Duck Duck Book

32 – long summer
04.24.2006, 5:33 pm
Filed under: science

The long summer : how climate changed civilization / Brian Fagan.
New York : Basic Books, c2004.
[MCL call number: 551.6 F151L 2004; two copies, no holds]

When I was in grade school, I was taught about the Ice Age.  I learned that the Ice Age was an era many thousands of years ago when mastodons lived in Europe and North America, and nearly the entire earth was wrapped in cold, cold, cold.  Our ancestors hunted for their living, and supplemented their diets with the few plant foods available (which were very, very few in the northern hemisphere).  After the Ice Age, things warmed up, people developed agriculture, and civilization began.

Well, like most things taught in grade school, the relationship between the development of civilizations the history of the earth’s climate is much more complex than this.  In The Long Summer, Brian Fagan begins with the premise that human innovations to survive climatic stress (such as agriculture, irrigation, cities, and large scale political alliances) have done very well for us in times of moderate climate change, but have set us up for disaster when large changes come.

For example, healthy hunter-gatherer societies employ a strategy of mobility, shifting to neighboring regions when their environment is no longer able to support them comfortably.  But people have these big brains, just waiting to be used.  In many different parts of the world, hunter-gatherer societies responded to greater-than-average climate change by cultivating plants to provide a more steady supply of food.  This move made it possible for larger groups of people to live in one place, and in turn increased food security to a degree that allowed for population growth.  When the next horrific shift in the weather came (drought, rain at the wrong season, cold weather, whatever), people weren’t able to change their strategy so nimbly as before.  In some places, the next round of innovation raised the stakes again — people developed more intense systems of agriculture with irrigation, double-cropping, and practices to increase soil fertility, all so that they would be able to feed larger populations, and even support whole classes of people who didn’t work to provide food (or who didn’t work at all).  We have, Fagan asserts, boldly undertaken innumerable further innovations that protect us in the short term, but make us ever more vulnerable to really big events of weather and climate change.  Careful attention to recent weather events makes this thesis seem very plausible.

While explaining the detail of this story of innovation and risk, Fagan takes readers through a history of how the climate has shifted colder and warmer in the northern hemisphere, and how that affected our ancestors there, always with an eye toward explaining the consequences of dry and wet periods, hot weather, winds, ocean currents, and cold, and how these phenomena have influenced vegetation, rivers and lakes, sea levels, animal populations, and people’s ability to survive in the ever changing landscape.  Fagan explains complex scientific theories smoothly, and his writing is engaging and instructive.  The Long Summer is well worth your time, especially if your understanding of the history of climate change is limited to what you learned in elementary school, as mine was when I picked up this book.


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