W.W. Norton & Company, Inc., 2011We may be human because we figured out how to use more energy than the 100 W that burns within us from the food we eat. Certainly, we hadn’t been human for very long before we learned to benefit from extra outside energy, with some of the wealthier of us now using more than 10,000 W apiece.

The switch from a hunter-gatherer lifestyle to agriculture gave us more food, but we have remained hunter-gatherers of external energy, collecting and burning wood, whales, or whatever we could get. We have always burned more of these than nature could supply. Even with Ben Franklin’s amazing stove, trees didn’t grow fast enough to fuel his fellow citizens of Pennsylvania. Burning whales for light was wiping them out when there were far fewer people than now, and when many of those people were illuminating with other, cheaper...

Earth spent a few hundred million years storing fossil fuels that hold much more energy than the available trees or whales. As we mastered hunting and gathering of coal, oil, and natural gas, we used more energy than ever while allowing trees and whales to grow back.

Good things almost always produce unintended consequences, and fossil-fuel use has been no exception. Sherlock Holmes sought criminals through the “opalescent London reek” or the “greasy, heavy brown swirl…condensing in oily drops upon the window-panes,” a result especially of coal-burning in the city. The witches in Shakespeare’s Macbeth chanting, “Fair is foul, and foul is fair: Hover through the fog and filthy air,” may have been referencing the coal-fired pollution of London as well as the coming tragedy. The burning of soft-bituminous “sea coal” grew rapidly in London as wood disappeared near the city, beginning probably in the 1100s. The smoke from this sea coal was so bad that King Edward I banned its burning in 1306. This didn’t work—in the chill of a London winter people wanted warmth, and with wood and cleaner-burning anthracite coal too expensive, the people found something to burn. Later, the huge increase in burning that came with the Industrial Revolution generated worse coal-smoke fogs that sometimes remained for months.

Nearly a millennium was required to solve the smog/fog problem in London, which finally cleared in the second half of the twentieth century. The history of our burning is even written in the layers of Greenland’s ice sheet, which show levels of acid-rain sulfate and black carbon rising greatly during the Industrial Revolution, and first black carbon and then acid rain largely being cleaned up in the North Atlantic basin in the twentieth century. Clearly, we can pollute, and we can clean up after ourselves.

Cleaning up the worst of the immediate problems from fossil fuels has allowed us to burn more with less damage. We still suffer the damages from acid rain, soot, mercury, uranium, and other by-products of the burning, and from coal-mine cave-ins, oil-well blowouts, acid mine drainage, and mountaintop removal that accompany our hunting and gathering, but we as a society have decided that the benefits outweigh the costs.

The material released by fossil-fuel burning is grossly dominated by CO2. At first, CO2 may not seem like an especially alarming by-product—it is essential for life, after all, and is around us all the time. Yet, as the early physician Paracelsus stated in the sixteenth century, “All things are poison and nothing is without poison, only the dose permits something not to be poisonous.” This is often simplified to “the dose makes the poison.” If you were to chat with someone who barely escaped drowning and then with someone who has faced the desert without water, you would surely learn that too much as well as too little of something can be bad.

Richard Alley is Evan Pugh Professor of Geosciences at The Pennsylvania State University. He has enjoyed his experiences working for an oil company and participating in the Intergovernmental Panel on Climate Change, which shared the Nobel Peace Prize with Al Gore in 2007. He is an elected member of the US National Academy of Sciences and the recipient of several awards for teaching, research and service.

Excerpted from EARTH: The Operators’ Manual by Richard B. Alley. Copyright © 2011 by Richard B. Alley, Geoffrey Haines-Stiles, and Erna Akuginow. With permission of the publisher, W.W. Norton & Company, Inc.

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