A Very Definite Past Meets an Unfortunately Possible Future: Review of The Great Warming by Brian Fagan
In the aftermath of Hurricane Sandy, certain recent, widely-reported comments remind me that I have put off for too long a review of a very important book by Brian Fagan on the last period of global warming, AD 800-1300. For example, New York State Governor Andrew Cuomo notes the increasing frequency and severity of storms as a present and future reality that needs to be faced. New York City Mayor Michael Bloomberg cites global warming out-right as the root problem associated with the recent increase in severe storms. Over the last week I have heard many people remark that we are having “100-year storms” every year or two. In Schenectady, New York, the Sunday Gazette recently carried a story (subscription required) on the problem (with memories of the devastation of tropical storms Irene and Lee along the Mohawk River and Schoharie Creek still all too recent).
History is instructive regarding human dilemmas and their resolution, and Brian Fagan has given us The Great Warming: Climate Change and the Rise and Fall of Civilizations (Bloomsbury Press, 2008) to chronicle a wide variety of human responses to the last great episode of global warming, separated from our own recent experience by the several centuries of that remarkable cooling trend, the Little Ice Age (AD 1300-1850). The great warming has been called the Medieval Warm Period since the British climate historian Hubert Lamb coined this term in the mid-20th century. Lamb’s thesis that such a period existed was based upon his study of European historical documents. More recently, other data have been brought into the study of ancient climate, including a broader review of old texts, plus a diversity of scientific data from analyses of tree-ring sequences, ice cores extracted from glaciers, and tropical coral growth layers. Fagan couples this information with historical and archaeological data on cultures that inhabited many parts of the world during the Medieval Warm Period in order to determine how humanity was affected, and how different people– with diverse cultures and living in radically different environments– developed ways to adjust to dramatic climate change.
This is fascinating reading, although I will not indulge my temptation to go into specific methodological or cultural details in this review. At the same time, however, it is necessary to be aware that Fagan tells not one but two great stories in this book. The first is the story of beneficial effects of climate change that allowed some populations to grow, some ways of life to flourish, and some civilizations to flower. For example, this is the story of the growth of European civilization coming out of the Dark Ages, its agricultural base stimulated by good weather, its population booming, its treasuries overflowing, its Gothic cathedrals rising toward heaven (It is also the story of the greening of the Arctic fringe and migration of Viking communities across theNorth Atlantic). As beneficial as this period was for agriculture and pastureland, however, food shortages became acute due to demographic and social factors; and social, strategic and technological innovations were necessary.
The other story is the tale of how much of the rest of the world dried out as temperatures rose and rainfall patterns changed. Human populations on several continents were adversely affected. We learn in the these chapters of the effects of drought in the West African Sahel, California, the American Southwest, Mesoamerica, the Andes, India, China, and the steppes of Eurasia. We learn of the pervasive problem of water shortages in those places so long ago. Fagan teaches us about the interplay between long-term trends such as medieval warming and short term cyclical phenomena such as El Niño and La Niña, and fluctuating regional forces such as monsoons. We read of tragedy and a variety of human responses, not the least of which have included the abandonment of homelands, migration, and intersocietal conflict.
Is there a message or lesson for the present in this study of the Medieval Warm Period? Fagan offers several. One is that we shouldn’t take the fact that there was a Medieval Warm Period as evidence that the current warming is simply a natural fluctuation, rather than an effect of humanity’s recent heavy consumption of fossil fuels. Fagan argues that the age of serious denial of human-caused global warming is long over. But it is instructive to know that there was an earlier time when global warming caused big problems, significantly shaping world history due to the ways that various societies responded. And if you happen to be someone who remains skeptical of the human role in global warming, Fagan’s book is just as instructive that global warming, whatever its cause, is a problem that needs to be addressed.
Other lessons of the Medieval Warm Period are summarized in Fagan’s last chapter, “The Silent Elephant”. Here he relates the historical situation to the modern as he outlines the major environmental problems of global warming, including rising sea-level, storms of increasing intensity, and drought. Stating that the Medieval Warm Period may more aptly be known as “the Medieval Drought Period”, Fagan focuses on drought and water shortages as a particularly pernicious problem that will continue to develop with increasing impact due to current global warming. And in contrast to the Medieval Warm Period, when many societies remained unconnected to each other, the world today is highly interconnected, and the problems of distant regions can have broad economic, social and political effects. Fagan urges his readers to be aware of the potential extent and significance of drought in many parts of the world with continued global warming.
In New York State, where we have recently (and justifiably) become more aware than ever of the issues of increasing storm severity, great floods, and rising sea-level, we are largely unaware of a piece of ancient historical data on drought that Fagan mentions in his last chapter: drought conditions in eastern New York during the Medieval Warm Period significantly decreased the flow of fresh water into the Hudson River, allowing salinity to rise in the long Hudson estuary. He notes: “If similar conditions were to prevail in the same area today, the water supply of millions of people would be endangered…” This presumes longer droughts than known in recent history, as the great droughts of the Medieval Warm Period documented in other parts of North Americawere multi-decadal to multigenerational in duration.
A world-renowned archaeologist, Brian Fagan has made it his calling to interpret archaeology to the reading public. He has given us a terrific read in The Great Warming, and has followed the relationships between climate and cultural history in several other books including Floods, Famines, and Emperors (on the effects of monsoons and El Nino cycles), The Little Ice Age: How Climate Made History, 1300-1850, and The Long Summer: How Climate Changed Civilization (reviewed in Fieldnotes, July 23, 2012).