The Little Ice Age: How Climate Made History 1300-1850 Read online

  At least 100,000 people died along the Dutch and German coasts in four fierce storm surges in about 1200, 1212-19, 1287, and 1362, in long-forgotten disasters that rivaled the worst in modern-day Bangladesh. The Zuider Zee in the northern Netherlands formed during the fourteenth century, when storms carved a huge inland sea from prime farming land that was not reclaimed until this century. The greatest fourteenth-century storm, that of January 1362, went down in history as the Grote Mandrenke, the "Great Drowning of Men."3 A fierce southwesterly gale swept across southern England and the English Channel, then into the North Sea. Hurricane-force winds collapsed church towers at Bury St. Edmunds and Norwich in East Anglia. Busy ports at Ravenspur near Hull in Yorkshire and Dunwich on the Suffolk shore suffered severe damage in the first of a series of catastrophes that eventually destroyed them. Huge waves swept ashore in the Low Countries. A contemporary chronicler reported that sixty parishes in the Danish diocese of Slesvig were "swallowed by the salt sea." At least 25,000 people perished in this disaster, maybe many more: no one made accurate estimates. The fourteenth century's increased storminess and strong winds formed huge dunes along the present-day Dutch coastline. Amsterdam harbor, already an important trading port, experienced continual problems with silting caused by strong winds cascading sand from a nearby dune into the entrance.

  In the early 1400s, more damaging storm surges attacked densely populated shorelines. On August 19, 1413, a great southerly storm at extreme low tide buried the small town of Forvie, near Aberdeen in northeastern Scotland, under a thirty-meter sand dune. More than 100,000 people are said to have died in the great storms of 1421 and 1446.

  Judging from North Atlantic Oscillation readings for later centuries, the great storms of the fourteenth and fifteenth centuries were the result of cycles of vigorous depressions that flowed across northwestern Europe after years of more northerly passage when the NAO Index was low. The changing signals of hydrogen isotopes from a two-hundred-meter section of Greenland ice core GISP-2 tell us summer and winter temperatures for the fourteenth century. This hundred-year period saw several wellmarked cycles of much colder conditions, among them 1308 to 1318, the time of Europe's massive rains and the Great Famine; 1324 to 1329, another period of unsettled weather; and especially 1343 to 1362, when stormy conditions in the North Sea culminated in the "Great Drowning" and the Norse Western Settlement struggled through its exceptionally cold winters.

  Sometime between 1341 and 1363 (the date is uncertain), Norwegian church official Ivar Bardarson sailed northward with a party of Norse along the western Greenland coast from the Eastern to the Western Settlement, charged by local lawmen to drive away hostile skraelings who were rumored to be attacking the farms. He found the Western Settlement deserted, a large church standing empty and no traces of any colonists. "They found nobody, either Christians or heathens, only some wild cattle and sheep, and they slaughtered the wild cattle and sheep for food, as much as the ships would carry."4 While Bardarson blamed elusive Inuit, whom he never encountered, his account is puzzling, for one would assume that the marauding hunters would have killed the livestock. Bardarson seems to have visited a ghost town abandoned without apparent reason. But modern archaeological excavations reveal a settlement that was dying on its feet from the cold.

  Ever since Eirik the Red's time, the Greenlanders had lived off a medieval dairying economy just like those in their homelands. Even in good years with warm summers and a good hay crop, they lived close to the edge. Their survival depended on storing enough hay, dried sea mammal flesh, and fish to tide humans and beasts over the winter months. The Norse could usually survive one bad summer by using up the last of their surplus the following winter. But two successive poor hay crops placed both the animals and their owners at high risk, especially if lingering ice restricted summer hunting and fishing. The ice-core analyses for 1343 to 1362 reveal two decades of much colder summers than usual. Such a stretch, year after year, spelled disaster.5

  The main house block of a small manor farm called Nipaatsoq tells a grim story of the final months of its occupation. Animals and people lived in separate rooms linked by interconnecting passages. Each spring, the owners swept out the reeds and grass that covered the floors and emptied dung from the byres, yet the archaeologists found the debris of the very last winter's occupation intact. No one had been left to clean up in the spring.

  Five dairy cows once occupied the manor's byre. The hooves of these five beasts, the only part of a cow that has no food value whatsoever, were scattered among other food remains across the lower layer of one room. The owners had butchered the dead animals so completely that only the hooves remained. They did this in direct violation of ancient Norse law, which for obvious reasons prohibited the slaughter of dairy cows. In desperation, they put themselves out of the dairy business by eating their breeding stock.

  The house's main hall, with its benches and hearths, yielded numerous arctic hare feet and ptarmigan claws, animals often hunted in winter. The larder contained the semi-articulated bones of a lamb and a newborn calf, and the skull of a large hunting dog resembling an elkhound. The limb bones of the same animal lay in the passageway between the hall and sleeping chamber. All the dog bones at the manor farm came from the final occupation layer and displayed the butchery marks of carcasses cut up for human consumption. Having first eaten their cows and then as much small game as they could take, the Nipaatsoq families finally consumed their prized hunting dogs.

  The houseflies tell a similar tale. Centuries before, the Norse accidentally introduced a fly, Telomerina flavipes, which flourishes in dark, warm conditions where feces are present. Telomerina could only have survived in the warmth of the fouled floors of the main hall and sleeping quarters, where their carcasses duly abounded. Quite different, cold-tolerant carrion fly species lived in the cool larder. Once the house was abandoned, the cold-loving flies swarmed into the now empty living quarters as the fires went out. Telomerina vanishes. The uppermost layer of all, accumulated after the house was empty, contains species from outside, as if the roof had caved in.

  There were no human skeletons in the house-no remains of dead the survivors were too weak to bury, no last survivor whom no one was left to bury. With but a few seals for the larder, the Nipaatsoq farmers may have simply decided to leave. Where and how they ended up is anybody's guess. Had they adopted toggling harpoons and other traditional ice-hunting technology from their Inuit neighbors a few kilometers away, they could have taken ring seal year round and perhaps avoided the late spring crises that could envelop them even in good years. Perhaps they had an aversion to the Inuits' pagan ways, or their cultural roots and ideologies were simply too grounded in Europe to permit them to adapt.

  Another isolated Norse settlement, known to archaeologists as Gard Under Sander (Farm Beneath the Sand) lay inland, close to what was once fertile, rich meadowland just ten kilometers from Greenland's ice cap. Farm Beneath the Sand began as a long house used first as a human dwelling, then as an animal shed. In about 1200 the hall burnt down. Several sheep perished in the blaze. The farmers now built a centralized farmhouse, like that at Nipaatsoq, with constantly changing rooms, not all of them in use at one time, as the stone-and-turf farm changed over more than two centuries. Late in the 1200s, the climate deteriorated, local glaci ers advanced and the pastures sanded up. Farming became impossible and the settlement was abandoned. After abandonment, sheep that were left behind continued to shelter in the empty houses, as did overnighting Thule hunters."

  The Norse kept a foothold at the warmer Eastern Settlement for another 150 years. Here they lay close to the open North Atlantic, where changing fish distributions, southern spikes of pack ice, and new economic conditions brought new explorers instead of the traditional knarrs. Basques and Englishmen paused to fish and to trade for falcons, ivory, and other exotic goods. But above all, they pursued whales and cod.

  In the eighth century, the Catholic Church created a huge market for salted cod and herring by al
lowing the devout to consume fish on Fridays, the day of Christ's crucifixion, during the forty days of Lent and on major feast days. The ecclesiastical authorities still encouraged fasting and forbade sexual intercourse on such occasions, also the eating of red meat, on the grounds it was a hot food. Fish and whale meat were "cold" foods, as they came from the water, and were thus appropriate nourishment for holy days. But fish spoils quickly, and in the days before refrigeration, drying and salting were about the only ways to preserve it. Dried salt cod and salted herring quickly became the "cold" foods of choice, especially during Lent. Salted cod kept better than either salt herring or whale meat and was easily transported in bulk.

  Cod had been a European staple since Roman times. Dried and salted fish was light and durable, ideal hardtack for mariners and armies. In 1282, preparing to campaign in Wales, King Edward of England commissioned "one Adam of Fulsham" to buy 5,000 salted cod from Aberdeen in northeastern Scotland to feed his army. Salt cod fueled the European Age of Discovery and was known to Elizabethan mariners as the "beef of the sea." Portuguese and Spanish explorers relied heavily on it to provision their ships during their explorations of the New World and the route to the Indies around the Cape of Good Hope. No one held the stuff in high esteem. On land and at sea, people washed it down with beer, cider, malmsey wine, or "stinking water" from wooden barrels. For centuries, thousands of fishermen, especially Basques from northern Spain, Bretons, and Englishmen, pursued cod despite horrifying casualty rates at sea in all weathers. A commodity with a value higher than gold, cod sustained entire national fisheries for centuries.?

  The Atlantic cod, Gadus morhua, flourishes over an enormous area of the North Atlantic, with a modern range from the northern Barents Sea south to the Bay of Biscay, around Iceland and the southern tip of Greenland, and along the North American coast as far south as North Carolina. Streamlined and abundant, it grows to a large size, has nutritious, bland flesh, and is easily cooked. It is also easily salted and dried, an important consideration when the major markets for salt cod were far from the fishing grounds, and often in the Mediterranean. When dried, cod meat is almost 80 percent protein.

  Cod are highly temperature sensitive and poorly suited to extremely cold water. Their kidneys do not function well below about 2°C, but the fish thrive in water between 2 and 13°C. Temperatures between 4 and TC are optimal for reproduction. Greenland is a telling indicator of how cod populations move with changing water temperatures. For much of the past five cool centuries, the waters of Greenland were too cold for large cod populations except in the most sheltered areas. After 1917, the warmer Irminger current, which flows south of Iceland, extended around Greenland's southern tip. Cod eggs and larvae from spawning grounds north and west of Iceland were carried across the Denmark Strait and around the southern tip of Greenland by the West Greenland Current. By 1933, water temperatures were high enough for cod to thrive up to 72° north. By 1950, cod still abounded as far north as Disko Bay, at 70° north. During the past four decades, the water has turned much colder and Greenland cod stocks have plummeted.8

  Similar movements of water masses and the resulting changes in sea temperatures affected cod populations in past centuries. We can sometimes track the effects in fisheries records. During the bitterly cold seventeenth century, northern sea temperatures fell below the critical 2'C level along the Norwegian coast and far southward for periods of twenty to thirty years. The Faeroes cod fisheries failed totally in 1625 and 1629. There were no cod after 1675 for many years. By 1695, they were sparse even as far south as the Shetland Islands. The scarcity pertained for most of the time between about 1600 and 1830, during the coldest episodes of the Little Ice Age. Similar shifts in cod populations undoubtedly occurred in earlier centuries, especially during the cooling of the thirteenth century just when the demand for dried and salted cod was exploding. Had we the historical records, the changing distribution of cod in the far north would be a remarkable barometer of rising and falling sea temperatures. As it is, there is a strong connection between deteriorating climatic conditions, new designs of oceangoing fishing vessels, and an inexorable spread of cod fishing away from the European continental shelf onto another shelf, off virtually unknown lands far to the west.

  During medieval times, the Basques of northern Spain, who controlled abundant salt deposits, acquired a sterling reputation as whale hunters.9 They sold fresh and salted whale meat as "cold" flesh for holy days as far afield as London and Paris. By the ninth century they were skirmishing with the Norse in the Bay of Biscay and had begun to copy their adversaries' clinker-built ships, with overlapping planks fastened with iron rivets. The Norse, Europe's consummate long-distance voyagers, used dried cod as hardtack at sea as well as to sustain themselves during the winter months. Long before Eirik the Red sailed to Greenland, the Norse processed large quantities of cod and traded the surplus far and wide. The Lofoten islands in northern Norway were a major source of dried cod in the north as early as the twelfth century. The cold, dry winds and sunny conditions of early spring were ideal for desiccating split fish carcasses.

  Atlantic cod are unknown off northern Spain but were common in the northern summer whaling grounds of Norway and the North Sea that became accessible to new generations of Basque fisherfolk once they began building Norse-style boats in the twelfth century. They pursued cod from the same small open dories they used to stalk whales, and applied the same salting methods as well. Like the Norse, they lived off cod hardtack at sea, sailing as far north as Norway, the Hebrides, even Iceland. By the fourteenth century, salted and dried Basque cod, bacalao in Spanish, was known throughout Spain and the Mediterranean. The Basques prospered off cod and boatbuilding. Their large, beamy ships with their exceptional hold capacity were in demand throughout Europe.

  In the mid-fourteenth century, as ice conditions in the north became more severe and water temperatures fell, the cod stocks off Norway began to falter. Iceland had become increasingly isolated. The great days of Norse voyaging were over, and the islanders, living in a timberless land, showed little inclination to become seamen. They continued to fish for cod from small open boats close inshore-a tradition that would continue until the nineteenth century-while others reaped a rich fish harvest offshore. Year after year, no Norwegian ships arrived, nor vessels from elsewhere, except when a shipload of Scots was wrecked and "none understood their language."10 Norway's close monopoly over trade with its dependency, maintained for generations, withered in the face of competition from the ever more aggressive Hanseatic League, based on the Baltic. The League was a powerful commercial association of member cities based in Lubeck in Germany, which reached the height of its power in the fourteenth century. The Hansa was a mercantile organization with significant political clout, which levied taxes to suppress piracy and inevitably became involved in the politics of established kingdoms. Its members dominated trade over northern Europe until the fifteenth century, when aggressive modern states provided overwhelming competition. For a time, the League effectively controlled Denmark's monarchy.

  Iceland was "the desert in the ocean," increasingly isolated, her population decimated by the Black Death and increasingly severe winters. When Norway and Sweden were united with much more powerful Denmark in 1397, Iceland found itself at the mercy of a more distant, rapacious master who laid even heavier taxes on the island. The angry Icelanders were ready to ignore Norway's monopoly and welcome any foreign ships that arrived at their shores.

  For generations, English fishermen and merchants had sought cod in Norwegian waters. The trade prospered despite a requirement that all catches had to be brought into the port of Bergen for taxation before export. The tax was little more than a nuisance until a cabal of Hansa merchants who controlled Bergen effectively closed Norwegian fisheries to foreigners in 1410. The prohibition may have been prompted by falling cod stocks off Norway due to colder water conditions. For English fishing communities, the only chance for good catches now lay in an increasingly stormy North S
ea and much further afield in Iceland's cold, remote waters, where cod were known to abound. English fishing fleets would have to sail far offshore in the depths of winter to bring salt cod to market in time for the autumn sales. The ships of the day were ill equipped for such voyaging.

  The prudent medieval mariner avoided going to sea in winter. Thirteenth-century Scandinavians with their open boats stayed ashore from November to March. According to an early English poem, The Seafarer, Anglo-Saxons did not venture onto the open ocean until after the first cuckoo of early summer. They were wise, for severe gales are eight times more frequent in these waters during winter than in summer, with rough seas at least every fourth winter day, perhaps even more often during low cycles of the NAO. A higher frequency of gale-force winds and high seas between May and September, after centuries of kinder weather, would have wreaked havoc with fishing fleets and the heavy merchant vessels that plied these waters. Even into the twentieth century, decked, engineless fishing boats stayed in port if the wind blew above 30 knots (about 35 miles per hour). The undecked vessels of earlier times would not have left harbor in a strong breeze of more than 20 to 25 knots.

  Even in favorable weather, medieval seafaring under oar and sail required a more intimate knowledge of ocean and weather than is possessed by almost anyone today. Patience and experience compensated for many deficiencies in ship design. Wise seamen, knowing the perils of sudden storms and strong headwinds, might wait at anchor for weeks on end for favorable winds. Even with more efficient rigs and infinitely more seaworthy ships, the rhythms of life under sail endured into this century. During the 1930s, the English yachtsman Maurice Griffiths frequently shared anchorages in eastern England river estuaries with fleets of Thames barges awaiting a northerly wind to head south to London. One memorable September dawn, after a long, stormy night in the sheltered Orwell River, he woke to the sound of clanking windlasses as dozens of waiting barges raised sail to an unexpected northwesterly wind. Within minutes, brown spritsails crowded the river in a long line down to the North Sea. Some of the barges had been in the anchorage for a week, waiting out the strong headwinds.