The Little Ice Age

PREFACE

April 1963: The waters of the Blackwater River in eastern England were pewter gray, riffled by an arctic northeasterly breeze. Thick snow clouds hovered over the North Sea. Heeling to the strengthening wind, we tacked downriver with the ebb tide, muffled to our ears in every stitch of clothing we had aboard. Braseis coursed into the short waves of the estuary, throwing chill spray that froze as it hit the deck. Within minutes, the decks were sheathed with a thin layer of ice. Thankfully, we turned upstream and found mooring in nearby Brightlingsea Creek. Thick snow began to fall as we thawed out with glasses of mulled rum. Next morning, we woke to an unfamiliar arctic world, cushioned with silent white. There was fifteen centimeters of snow on deck.

Thirty-five years later, I sailed down the Blackwater again, at almost the same time of year. The temperature was 18˚C, the water a muddy green, glistening in the afternoon sunshine, skies pale blue overhead. We sailed before a mild southwesterly, tide underfoot, with only thin sweaters on. I shuddered at the memory of the chilly passage of three decades before as we lazed in the warmth, the sort of weather one would expect in a California spring, not during April in northern Europe. I remarked to my shipmates that global warming has its benefits. They agreed.…

Humanity has been at the mercy of climate change for its entire existence. Infinitely ingenious, we have lived through at least eight, perhaps nine, glacial episodes in the past 730,000 years. Our ancestors adapted to the universal but irregular global warming since the end of the Ice Age with dazzling opportunism. They developed strategies for surviving harsh drought cycles, decades of heavy rainfall or unaccustomed cold; adopted agriculture and stock-raising, which revolutionized human life; founded the world’s first preindustrial civilizations in Egypt, Mesopotamia, and the Americas. The price of sudden climate change, in famine, disease, and suffering, was often high.

The Little Ice Age survives only as a dim recollection: depictions in school textbooks of people dancing at fairs on a frozen River Thames in London in the jolly days of King Charles II; legends of George Washington’s ragtag Continental Army wintering over at Valley Forge in 1777/78. We have forgotten that only two centuries ago Europe experienced a cycle of bitterly cold winters, mountain glaciers in the Swiss Alps were lower than in recorded memory, and pack ice surrounded Iceland for much of the year. Hundreds of poor died of hypothermia in London during the cold winters of the 1880s, and soldiers froze to death on the Western Front in 1916. Our memories of weather events, even of exceptional storms and unusual cold, fade quickly with the passing generations. The arid statistics of temperature and rainfall mean little without the chill of cold on one’s skin, or mud clinging to one’s boots in a field of ruined wheat flattened by rain.

We live in an era of global warming that has lasted longer than any such period over the past thousand years. For the first time, human beings with their promiscuous land clearance, industrial-scale agriculture, and use of coal, oil, and other fossil fuels have raised greenhouse gas levels in the atmosphere to record highs and are changing global climate. In an era so warm that sixty-five British bird species laid their eggs an average of 8.8 days earlier in 1995 than in 1971, when brushfires consumed over 500,000 hectares of drought-plagued Mexican forest in 1998 and when the sea level has risen in Fiji an average of 1.5 centimeters a year over the past nine decades—in such times, the weather extremes of the Little Ice Age seem grotesquely remote. But we need to understand just how profoundly the climatic events of the Little Ice Age rippled through Europe over five hundred momentous years of history. These events did more than help shape the modern world. They are the easily ignored, but deeply important, context for the unprecedented global warming today. They offer precedent as we look into the climatic future.

Speak the words “ice age,” and the mind turns to Cro-Magnon mammoth hunters on windswept European plains devoid of trees. But the Little Ice Age was far from a deep freeze. Think instead of an irregular seesaw of rapid climatic shifts, driven by complex and still little understood interactions between the atmosphere and the ocean. The seesaw brought cycles of intensely cold winters and easterly winds, then switched abruptly to years of heavy spring and early summer rains, mild winters, and frequent Atlantic storms, or to periods of droughts, light northeasterlies, and summer heat waves that baked growing corn fields under a shimmering haze. The Little Ice Age was an endless zigzag of climatic shifts, few lasting more than a quarter century. Today’s prolonged warming is an anomaly.

Reconstructing the climate changes of the past is extremely difficult, because reliable instrument records are but a few centuries old, and even these exist only in Europe and North America. Systematic weather observations began in India during the nineteenth century. Accurate meteorological records for tropical Africa are little more than three-quarters of a century old. For earlier times, we have but what are called proxy records reconstructed from incomplete written accounts, tree rings, and ice cores. Country clergymen and gentleman scientists with time on their hands sometimes kept weather records over long periods. Chronicles like those of the eighteenth-century diarist John Evelyn or monastery scribes are invaluable for their remarks on unusual weather, but their usefulness in making comparisons is limited. Remarks like “the worst rain storm in memory,” or “hundreds of fishing boats overwhelmed by mighty waves” do not an accurate meteorological record make, even if they made a deep impression at the time. The traumas of extreme weather events fade rapidly from human consciousness. Many New Yorkers still vividly remember the great heat wave of Summer 1999, but it will soon fade from collective memory, just like the great New York blizzard of 1888, which stranded hundreds of people in Grand Central Station and froze dozens to death in deep snowdrifts.

A generation ago, we had a generalized impression of Little Ice Age climate compiled with painstaking care from a bewildering array of historical sources and a handful of tree-ring sequences. Today, the scatter of tree-ring records has become hundreds from throughout the Northern Hemisphere and many from south of the equator, too, amplified with a growing body of temperature data from ice cores drilled in Antarctica, Greenland, the Peruvian Andes, and other locations. We are close to a knowledge of annual summer and winter temperature variations over much of the Northern Hemisphere to as far back as A.D. 1400. Within a few years, these records will go back deep into the Middle Ages, perhaps to Roman times. We can now track the Little Ice Age as an intricate tapestry of short-term climatic shifts that rippled through European society during times of remarkable change—seven centuries that saw Europe emerge from medieval fiefdom and pass by stages through the Renaissance, the Age of Discovery, the Enlightenment, the French and Industrial revolutions, and the making of modern Europe.

To what extent did these climatic shifts alter the course of European history? Many archaeologists and historians are suspicious of the role of climate change in changing human societies—and with good reason. Environmental determinism, the notion that climate change was a primary cause of major developments like, say, agriculture, has been a dirty word in academia for generations. You certainly cannot argue that climate drove history in a direct and causative way to the point of toppling governments. Nor, however, can you contend that climate change is something that you can totally ignore. Throughout the Little Ice Age, and even as late as the nineteenth century, millions of European peasants lived at the subsistence level. Their survival depended on crop yields: cycles of good and poor harvests, of cooler and wetter spring weather, could make a crucial difference between hunger and plenty, life and death. The sufficiency or insufficiency of food was a powerful motivator of human action, sometimes on a national or even continent-wide scale, with consequences that could take decades to unfold. These same climatic verities still apply to millions of people living in less developed parts of the world.

In The Little Ice Age I argue that human relationships to the natural environment and short-term climate change have always been in a complex state of flux. To ignore them is to neglect one of the dynamic backdrops of the human experience. Consider, for instance, the food crises that engulfed Europe during the Little Ice Age—the great hunger of 1315 to 1319, which killed tens of thousands; the food dearths of 1741; and 1816, “the year without a summer”—to mention only a few. These crises in themselves did not threaten the continued existence of Western civilization, but they surely played an important role in the formation of modern Europe. We sometimes forget how little time has passed since Europeans went hungry because of harvest failure. Some of these crises resulted from climatic shifts, others from human ineptitude or disastrous economic or political policy; many, like the Irish potato famine of the 1840s, from a combination of all three—and a million people perished in that catastrophe. Its political consequences are still with us.

Environmental determinism may be intellectually bankrupt, but climate change is the ignored player on the historical stage. This is partly because of a long-held and erroneous assumption that there were few significant climatic shifts over the past millennium that could possibly have affected human societies, and also because few archaeologists or historians have followed the extraordinary revolution in paleoclimatology over the past quarter-century. Now we know that short-term climatic anomalies stressed northern European society during the Little Ice Age, and we can begin to correlate specific shifts with economic, social, and political changes, to try to assess what climate’s true impact may be. (I focus on northern Europe in these pages, because this is the region that was most directly affected by atmospheric/ocean interactions during the Little Ice Age and where climatic data are most abundant. The effects on Mediterranean lands are still little understood.)

The Little Ice Age is a narrative history of climatic shifts during the past ten centuries and some of the ways in which people in Europe adapted to them.

The book is divided into four parts. Part One describes the Medieval Warm Period, roughly A.D. 900 to 1200. During these three centuries, Norse voyagers explored northern seas, settled Greenland, and visited North America. William the Conqueror invaded England and the pious embarked on a frenzy of cathedral building. The Medieval Warm Period was not a time of uniform warmth, for then, as always since the Great Ice Age, there were constant shifts in rainfall and temperature, at least one caused by a great volcanic eruption in the tropics during the year 1258. Mean European temperatures were about the same as today, perhaps slightly cooler.

Tree rings and ice cores tell us that Little Ice Age cooling began in Greenland and the Arctic in about 1200. As the Arctic ice pack spread southward, Norse voyages to the west were rerouted into the open Atlantic, then ended altogether. Storminess increased in the North Atlantic and North Sea. Colder, much wetter weather descended on Europe between 1315 and 1319, when thousands perished in a continent-wide famine.

By 1400, the weather had become decidedly more unpredictable and stormier, with sudden shifts and lower temperatures that culminated in the cold decades of the late sixteenth century. Fish were a vital commodity in growing towns and cities where food supplies were a constant concern. Dried cod and herring were already the staples of the European fish trade, but changes in water temperatures forced fishing fleets to work further offshore. Part Two, “Cooling Begins,” tells how the Basques, Dutch, and English developed the first offshore fishing boats adapted to a colder and stormier Atlantic, vessels like the English dogger, capable of venturing far offshore in the depths of February gales to catch fish near Iceland and eventually on Newfoundland’s Grand Banks. The cod trade led fleets across the Atlantic and helped sustain the first North American colonists.

In the sixteenth century, Europe was still a rural continent, with the most rudimentary of infrastructures and a farming population that lived from harvest to harvest. Monarchs everywhere wrestled with the problem of feeding their people at a time when climatic misfortune was attributed to divine vengeance and human sin. The colder weather of the late sixteenth century particularly threatened communities in the Alps, where glaciers advancing down mountain valleys destroyed entire communities and overran their fields. Northern Europe suffered through exceptional storminess. The great gales of August 1588 destroyed more of the Spanish Armada fleet than the combined guns of English warships.

Part Three, “The End of the ‘Full World’,” tells the story of a gradual agricultural revolution in northern Europe that stemmed from concerns over food supplies at a time of rising populations. The revolution involved intensive commercial farming and the growing of animal fodder on previously fallowed land. It began in Flanders and the Netherlands in the fifteenth and sixteenth centuries, then spread to England in Stuart times—a period of constant climatic change and often intense cold. Many English landowners embraced the new agriculture as larger enclosed farms changed the face of the landscape and new crops like turnips provided protection for herds and people against winter hunger. The increased productivity from farmland made Britain self-sufficient in grain and livestock and offered effective protection against the famines of earlier times.

In France, however, the nobility had little concern for agricultural productivity. Despite some centers of innovation, France remained agriculturally backward in the midst of a deteriorating climate that made bad harvests more frequent. By the mid- to late eighteenth century, when much of Europe was growing larger quantities of produce, most French farmers were exceptionally vulnerable to food dearths resulting from short-term climatic shifts. Millions of poor farmers and city dwellers lived near the edge of starvation, as much at the mercy of the Little Ice Age as their medieval predecessors. But it was not until the politicization of the rural poor after the poor harvest of 1788 that reform began with the French Revolution.

When Mount Tambora in southeast Asia erupted in 1815, it created the famous “year without a summer” and widespread hunger. Cool, unpredictable weather continued into the 1820s and 1830s, when the first signs of agricultural problems surfaced in Ireland. During the seventeenth and eighteenth centuries, the Irish had embraced the potato as a dietary staple. By the early nineteenth century, Ireland exported her oats to England, and her poor lived almost exclusively on potatoes. With the inevitability of Greek tragedy, blight savaged the potato crop after 1845.

Part Four, “The Modern Warm Period,” covers the end of the Little Ice Age and the sustained warming of modern times. The mass emigration fostered by the Irish famine was part of a vast migration from Europe by land-hungry farmers and others not only to North America but much further afield, to Australia, New Zealand, and southern Africa. Millions of hectares of forest and woodland fell before the newcomers’ axes between 1850 and 1890, as intensive European farming methods expanded across the world. The unprecedented land clearance released vast quantities of carbon dioxide into the atmosphere, triggering for the first time humanly caused global warming. Wood also fueled the early stages of the Industrial Revolution in the United States, adding to rising levels of greenhouse gases. Global temperatures began to rise slowly after 1850. They climbed more rapidly in the twentieth century as the use of fossil fuels proliferated and greenhouse gas levels continued to soar. The rise has been even steeper since the early 1980s, with record-breaking summer heat and mild winters during the 1990s. The Little Ice Age has given way to a new climatic regime, marked by prolonged and steady warming, with no signs of a downturn. At the same time, extreme weather events like Category 5 hurricanes and exceptionally strong El Niños are becoming more frequent.

The lessons of the Little Ice Age are twofold. First, climate change does not come in gentle, easy stages. It comes in sudden shifts from one regime to another—shifts whose causes are unknown to us and whose direction is beyond our control. Second, climate will have its sway in human events. Its influence may be profound, occasionally even decisive. The Little Ice Age is a chronicle of human vulnerability in the face of sudden climate change. In our own ways, despite our air-conditioned cars and computer-controlled irrigation systems, we are no less vulnerable today. There is no doubt that we will adapt again, or that the price, as always, will be high.

AUTHOR’S NOTE

All measurements in this book are given in metric units. A meter is slightly longer than a yard, and sixteen kilometers is roughly ten miles. Water freezes at 0˚ Centigrade and boils at 100˚C. An ideal temperature to be outdoors is about 25˚C (77˚ Fahrenheit).

Place names are spelled according to the most common usages. Archaeological sites and historical places are spelled as they appear most commonly in the sources used to write this book.

Nonmeteorologists and nonsailors should note that wind directions are described, following common maritime convention, by the direction they are coming from. A westerly wind blows from the west. Ocean currents, however, are described by the direction they are flowing toward. Thus, a westerly wind and a westerly current flow in opposite directions.