When we think "climate change," we think of man-made global warming, caused by greenhouse gas emissions. But natural climate change has occurred throughout human history, and populations have had to adapt to its vicissitudes. Tony McMichael, a renowned epidemiologist and a pioneer in the field of how human health relates to climate change, is the ideal guide to this phenomenon, and in his magisterial Climate Change and the Health of Nations, he presents a sweeping and authoritative analysis of how human societies have been shaped by climate events.
Some have theorized that natural environment determines the fate of communities. McMichael does not go that far, but he emphasizes that it does have vast direct and indirect repercussions for human health and welfare. After providing an overview of the dynamics of global warming and the greenhouse effect, McMichael takes us on a tour of the entirety of human history, through the lens of climate change. From the very beginning of our species some five million years ago, human biology has evolved to adapt to cooling temperatures, new food sources, and changing geography. As societies began to form, they too evolved in relation to their environments, most notably with the development of agriculture eleven thousand years ago. McMichael dubs this mankind's 'Faustian bargain,' because the prosperity and comfort that an agrarian society provides relies on the assumption that the environment will largely remain stable; in order for agriculture to succeed, environmental conditions must be just right, which McMichael refers to as the 'Goldilocks phenomenon.' Now, with global warming, the bill is coming due-not that it was ever far out of mind. Climate-related upheavals are a common thread running through history, and they inevitably lead to conflict and destruction. McMichael correlates them to the four horsemen of the apocalypse: famine, pestilence, war, and conquest. Indeed, they have precipitated food shortages, the spread of infectious diseases, and even civilizational collapse. We can see this in familiar historical events-the barbarian invasions of Rome, the Black Death in medieval Europe, the Irish potato famine, maybe even the Ten Plagues-that had their roots in natural climate change.
Why devote so much analysis to the past, when the terrifying future of climate change is already here? The story of mankind's survival in the face of an unpredictable and unstable climate, and of the terrible toll that climate change can take, in fact could not be more important as we face the realities of a warming planet. This sweeping magnum opus is not only a rigorous, innovative, and fascinating exploration of how the climate affects the human condition, but also a clarion call to recognize our species' utter reliance on the earth as it is.