says lead study author Jørgen Hollesen, a senior researcher at the National Museum of Denmark. “Here we have some sites where we know that they found a lot of artifacts, a lot of bones, 40 years ago—but today we don’t see that much left,” he says. “There were bones at some point, but now it’s just this fine-grained mush.”

“It’s clearly a huge issue, pan-Arctic,” says Anne Jensen, an archaeologist at the University of Alaska Fairbanks who excavates sites on Alaska’s North Slope. Jensen worked with Hollesen on a review paper published last year in Antiquity about the impending damage, but was not involved in the current study. She says the new research and similar work could help archaeologists make grim decisions about what sites to rush and excavate, and which to let die.

ARCHAEOLOGICAL LOSS

As the Arctic warms, archaeological sites face multiple threats. Coastal erosion and sea level rise can swamp ruins. Thickening vegetation can hide surface traces of archaeological sites, and roots can penetrate into and scramble archaeological layers. Finally, microbes in warmer soil can become more active, devouring organic material that had long stayed preserved.

The new research focuses on that final risk. Hollesen and his colleagues set automated weather stations at five archaeological sites in the Nuuk region, gathering data for two years. They also took dozens of soil and soil organics samples from seven sites stretching across a 120-kilometer (75-mile) line from the sea eastward toward the Inland Ice Sheet. These sites were not limited to Norse settlements, which existed between about A.D. 985 and A.D. 1350; they also included sites from the Saqqaq culture (2500 B.C. to 800 B.C.), the Dorset culture (300 B.C. to A.D. 600) and the Thule culture (A.D. 1300 to modern times).

The researchers subjected these samples to a variety of analyses, from porosity to ability to conduct heat. They also tested how quickly the organic material in the soils decayed under different moisture and temperature conditions. Then they fed that information into a computer model normally used to predict changes in soil brought on by melting permafrost.

The results showed that if temperatures rise 2.5 degrees Celsius or 5 degrees C, these sites stood to lose between 30 percent and 70 percent of their organic materials. The Norse Viking-era sites were at the top end of the scale because they are located inland, where soils are dry, Hollesen says. Drier soil gives microbes access to more oxygen, making them more active. The researchers estimate that 35 percent of the organic materials at Viking sites could be gone in a mere 30 years.

GRIM PRIORITIZATION

That loss will be a blow to research on Vikings, says Douglas Bolender, an archaeologist at the University of Massachusetts Boston who studies Viking-age colonization of the North Atlantic and was not involved in the new research. Greenland is unique in the Viking world for preserving hair, textiles, animal bones and other fragile material, Bolender explains. Some of these materials open windows on aspects of society that would otherwise be invisible, he says. Textiles, for example, are one of the few enduring artifacts of women’s work.

“When we lose certain kinds of materials, and especially the organics, we actually erase the experience of certain kinds of people,” Bolender adds. Cutting-edge techniques such as ancient DNA analysis can also reveal a huge amount of information about how people moved and intermixed. It is now a race against time to bring those tools to Greenland’s organics, he says.

It would be impossible, however, to excavate the 180,000-plus known archaeological sites in Greenland before the damage is done, Hollesen notes. Russian, Canadian and Alaskan sites are all undergoing similar losses, he says—and even if archaeologists could save everything, there would not be enough museum space in the world to preserve it.