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Greenland icy, not green, when colonized?

A new study questions the popular notion that 10th-century Vikings were able to colonize Greenland because of unusually warm weather.

Vikings  colonized Greenland and possibly neighboring Baffin Island during what has been assumed to be—perhaps mistakenly--a temporary warm period. They disappeared in the 1400s. Southern Greenland’s Hvalsey church is the best preserved Viking ruin. Image credit: Wikimedia Commons

Vikings colonized Greenland and possibly neighboring Baffin Island during what has been assumed to be—perhaps mistakenly–a temporary warm period. They disappeared in the 1400s. Southern Greenland’s Hvalsey church is the best preserved Viking ruin. Image credit: Wikimedia Commons

A new study says the climate of Greenland was already cold when Viking settlers arrived in the 10th century. The research, based upon signs left by old glaciers, challenges the popular notion that Vikings were able to colonize Greenland because of a period of unusually warm weather. The study, published in the journal Science Advances on December 4, 2015, also suggests that climate thus probably played little role in the colonists’ mysterious disappearance about 400 years later.

On a larger scale, the study adds to building evidence that the so-called Medieval Warm Period – generally dated from about the year 950 to 1250, when Europe enjoyed exceptionally clement weather – did not necessarily extend to other parts of the world.

Climate scientists have cited the Medieval Warm Period to explain anomalies in rainfall and temperature in far-flung regions, from the U.S. Southwest to China. This new study calls those claims into question.

Glaciers usually advance during cold times and recede during warm ones. These two in western Greenland are now retreating from where they may have been when the Vikings arrived. Image credit: Jason Briner

Glaciers usually advance during cold times and recede during warm ones. These two in western Greenland are now retreating from where they may have been when the Vikings arrived. Image credit: Jason Briner

Vikings, led by Erik the Red, first sailed from recently settled Iceland to southwestern Greenland around 985, according to Icelandic records. Some 3,000 to 5,000 settlers eventually lived in Greenland, harvesting walrus ivory and raising livestock. But the colonies disappeared between about 1360 and 1460, leaving only ruins, and a longstanding mystery as to what happened. The native Inuit remained, but Europeans did not re-inhabit Greenland until the 1700s.

The Vikings’ occupation of Greenland did coincide with the Medieval Warm Period. Their disappearance did follow the onset of the Little Ice Age, which ran from about 1300-1850. Both periods are firmly documented in European and Icelandic historical records. Thus, popular authors and some scientists have fixed on the idea that nice weather drew the settlers to Greenland, and bad weather froze and starved them.

But there are no early historical climate records from Greenland showing this is in fact the case. Recently, historians have proposed more complex factors – in addition to, or instead of, climate – that drove early settlers from Greenland. Those include hostilities with the Inuit, a decline in ivory trade, soil erosion caused by the Vikings’ imported cattle, or a migration back to Europe to farms depopulated by the Black Plague.

n western Greenland, small outlet glaciers are wasting backward, leaving behind piles of rocks, or moraines, that mark their previous advances. Meltwater has formed a lake.  Image credit: Jason Briner

n western Greenland, small outlet glaciers are wasting backward, leaving behind piles of rocks, or moraines, that mark their previous advances. Meltwater has formed a lake. Image credit: Jason Briner

In the new study, the scientists sampled boulders left by advancing glaciers over the last 1,000-some years in southwest Greenland, and on neighboring Baffin Island.

Although glacial advances during the Little Ice Age wiped out most evidence of where the glaciers were during the Norse settlement, the researchers found traces of a few moraines — heaps of debris left at glaciers’ ends—that, by their layout, they could tell predated the Little Ice Age advances. An analysis of chemical isotopes in the rocks suggests that these moraines were deposited during the Viking occupation, and that the glaciers had neared or reached their later maximum Little Ice Age positions between 975 and 1275.

The strong implication: it was at least as cold when the Vikings arrived as when they left.

The findings fit with other recently developed evidence that the effects of the Medieval Warm Period were not uniform; some places, including parts of central Eurasia and northwestern North America, may actually have cooled off at that time.

Astrid Ogilvie is a climate historian currently based at Iceland’s Akureyri University. She said that as for the fate of the Viking settlers, the climate story has been dimming for some time, adding:

I do not like the simplistic argument that the Greenland people went there when it was warm, and then ‘it got cold and they died.’ I think the Medieval Warm Period has been built on many false premises, but it still clings to the popular imagination.

Read more from Columbia University

Bottom line: A new study published December 4, 2015, suggests that the climate of Greenland was already cold when Viking settlers arrived in the 10th century. The research is based upon signs left by old glaciers. It challenges the popular notion that Vikings were able to colonize Greenland because of a period of unusually warm weather.

Eleanor Imster

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