The Great Warming

by Brian Fagan

  Arid and semiarid regions of the world today.

  Droughts are expensive in human terms and also carry a high economic price. The notorious Dust Bowl droughts of 1934–40 over the Great Plains scarred an entire generation. Three and a half million people fled the land. Many suffered from typhoid and other diseases, also long-term health effects like higher risks of cancer and heart disease, but exact casualty figures are not available. The midwestern drought of 1950 to 1956 brought extreme heat, ruined numerous farmers, and reduced crop yields in some areas by as much as 50 percent. The 1987–89 drought covered 36 percent of the United States, less than 70 percent of the area affected by the Dust Bowl, but with an estimated cost of $39 billion, which makes it one of the most expensive natural disasters in American history. The dry conditions fanned huge wildfires in the West and caused serious navigational problems due to drought-related shoaling in the upper Mississippi basin. As a comparison, and to give some insight into the potential costs of really huge future climatic disasters, 2005’s Hurricane Katrina has cost $81 billion so far, and that figure is rising.

  History tells us that droughts have long wreaked havoc, especially in the tropics. At desert margins and in semiarid environments, the pump effect comes into play as faltering rainfall pushes animals and people out to better-watered margins. In a telling analysis of nineteenth-century droughts, the historian Mike Davis has estimated, conservatively, that at least 20 million to 30 million people, and probably many more, most of them tropical farmers, perished from the consequences of harsh droughts caused by El Niños and monsoon failures during the nineteenth century, more people than in virtually all the wars of the century. The Victorian famines are relatively well documented, although, as Davis points out, his fellow historians often ignore them, for the victims who perished were mostly unlettered and their lives unrecorded.8

  The mortalities for earlier famines, like those that must have occurred during the Medieval Warm Period, are lost to history. An estimated 1.5 million medieval Europeans perished as a result of famine and famine-related diseases during the great rains of 1315–21, which ushered in the Little Ice Age. The casualties among Chinese peasants in the Huang He Valley, among farmers in the coastal river valleys of the Andes, and in the American Southwest must have been significant, especially since many people lived in crowded villages, towns, and pueblos with but rudimentary sanitation. Twentieth-century experience provides a point of comparison. The Chinese famine of 1907 killed an estimated 24 million people. Over 3 million perished in the drought of 1941–42. One and a half million Indians died in the famine of 1965–67, as a result of monsoon failure. Between a quarter of a million and 5 million Russians were victims of a drought in the Ukraine and Volga regions in 1921–22. All of these disasters occurred when global populations were much smaller than today. When one realizes that droughts in the sparsely inhabited Saharan Sahel claimed over 600,000 lives in the droughts of 1972–75 and again in 1984–85, one can only imagine what the magnitudes of these disasters would have been had farming populations been at today’s levels.

  I hadn’t realized until I researched this book just how remarkably flexible human societies were in much of the world a thousand years ago. During the Medieval Warm Period, a high proportion of the earth’s population lived in drier environments like those that had nurtured the first civilizations some five thousand years ago. Cities were much smaller, with populations numbering in the tens of thousands, not the millions, which made it easier to adopt strategies for riding out climatic shifts. Every society living in marginal environments for farming developed coping mechanisms. The Ancestral Pueblo of the American Southwest maintained kin ties with distant communities and were prepared to move when droughts came. The Maya stored water at the village and city level. Chimu lords in coastal Peru built elaborate canals and distributed irrigation water with sedulous care. Mande farmers in West Africa’s Niger basin developed complex social mechanisms that handled the realities of sudden climatic change, while California Indians stored acorns and depended on their neighbors to make up for food shortfalls.

  All of these societies, and others we’ve described in these pages, were vulnerable to drought. For the most part, with the notable exception of monsoon India and China, they rolled with the climatic punches like trees buffeted by a strong wind. Some environments, like the loess lands of northern China, were so unpredictable that famine was chronic even in years of good rainfall, when floods inundated and saturated thousands of acres of arable land. But in general the human societies of a millennium ago were less vulnerable than we are. There came a point, however, when a society reached a critical mass, a density of urban population and nonfarmers that was unsustainable in drought cycles, or an agricultural economy that had exhausted the land and all opportunities for diversification. The Maya of the southern lowlands of Mexico and Guatemala are a dramatic case in point, where a combination of endemic warfare, rigid governance, environmental degradation, and drought dealt a crippling blow to dozens of towns and great centers. The great lords and the mechanism of state disintegrated and the people dispersed into the subsistence farming villages of a thousand years before. We’re dazzled by the splendors of Angkor Wat and Angkor Thom in Cambodia, but, like the Maya, the Khmer lived on the edge of the slippery slope that led downward from self-sustainability.

  Fast-forward to the nineteenth century, to the height of Victorian imperial power, where threats to send a gunboat were a powerful diplomatic tool and the technologies of communication and transport— telegraph, steam, rail—infinitely more effective than those of medieval times. A global economy was emerging, founded in great part on grain prices. Yet the nascent vulnerability of the Medieval Warm Period increased a thousandfold. Mike Davis’s conservative estimate of twenty million to thirty million casualties sustained, for the most part on the dark, unwritten side of history, beggars the imagination. His figures are from a time when the proportion of the world’s population living in semiarid and monsoon lands was a fraction of what it is today.

  In the early twenty-first century, some 250 million people live on agriculturally marginal lands, at direct risk from droughts caused by ENSO events, by arbitrary swings of the Southern Oscillation. There are far more instances than those mentioned in earlier chapters. Northeastern Brazil has suffered from major droughts repeatedly, many of them caused by El Niños; Indonesia and Australia are at the mercy of ENSO droughts, to mention only three examples.

  Today, the number of people in the world who are highly vulnerable to drought is enormous and growing rapidly, not only in the developing world but also in densely populated areas such as Arizona, California, and southwestern Asia. Judging from the arid cycles of a thousand years ago, the droughts of a warmer future will become more prolonged and harsher. Even without greenhouse gases, the effects of prolonged droughts would be far more catastrophic today than they were even a century ago

  Droughts nurture crop failure and allow pastureland to dry out. The same droughts cause rivers to dry up and turn small streams into dry watercourses. Water is the lifeblood of humanity—for agriculture, for herds, for the animals people once hunted, and for drinking. The Chumash Indians of southern California suffered greatly during droughts, not because they lacked food, for they had plenty of fish, but because of a lack of clean water. Crowded into fishing camps and densely inhabited villages near increasingly scarce water supplies, they relied on polluted drinking water, with the inevitable onslaught of disease caused by poor sanitation. The same was true of the British Raj’s Indian famine camps in the late nineteenth century, also of ancient eastern Mediterranean cities.

  NOW, WITH WARMING accelerating, the stakes for humanity are much higher. Today, we harvest water on an industrial scale—from rainfall, from rivers and lakes, and from rapidly shrinking water tables. Many of us live off looted supplies, brought by aqueduct from the Owens watershed, culled from the Colorado River, and taken from artesian wells, aquifers that will one day run dry. With respect to
California, it’s sobering to remember that the past seven hundred years were the wettest since the Ice Age. We have experienced droughts, but none of them have endured like those that descended on the Sierra Nevada a millennium ago.

  Today, we are experiencing sustained warming of a kind unknown since the Ice Age. And this warming is certain to bring drought— sustained drought and water shortages on a scale that will challenge even small cities, to say nothing of thirsty metropolises like Los Angeles, Phoenix, and Tucson. The Ogallala aquifer, an enormous underground reserve that supplies eight states from Nebraska to Texas, is being depleted at a rate of 42 billion gallons a year. When one hears that an expanding Las Vegas is trying to buy up water supplies from outlying Nevada ranches, one wonders what the future will hold. Will a day come when the hotels on the Strip run out of water because the aquifers have run dry? In terms of water, if the lengthy droughts of a millennium ago were to return, much of the western United States is living on borrowed time.

  According to UNESCO, the world has plenty of fresh water, albeit unevenly distributed. But if you look more closely you’ll see that, owing to mismanagement, limited resources, and environmental change, almost one fifth of the world’s population still lacks access to safe drinking water. Forty percent do not enjoy basic sanitation. In raw figures, UNESCO estimates that 1.1 billion people do not have drinking water supplies, and about 2.6 billion lack basic sanitation.9 Over half of these people live in China and India, millions more in tropical Africa. These figures come at a time when natural disasters involving water, or its lack, are on the rise. By 2030, UNESCO also estimates, the world will need 55 percent more food, which translates into a growing demand for irrigation, which already claims 70 percent of all fresh water consumed by humans. Then there is the huge increase in urban populations. UNESCO researchers estimate that two thirds of humanity will be urban dwellers by 2030, an estimated 2 billion of them in squatter settlements and slums. The urban poor suffer the most from lack of clean water and sanitation.

  The lesson of the Medieval Warm Period for our time is subtle yet alarming. Our journey through the warm and drought-ridden world of a thousand years ago revealed a great diversity of human societies, many of them interconnected by ever-changing economic and sociopolitical ties.

  Our travels have taken us down the highways and seaways of a nascent global economy, through a world where interconnectedness and interdependency were beginning to become sustained political realities. We traveled through a time when, on the whole, people lived conservatively, with a good weather eye for risk. Now we confront a future in which most of us live in large and rapidly growing cities, many of them adjacent to rising oceans and waters where Category 5 hurricanes or massive El Niños can cause billions of dollars of damage within a few hours. We’re now at a point where there are too many of us to evacuate, where the costs of vulnerability are almost beyond the capacity of even the wealthiest governments to handle. The sheer scale of industrialized societies renders them far more vulnerable to such long-term changes as climbing temperatures and rising sea levels.

  This is the immediate crisis of global warming in human terms and it requires not a short-term response but massive intervention on a truly international, and long-term, scale.

  We’re not good at planning for our great-grandchildren, yet this is what is required of our generation and of those who follow us. There’s a political temptation to announce some short-term palliatives and then to claim that we have made a significant contribution to the battle against global warming. Unfortunately, we are past the moment when we can rely on short-term thinking. Drought and water are probably the overwhelmingly important issues for this and future centuries, times when we will have to become accustomed to making altruistic decisions that will benefit not necessarily ourselves but generations yet unborn. This requires political and social thinking of a kind that barely exists today, where instant gratification and the next election seem more important than acting with a view to the long-term future. And a great deal of long-term thinking will have to involve massive investments in the developing world, for those most at risk.

  We can’t afford to think in provincial terms, of only the drought problems in our own backyards. The warm centuries of a thousand years ago show us that drought is a global problem. Today, we’re all interconnected. The experience of the Medieval Warm Period shows how drought can destabilize a society and lead to its collapse. Today, destabilizing forces can jump local boundaries. If we look at how the chance to earn a better living has drawn millions from Latin America across U.S. borders, imagine how many people might uproot themselves if the choice were between famine and food. Many futurists believe the wars of coming centuries will not be fought over petty nationalisms, religion, or democratic principles, but over water, for this most precious of all commodities may become even more valuable than oil. They are probably correct.

  How much longer can we remain detached? What will today’s casualty figures be like if the droughts projected by the Hadley meteorologists come to pass? They’ll be catastrophic, far more so than nineteenth-century fatalities revealed by Mike Davis, and could produce frightening scenarios. Are we looking, for example, at a time when enormous, uncontrollable mass migrations of people fleeing hunger and drought will burst across territorial boundaries? Such population movements are not beyond the realm of possibility.

  It’s been easy for us to forget that millions of people still live at the subsistence level and use basically medieval technologies to wrest a living from the soil. We can no longer afford benign ignorance, for the long-term perils of chronic drought connect all humankind in ways that we are only just beginning to understand. In an earlier book, I described industrial society as a huge supertanker that takes many miles to stop and maneuvers slowly.10 I accused our society of being oblivious and inattentive, of ignoring the climatic danger signals that lie ahead.

  Thanks to a new generation of science and thanks to activists ranging from Al Gore to university students, global warming has become a political issue and a topic of fascination for the chatterers. Yet, it’s striking, and very frightening, that the elephant of drought is still so widely ignored.

  History is always around us, threatening, offering encouragement, sometimes showing us precedents. The warm centuries of a thousand years ago remind us that we have never been masters of the natural world; at our best, we have accommodated ourselves to its fickle realities. As the Khmer and the Maya show us, the harder we try to master it, the greater our risk of sliding down the hazardous slope of unsustainability. We should accept this reality and not be frightened by a future where we are not the masters; we must cease trying to assume that role. The people of a thousand years ago remind us that our greatest asset is our opportunism and endless capacity to adapt to new circumstances. Let us think of ourselves as partners with rather than potential masters of the changing natural world around us.

  Acknowledgments

  The Great Warming is the culmination of over a decade of thinking and writing about ancient climate change. It treats of a subject that is still little known, information about which is scattered in obscure academic literatures in dozens of languages. I’ve attempted to produce a synthesis that is very much my own take on a confusing jigsaw puzzle of archaeology, history, and paleoclimatology. I am, of course, responsible for the conclusions and accuracy of this book, and, no doubt, will hear in short order from those kind, often anonymous individuals who delight in pointing out errors large and small. Let me thank them in advance.

  The research for this book involved consulting a large number of busy specialists, who were invariably courteous and often startlingly prompt in their replies. I am deeply grateful to them for taking my importunings seriously. It’s impossible to name everyone, but my long list of indebtedness includes Reid Bryson, Roseanne D’Arrigo, Carole Crumley, Ronald Fletcher, Michael Glantz, Michael Glassow, John Johnson, Doug Kennett, Ian Lindsay, Roderick McIntosh, George Michaels, Dan Penny, Mark Rose
, Vernon Scarborough, Chris Scarre, Scott Stine, and Stan Wolpert.

  In Santa Barbara, Shelly Lowenkopf was my passionate foil and the best of writing coaches. He saw me through many tricky moments and was, as always, enthusiastic and supportive. Steve Brown drew the maps and drawings with his customary skill. Bill Frucht was extremely helpful in the early stages of the book. My debt to him is enormous. My agent, Susan Rabiner, was a tower of strength and inspiration.

  Peter Ginna and Katie Henderson provided editorial guidance when the manuscript was at its most critical stages. In a real sense, this is their book as much as mine. Their merciless and perceptive criticism made the final stages of writing much easier. I’m deeply grateful.

  Finally, and as always, my thanks to Lesley, Ana, and our menagerie, who have suffered through the pains of writing with amused tolerance. In fact, I’ve just been delayed for five minutes by a cat sitting on the keyboard demanding attention. Life is always interesting around here.

  Brian Fagan

  Santa Barbara, California

  Notes

  The literature on the societies described in these pages is enormous and growing rapidly, but is dwarfed by the current tidal wave of publications on ancient and modern climate change. New journals and books appear daily. Many of them are, of course, highly specialized and of little relevance to these pages. The references that appear below provide a good cross-section of the literature as of mid-2007 and contain useful bibliographies for those wishing to probe deeper.