Climate change reveals ancient artefacts in Norway's glaciers
A
A. High above the treeline, in the loftiest parts of the Norwegian mountains, the ancient ice sheets are dwindling as the planet grows warmer. What that retreating ice surrenders as it melts are objects it has kept in frozen storage for as much as five thousand years — the arrows, skis and other gear once carried by hunters and by Viking-Age* merchants. For archaeologists, each of these finds has opened an unexpected window onto the ways in which the early inhabitants of Norway earned their living.
B
B. Cloth, hide and other organic remains are seldom recovered from archaeological sites, and the reason is simple: with little to shield them from the bacteria that drive decay, such materials rarely endure for long. Severe cold is one dependable exception, capable of holding an object more or less intact across several thousand years — though the moment it thaws, decay sets in quickly.
C
C. That is why the shrinking of the world's ice has turned glacial archaeology into a race. A delicate item, once it dries out and the wind gets at it, can disappear from the scientific record almost at once; an arrow, by contrast, may surface briefly and then be buried and protected again by the following winter's snow. Because there is no telling which will happen, those working on the ice have to approach each season methodically.
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D. For eleven years, a team led by Ingrid Solberg of the Sørdalen County Heritage Office and Marcus Halvorsen of the Nordic Institute for Glacial Archaeology surveyed the ice of Sørdalen, a highland district in central Norway ringed by some of the nation's tallest peaks. Trade routes had long wound through its passes, carrying the traders who connected Norwegian settlements with the rest of Europe; and each summer, herds of reindeer would climb onto the ice to escape the biting flies that swarmed the valleys below, with hunters following close behind them from late in the Stone Age** onwards. Because a moving glacier grinds away whatever lies beneath it, the team concentrated on ice that stays put, most of it above 1,500 metres, set among frost-shattered boulders and bare rock that spend nine months of every year under snow. 'The work is punishing — long hikes under the weight of all your kit, nights camped on permafrost — and yet there is nothing like it,' Halvorsen says. 'You are saving the archaeology, drawing attention to the melting ice, piecing together an environmental story found nowhere else, and all the while in the closest possible contact with the natural world.'
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E. Along the retreating margins of the ice, the archaeologists gathered upwards of 2,500 objects, together spanning an enormous stretch of time — from about 3,500 BCE right up to the dawn of the Renaissance in the fifteenth century. A great many of them have to do with hunting. An arrow was an easy thing to mislay, and a bow, once broken, was more often abandoned on the spot than carried the long way home. Other finds are things any traveller crossing the high passes might have used: everyday tools, skis, and pieces of horse tack.
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F. Halvorsen's team obtained radiocarbon dates for 178 of the objects and lined those dates up against the region's major turning points — spells of warming and cooling on the one hand, and on the other the social and economic changes of the era, such as the spread of farming and the widening of international trade in the run-up to the Viking Age. Certain stretches of time had left behind a wealth of objects, a sign that people had been busy in the mountains then; from other stretches there was little or nothing. The distribution of these periods was, to Halvorsen, the real surprise. Sørdalen's heights are forbidding, and in the coldest spells glaciers could seal off the upper passes and make travel there all but impossible, so one might expect people to have kept to lower ground during an episode like the sixth-century cold snap of roughly 540 to 600 CE. Instead, judging by how much they had left behind on the ice, hunters went on climbing into the mountains as often as ever. 'What is striking is that the finds seem to carry on right through that cold phase,' he says, 'which may mean that hunting in the mountains mattered more, not less, when harvests were failing in the cold.' A downturn in the Scandinavian climate would have ruined crops across the region, and the loss would have pushed more people to rely on what they could hunt.
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G. A large share of the objects belong to the early Viking Age, the eighth to the tenth centuries CE, just as the trade networks binding Scandinavia to Europe and the Middle East were growing. Scandinavian expansion tends to bring ships to mind, yet these finds are a reminder that a great deal also moved overland, along corridors like the Sørdalen passes. The expanding towns of Norway, and the markets abroad, would have generated brisk demand — for hides to keep out the cold, and for antlers from which to fashion useful objects such as combs. For a hunter, in other words, the times were good.
H
H. Norway's mountains almost certainly hold a great deal more history — and prehistory — in their remote pockets of ice. Looking again at the dates for their 178 objects, the researchers noticed an almost complete blank between roughly 3,600 and 2,000 BCE; and indeed, finds from those centuries are scarce right across Norway. It may be, they suggest, that the objects have long since crumbled away, or else that they are lying still frozen and out of reach. If so, the retreating ice of the years ahead could yet give them up.
I
I. * Viking Age: a period of European history from around 700 CE to around 1050 CE when Scandinavian Vikings migrated throughout Europe by means of trade and warfare ** The Stone Age: a period in early history that began about 3.4 million years ago
