Norsemen may have arrived in Iceland as much as 70 years earlier than previously believed, and their arrival might not have been the environmental catastrophe often depicted.

Traditionally, it’s stated that Iceland saw its first settlement in the 870s. This early migration is frequently viewed as an ecological calamity brought on by Viking raiders and Norse settlers who cleared the forests for fuel, construction materials, and arable land. Today, less than 2 percent of the country is still forested.

Finding concrete evidence regarding the arrival of these early settlers has been challenging. Archaeologists have discovered an ancient wooden longhouse, estimated to be from around 874 AD, located near Stódvarfjordur in eastern Iceland. This old longhouse is thought to have been a summer dwelling established in the 800s, though this finding has yet to be documented in scientific journals.

Currently, Eske Willerslev, a professor at the University of Copenhagen, and his team examined environmental DNA (eDNA) gathered from sediment cores drilled in Lake Tjörnin, an area in central Reykjavík, one of Iceland’s earliest and continuously inhabited locations, to identify which species existed and their timestamps. They analyzed volcanic ash layers, alongside radiocarbon dating and plutonium isotope assessments, to develop a timeline from about 200 AD up to contemporary times, integrating known historical events.

A significant marker in their research is the Randonham tephra layer, formed from volcanic ash deposited during eruptions around 877 AD. The bulk of evidence indicating human habitation in Iceland is found above this layer, indicating subsequent settlement.

“The signs beneath the tephra provide compelling evidence for earlier human activity,” Comments Chris Callow from the University of Birmingham, UK, who did not participate in the research.

Willerslev and his colleagues postulate that humans may have arrived as early as 810 AD. This inference is based on an observed rise in levoglucosan, a compound linked to biomass burning, and a subsequent increase in sewage-related viruses.

“If it were 850, I wouldn’t have been so surprised, but 810 represents rapid Viking expansion in the North Atlantic,” Callow remarks. “Overall, this aligns with our suspicions, but a date as early as 810 remains contentious.”

While piecing together a thorough environmental history of the region is noteworthy, the evidence supporting such an early arrival remains questionable. Kathryn Catlin from Jacksonville State University in Alabama stated, “The sewage biomarkers only show a slight increase around 800, nothing until 1900. Where are the indicators of sewage and human activity in between?” She also pointed out that while biomass burning could imply human presence, natural occurrences like lightning could also ignite fires.

Willerslev and his colleagues opted not to conduct interviews. New Scientist also noted that the settlers’ arrival corresponded with an uptick in local biodiversity. Genetic data imply they brought grazing animals, cultivated hay, and grew barley on a small scale for brewing purposes.

In contrast to the widespread narrative of swift deforestation, eDNA from pollen samples revealed that birch and willow trees expanded during the settlement era. Notably, birch pollen grains rose fivefold between 900 and 1200 AD, a shift researchers believe may have been influenced by settlers managing the area to protect timber and fuel sources.

“This significantly contradicts earlier claims that Vikings arrived in Iceland and immediately caused environmental destruction,” Katrin stated.

Although sheep, cattle, pigs, and horses do not appear in considerable numbers until decades after the initial settlement, Willerslev and his colleagues propose this lag may stem from the 20-year period required to build up detectable herds in eDNA records.

Callow posits another explanation: the first inhabitants may have only visited during the summer months for walrus ivory, possibly arriving without many animals. “They could have intended to hunt a few walruses and return home,” he suggested.

eDNA indicators imply the significant loss of biodiversity, including birch and willow trees, didn’t transpire until after 1200. Willerslev and his team associate this decline with the cooler climate associated with the Little Ice Age, rather than direct effects from settlers. This marked a period of colder temperatures from approximately 1250 to around 1860, compounded by volcanic eruptions and storm surges.