Viking settlers abandoned Greenland some 600 years ago. But the frozen ground has preserved centuries of the seafarers’ hardy existence on the western shores of the remote landmass, including bones and DNA. 

The Vikings, though, didn’t first step foot on Greenland. The Saqqaq people arrived there first, around 3,800 years before the Vikings, as did other nomadic peoples. Yet now, all of their culturally invaluable organic remains are under threat from amplified Arctic warming — the fastest changing region on Earth. 

Archaeologists, geochemists, and climate scientists traveled to Greenland and collected soil samples from seven archaeological areas to determine how vulnerable the sites are to warming. Their research, published Thursday in the journal Scientific Reports, found these organic archaeological remains (also known as organic carbon) will accelerate their decay as they become exposed to increasingly warmer climes and hungry microorganisms.

“If temperatures go up, degradation rates will increase,” said Jørgen Hollesen, lead author of the research and a senior researcher at the National Museum of Denmark.

Global temperatures are certainly expected to go up. Eighteen of the 19 warmest years on record have occurred since 2001, and Greenland specifically is now melting at rates Arctic scientists have called “off the charts.” What’s more, dwindling Arctic sea ice this year is on pace to either break or nearly break its record for lowest extent. 

On the shores of Greenland inhabited by the Vikings,  warmer summers allow the ground to thaw and exposes the soil to oxygen, allowing microbes to thrive and consume previously preserved remains. “The higher the temperature, the higher the rate of consumption,” Hollesen said succinctly.

“They’ll decay very rapidly,” agreed Christopher Rodning, an archaeologist at Tulane University who had no involvement in the research.  

There are some 6,000 archaeological sites around Greenland, and they are invaluable relics of the Viking past, and of peoples before and after them. “The archaeological sites have a lot to teach us about those [historical] episodes,” said Rodning. Especially if these sites have preserved organic remains, like food stored in a freezer.

“As an archaeologist I can say it’s really exciting when we do find an object made out of wood, or animal bone,” Rodning said. These materials can reveal the contents of ancient diets, the diseases people carried, and rare genetic material. “They have huge potential to help understand the lives of these people,” he said.

Hollesen and his team are keenly aware of this reality, so they’re now working to gauge which sites around Greenland are most vulnerable to warming, in order that the remains be preserved or excavated before they’re gone. It’s like archaeological triage.

If temperatures keep trending as they are today, a scenario climate scientists call “business as usual,” up to 70 percent of the organic carbon inside the coastal remains could decay over the next 80 years (by 2100). Even if humanity begins ambitiously slashing its carbon emissions by mid-century, some 30 percent of these organic remains could degrade by then, according to the research. 

And farther inland, where many Viking settlers were buried, over 35 percent of organic material could be lost by 2050. 

After collecting soil from different Greenland sites, Hollesen and his team exposed the soil to different temperatures in a laboratory, and measured the oxygen consumption by microbes, because the microbes need oxygen to survive. Then, his team projected how much degradation these microbes would achieve at different climate scenarios — climate scenarios that are based specifically on how much heat-trapping carbon humans emit into the atmosphere this century.

Centuries ago, the Vikings came and went from Greenland, while other peoples, the Inuit, didn’t leave. Answers about why some cultures continued to adapt to the harsh Arctic, while others left, are likely stored in the warming, decaying, Greenland soil.

“As archaeologists, these are questions we still need to be asking,” said Rodning.