1. The Medieval Climate Anomaly and the Vikings
From 800AD to 1100, the Vikings (people from Norway, Sweden and Denmark) travelled far – to raid, plunder, trade and settle. They went to Finland, Poland, Russia, modern Turkey, England, France, Northern Scotland, Ireland, Iceland, Greenland and N America.
They recorded their travels in Sagas.

2. The climate varies a lot in Iceland and Greenland!
Affected by:
Position of Storm Track/ Jet Stream
Oceanic Currents
North Atlantic Oscillation
Sea-Ice in Greenland sea
The climate in Iceland and Greenland can change differently to the climate in Europe

3. North Atlantic Oscillation
The common pressure features seen in the North Atlantic Ocean are for large regions of relatively high pressure centred over the Azores islands (west of Portugal, known as the sub-tropical or Azores high) and low pressure centred over Iceland (the sub-polar or Icelandic low). The NAO describes the relative changes in pressure between these two regions (Azores minus Iceland), and was discovered in the 1920s by Sir Gilbert Walker.
This has a strong influence on winter weather and climate patterns in Europe and North America.
Acting like a giant seesaw, the NAO leads to changes in the intensity and location of the North Atlantic jet stream - ribbons of very fast winds high in the atmosphere that influence the movement of regions of low pressure (depressions) and their associated storms.
Positive NAO phase
The positive NAO phase represents a stronger than usual difference in pressure between the two regions.
Winds from the west dominate, bringing with them warm air, while the position of the jet stream enables stronger and more frequent storms to travel across the Atlantic
These support mild, stormy and wet winter conditions in northern Europe and eastern US. Conversely, northern Canada, Greenland and southern Europe are prone to cold and dry winter conditions.
Negative NAO phase
The negative NAO phase represents the reverse with a weaker than usual difference in pressure.
Winds from the east and north-east are more frequent, bringing with them cold air, while the adjusted position of the jet stream leads to weaker and less frequent storms.
As a result, Europe and eastern US are more likely to experience cold, calm and dry winters. In contrast, northern Canada and Greenland will tend to be mild and wet.
“The Vikings knew that colder than normal temperatures in Greenland were associated with storminess elsewhere”

4.
Haine, Weather, 2008

5. Vikings in Iceland Colonised between 870-930AD, probably 871
No native peoples or grazing animals
Extensive vegetation and trees when the Vikings arrived: erosion soon became a problem
Greenland Ice cores show warmer temperatures between AD.
Farms prosperous in medieval times were engulfed by glaciers by 1700
Dodgy source:
Olafur Einarsson ( ), a pastor in eastern Iceland, wrote the following poem (Bryson, 1977) which illustrates the troubles Icelanders faced:
Formerly the earth produced all sorts
of fruit, plants and roots.
But now almost nothing grows....
Then the floods, the lakes and the blue waves
Brought abundant fish.
But now hardly one can be seen.
The misery increases more.
The same applies to other goods....
Frost and cold torment people
The good years are rare.
If everything should be put in a verse
Only a few take care of the miserables....
Lamb (1995) reports that the population of Iceland fell from about 77,500, as indicated by tax records in 1095, to around 72,000 in By 1703 it was down to 50,000, and after some severe years of ice and volcanic eruptions in the 1780's it was only 38,000. Average height declined from 5'8" during the tenth century to 5'6" in the eighteenth century. Lamb (1995) attributes much of the decline in population to the colder climate and increased ice flow. The harvest years were so cold that there was little hay to feed the livestock so thousands of sheep died. During the MWP, Icelanders grew grain over much of the island but by the early 1200's only barley, a short-season grain, was being grown. Lamb (1995) notes that there was also an increase in glacier growth and subsequent flooding from bursts due to volcanic activity under the ice. By the 1500's conditions were so bad that all attempts at grain growing were abandoned and Icelanders turned solely to the sea for their survival. The shellfish near the shores were destroyed by increasing amounts of ice so cod fishing became the Icelanders main source of food and trade. As the cooler waters moved southward, the cod were forced farther southward until they were too far offshore for the primitive Icelandic ships to reach.

6. Vikings in Greenland Erik the Red, Thorvaldsson
About 985AD – in the middle of a period with less sea ice
The settlers experienced above average temperatures for the first crucial years.
Eastern Settlement on the south coast, abandoned by 1500
Some Eastern settlement graves are now in permanently frozen ground.
Western settlement near current Nuuk, abandoned around 1350
Sea ice limited trade, fishing and the essential arrival of driftwood
Why were settlements abandoned??
In the Eastern settlement, the Vikings were reliant on grazing animals with a few crops. When there was sea-ice, they couldn’t access the sea to fish or trade. Driftwood was essential for Viking house and boat construction.
In the Western settlement, which experiences more sea-ice and has a harsher climate, hunting of sea and marine animals was crucial, but its not clear whether they ever learned the Inuit techniques for hunting on ice.
Many factors associated with abandonment; climate (and sea ice) must have played a part
Some mystery about what happened to the hundreds of people who were there.
Popular authors and some scientists have fixed on the idea that nice weather (MCA) drew the settlers to Greenland, and bad weather (Little Ice Age) froze and starved them.
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/ assimilation with the Inuit, genetic degradation, a decline in ivory trade as African ivory became available, soil erosion caused by the Vikings’ imported cattle, or a migration back to Europe to farms depopulated by the Black Death.
Hvalsey Church, Eastern Settlement

7. Vikings in North America
Leif Eriksson, Erik the Red’s son, arrived in 1000AD
Vínland (wineland), Helluland (slab land), Skaeling land (wretch land) and Markland (forest land)
Travel between Greenland and North America would only have been possible for 2 months of the year
In years of heavy sea-ice, travel would have been perilous
Conflicts with indigenous people probably led to the abandonment of the settlements after a few years
At least 2 Viking settlements in North America have now been found.
“The country seemed to them so kind that no winter fodder would be needed for the livestock: There was never any frost all winter and the grass hardly withered at all”
A description of Vinland from the Greenland Saga

8. https://phys. org/news/2013-09-sea-ice-formation-sustained-ice-age

9. Hafgerdingar “sea hedges”
Probably an Arctic superior mirage
Occurs in anticyclonic conditions
Temperature inversion with temperatures rising more than 0.11°C/m with height
These make it possible to see Shetland from Norway, the Faeroes from Shetland, Iceland from the Faeroes, East Greenland from Iceland and Baffin Island from West Greenland