How Scientists Dated the Vikings’ Arrival in America

Vikings reached North America roughly five centuries before Columbus, but for decades, archaeologists could only say it happened somewhere around the year 1000. A burst of cosmic radiation finally let them pin down the exact year.

A Site Discovered in 1960, A Date That Took Decades

Norwegian archaeologists discovered L’Anse aux Meadows, the remains of a Norse settlement, in Newfoundland, Canada, in 1960. The site, now a UNESCO World Heritage Site, contains the remnants of timber-and-sod buildings along with iron nails and bronze pins consistent with the two medieval Icelandic sagas describing Viking voyages to a place called Vinland: the Saga of the Greenlanders and the Saga of Erik the Red, both centered on Leif Erikson. For decades after the site’s discovery, around 1000 CE was the most precise date archaeologists could offer.

A Solar Storm as a Timestamp

That changed with a discovery about the sun rather than about the Vikings themselves. In 2012, physicist Fusa Miyake identified a global spike in atmospheric carbon-14 preserved in tree rings, later understood to result from an intense burst of cosmic ray particles striking Earth’s upper atmosphere. Events like this are now called Miyake events. One such burst occurred in 993 CE, and because trees worldwide absorbed that radiocarbon into the growth ring corresponding to that year, the resulting chemical signature shows up in ancient wood everywhere from Newfoundland to New Zealand, functioning as a global, single-year timestamp.

Three Trees, One Precise Year

Researchers led by Margot Kuitems applied this method to three conifer wood samples from L’Anse aux Meadows that still had visible rings and an intact outer growth edge. The cut marks on the wood came from metal axes, tools known to the Vikings but not to the Indigenous peoples already living in the region at the time. By locating the 993 CE carbon-14 spike within each sample and counting outward ring by ring to the bark, the team dated all three trees to exactly 1021 CE. The findings, published in Nature in 2021, gave archaeologists the earliest precisely dated evidence of a European presence anywhere in the Americas, some 471 years before Columbus’s 1492 voyage. The study’s authors described the date as marking the first known point at which humans had encircled the globe.

A New Study Urges Caution

The story doesn’t necessarily end there. A 2026 review in the journal New Phytologist, led by Amy E. Hessl of West Virginia University, cautions that individual trees may not record atmospheric carbon-14 identically. While Miyake event signals generally show up with remarkable synchrony across samples, the authors found enough variability between individual trees to complicate using tree rings as a fully precise indicator of exactly when, and how strongly, past radiocarbon spikes occurred. That doesn’t undo the broader finding that Vikings were active in Newfoundland right around the turn of the millennium, but it does mean the specific year 1021 may carry more uncertainty than researchers previously assumed, keeping the debate over precise Viking chronology very much alive.

Sources

This report draws on original reporting by Popular Mechanics, republished by Old Norse, and the peer-reviewed studies published in Nature (2021) and New Phytologist (2026).