Climate played big role in Vikings' disappearance from Greenland

May 30, 2011
William D'Andrea, right, and Yongsong Huang of Brown University took cores from two lakes in Greenland to reconstruct 5,600 years of climate history near the Norse Western Settlement. Credit: William D'Andrea, Brown University

The end of the Norse settlements on Greenland likely will remain shrouded in mystery. While there is scant written evidence of the colony's demise in the 14th and early 15th centuries, archaeological remains can fill some of the blanks, but not all.

What scientists have been able to ascertain is that an extended , called the , gripped Greenland beginning in the 1400s. This has been cited as a major cause of the Norse's disappearance. Now researchers led by Brown University show the climate turned colder in an earlier span of several decades, setting in motion the end of the Greenland Norse. Their findings appear in .

The Brown scientists' finding comes from the first reconstruction of 5,600 years of from two lakes in Kangerlussuaq, near the Norse "Western Settlement." Unlike ice cores taken from the hundreds of miles inland, the new lake core measurements reflect where the lived, as well as those experienced by the Saqqaq and the Dorset, Stone Age cultures that preceded them.

"This is the first quantitative from the area they were living in," said William D'Andrea, the paper's first author, who earned his doctorate in geological sciences at Brown and is now a postdoctoral researcher at the University of Massachusetts–Amherst. "So we can say there is a definite cooling trend in the region right before the Norse disappear."

"The record shows how quickly temperature changed in the region and by how much," said co-author Yongsong Huang, professor of at Brown, principal investigator of the NSF-funded project, and D'Andrea's Ph.D. adviser. "It is interesting to consider how rapid climate change may have impacted past societies, particularly in light of the rapid changes taking place today."

D'Andrea points out that climate is not the only factor in the demise of the Norse Western Settlement. The Vikings' sedentary lifestyle, reliance on agriculture and livestock for food, dependence on trade with Scandinavia and combative relations with the neighboring Inuit, are believed to be contributing factors.

Still, it appears that climate played a significant role. The Vikings arrived in Greenland in the 980s, establishing a string of small communities along Greenland's west coast. (Another grouping of communities, called the "Eastern Settlement" also was located on the west coast but farther south on the island.) The arrival coincided with a time of relatively mild weather, similar to that in Greenland today. However, beginning around 1100, the climate began an 80-year period in which temperatures dropped 4 degrees Celsius (7 degrees Fahrenheit), the Brown scientists concluded from the lake readings. While that may not be considered precipitous, especially in the summer, the change could have ushered in a number of hazards, including shorter crop-growing seasons, less available food for livestock and more sea ice that may have blocked trade.

"You have an interval when the summers are long and balmy and you build up the size of your farm, and then suddenly year after year, you go into this cooling trend, and the summers are getting shorter and colder and you can't make as much hay. You can imagine how that particular lifestyle may not be able to make it," D'Andrea said.

Archaeological and written records show the Western Settlement persisted until sometime around the mid-1300s. The Eastern Settlement is believed to have vanished in the first two decades of the 1400s.

The researchers also examined how climate affected the Saqqaq and Dorset peoples. The Saqqaq arrived in Greenland around 2500 B.C. While there were warm and cold swings in temperature for centuries after their arrival, the climate took a turn for the bitter beginning roughly 850 B.C., the scientists found. "There is a major climate shift at this time," D'Andrea said. "It seems that it's not as much the speed of the cooling as the amplitude of the cooling. It gets much colder."

The Saqqaq exit coincides with the arrival of the Dorset people, who were more accustomed to hunting from the sea ice that would have accumulated with the colder climate at the time. Yet by around 50 B.C., the Dorset culture was waning in western Greenland, despite its affinity for cold weather. "It is possible that it got so cold they left, but there has to be more to it than that," D'Andrea said.

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Bob_Kob
3.2 / 5 (11) May 30, 2011
Wow I had no idea that our burning of fossil fuels could cause global warming in the past! We are a terrible race.
Birger
3.3 / 5 (4) May 31, 2011
NB the difference between REGIONAL cooling/warming and GLOBAL effects. At the time these changes were taking place (due to shifts in ocean currents and atmospheric jet streams) there was a strong drought in the mid-west, as winds shifted away from the damp south-eastern air from the mexican Gulf to the bone-dry air from present-day Mexico.
This drought wiped out the Anasazi indian culture and caused much mayhem among the native peoples. The warming/cooling in Greenland during this period is thus part of a continent-scale rearrarnging of climate. Other regions outside America generally went on like before.
GuruShabu
1 / 5 (5) May 31, 2011
Bob Kob, I am also very impressed with your comments! We are so bad and the damage we are causing to the environment is promoting such an extensive caos that the bloody CO2 now is travelling to the past as our "poor" atmosphere is saturated with it...
Not to mention that all the carbon imprisoned in the form of coal and oil is going to jail break and escape to the freedom of the clouds and winds...the angels will not be able to watch us any more and we will be forsaken for ever while the devil will stick his fork in our bums through the eternity!
OMG!!! We are bad!...:)
Dug
1 / 5 (1) May 31, 2011
While I am certain that burning our fossil fuel in such dramatic BTU quantities impacts our climate and our CO2 levels, I just can't jump on climate change panic band wagon. For one thing there have been far greater climate impacts than humans - (as described above) and over time and the climate has shifted back and forth covering over even those greater impacts. The Earth is about 2/3 water surface and that is one hell of a heating and cooling engine. To date it has mediated climate and far greater affects than humans.There's nothing to say that Yellow Stone's eruption and the following nuclear winter won't easily blot out the affects of man - and probably most of man kind - say next week.

I worry about the things we have direct control over - rapidly diminishing non-renewable resources, the over-population that we simply have no way to feed as peak petro-chemical and phosphate fertilizers run out over the next 30-300 years - depending on which expert you read. That's probable.

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