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Viking history is rotting from climate change

Viking history is rotting from climate change

Climate change is already rotting archaeological sites in the Arctic, and the Viking history, with its era settlements, are at high risk.

One of the archaeological sites included in the study is located in Kangeq, in the archipelago, outside Nuuk, in western Greenland. Credit: Jørgen Hollesen National Museum of Denmark.

Along the Greenland fjords are the remains of Norse outposts from the Viking age that flourished for less than 500 years before they were mysteriously abandoned. And now this lost culture is experiencing a second demise, brought on by climate change.

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

What can be lost is a unique record of remarkably preserved material: hair, tissues, human and animal bones, woods, skins, hides. As the soil warms up and the number of frost-free days increases, microbes attack these brittle organic compounds, leaving only rot.

The changes are already happening near the city of Nuuk, the capital of Greenland, says the study's lead author, Jørgen Hollesen, a senior researcher at the National Museum of Denmark. "Here we have some sites where we know that they found many artifacts, many bones, 40 years ago, but today we don't have much left," he says. "There were bones at one time, but now it's just this fine-grained porridge."

"It's clearly a big problem, pan-arctic," says Anne Jensen, an archaeologist at the University of Alaska Fairbanks, who excavated sites on the northern slopes of Alaska. Jensen worked with Hollesen on a review article 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 which sites to rush and excavate, and which to let die.

Students and scientists investigate materials found at the Norwegian site Iffiartarfik (left). One of the finds was this hand-carved bone point (right). Credit: Roberto Fortuna National Museum of Denmark.

Archaeological loss

As the Arctic warms, archaeological sites face multiple threats. Coastal erosion and rising sea levels can flood the ruins. The thickening of the vegetation can hide surface traces of archaeological sites, and the roots can penetrate and remove the archaeological layers. Finally, microbes in warmer soils can become more active, devouring organic material that has been preserved for a long time.

The new research focuses on that ultimate risk. Hollesen and his colleagues set up automated weather stations at five archaeological sites in the Nuuk region, collecting data over two years. They also took dozens of organic soil and soil samples from seven sites that stretched along a line of 120 kilometers (75 miles) from the sea eastward to the inner ice sheet. These sites were not limited to the Norse settlements, which existed between approximately 985 and 1345 A.D. They also included sites from the Saqqaq culture (2500 BC to 800 BC), the Dorset culture (300 BC to 600 AD), and the Thule culture (1300 AD to modern times).

The researchers subjected these samples to a variety of tests, from porosity to ability to conduct heat. They also tested how quickly organic material in soils decays under different humidity and temperature conditions. They then fed that information into a computer model typically used to predict changes in the soil caused by melting permafrost.

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

Priorization

That loss will be a major blow to Viking research, says Douglas Bolender, an archaeologist at the University of Massachusetts in Boston who studies Viking-era colonization of the North Atlantic and was not involved in the new research. Bolender explains that Greenland is unique in the Viking world for preserving hair, textiles, animal bones, and other fragile materials. 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 types of materials, and especially organic ones, we actually erase the experience of certain types of people," adds Bolender. State-of-the-art techniques like ancient DNA analysis can also reveal a great deal of information about how people moved and intermingled. Now it's a race against time to bring those tools to Greenland's organic produce, he says.

However, Hollesen notes that it would be impossible to excavate the more than 180,000 known archaeological sites in Greenland before the damage occurs. Russian, Canadian and Alaskan sites are suffering similar losses, he says, and even if archaeologists could save it all, there wouldn't be enough space in the world's museums to preserve it.

Hollesen and his team are now working to combine their new soil information with data on coastal erosion and damage to vegetation to produce a comprehensive risk assessment for Greenland, so that archaeologists can begin to prioritize. But among Arctic archaeologists, there is already a feeling of mourning.

"This is the cultural heritage of the people," says Jensen, "and they are losing it."

Video: How Climate Made History Pt. 2. Full Documentary (October 2020).