COLD NORSE
Did climate change force Vikings to abandon their settlements in Greenland? Glaciers offer clues,
It has often been cited as one of the classic examples of how changes in climate have shaped human history.
Circa 985, Erik the Red led 25 ships from Iceland to Greenland, launching a Norse settlement there and giving the vast ice continent its name. Within just a few decades, the Norse — also dubbed Vikings — would make it to Newfoundland as well.
The Norse maintained settlements of up to a few thousand people in southwest Greenland for several centuries, keeping livestock and hunting seals, building churches whose ruins still stand, and sending back valuable walrus tusks and other prizes for trade — until, that is, these settlements were abandoned by the mid-1400s.
Climate change has often been cited as a key element in this story, the basic notion being that the Vikings colonized Greenland in an era dubbed the “Medieval Warm Period,” which ran roughly from 950 to 1250, but then were forced to abandon their Greenland settlements as temperatures became harsher in the “Little Ice Age,” lasting from about 1300 to 1850.
Yet in a new study published this month in Science Advances, researchers raise doubts about whether the so-called Medieval Warm Period was really so warm in southern Greenland or nearby Baffin Island — suggesting that the tale of the Vikings colonizing but then abandoning Greenland due to climatic changes may be too simplistic.
Their evidence? New geological data on the extent of glaciers in the region at the time, showing that during the era when the Norse occupied the area, glaciers were almost as far advanced as they were during the subsequent Little Ice Age.
“This study suggests that while the Vikings may have left Iceland when it was relatively warm, they arrived in the Baffin Bay region and it was relatively cool,” said Nicolas Young, a professor at the Lamont-Doherty Earth Observatory at Columbia University and lead author of the study, which was conducted with three colleagues from Columbia and the University at Buffalo.
“And so it’s sort of a stretch to say that a cool climate is what drove them out of the region, when they demonstrated that they could be somewhat successful during a cool climate.”
The scientists were able to infer this from large piles of rock and mud.
When glaciers advance, they plow up earth and rock and, at their terminus, leave a large debris pile called a moraine. When glaciers then retreat, the moraine is left behind and provides evidence not only of prior glacier extent but also, if rocks and sediment can be dated, around when the glacier was at that location.
There’s a problem, though, with studying moraines to try to make inferences about glaciers during the time when the Norse occupied Greenland. The trick is that glaciers advanced after that period, during the Little Ice Age. And when they advanced, they would also have “bulldozed” prior moraines, according to Young.
However, Young and his team were able to identify key spots in western Greenland and on Baffin Island where residues from earlier moraines still existed. “We found a few locations where there are slivers of older, pre-Little Ice Age moraines, that are preserved literally just beyond the Little Ice Age moraine,” said Young.
Dating techniques were then used to confirm the age of the rocks that made up the moraines.
The researchers concluded that during the time of the Norse settlements, at least in this region around Baffin Bay and the Labrador Sea, the climate was fairly cool. The so-called Medieval Warm Period, they found, was, at best, rather inconsistent and regionally varied. That’s a conclusion other studies have also supported — with some researchers now calling it the “Medieval Climate Anomaly” to avoid any confusion, much less the incorrect idea that it was a uniform warm period such as the one in which we currently live.
“There’s certainly strong evidence in Europe that that was a real thing,” said Young of the Medieval Warm Period. “But it’s certainly not a global event; it was patchy, with quite a bit of variability.”