Skeptic: Promoting Science and Critical Thinking

The impact on climate from 200 years of industrial development is an everyday fact of life, but did humankind’s active involvement in climate change really begin with the industrial revolution, as commonly believed? Dr. William Ruddiman, a climate scientist at the University of Virginia in Charlottesville and the author of the controversial new book, Ploughs, Plagues, and Petroleum, argues that humans have actually been changing the climate for some 8,000 years—as a result of the earlier discovery of agriculture. The “Ruddiman Hypothesis” has been controversial ever since it was featured as a cover story in Scientific American. It states that the impact of farming on greenhouse-gas levels, thousands of years before the industrial revolution, kept our planet notably warmer than if natural climate cycles had prevailed — quite possibly forestalling a new ice age.

Ruddiman takes us through three broad stages of human history: when nature was in control; when humans began to take control, discovering agriculture and affecting climate through carbon dioxide and methane emissions; and, finally, the more recent human impact on climate change. Along the way he raises the fascinating possibility that plagues, by depleting human populations, also affected reforestation and thus climate — as suggested by dips in greenhouse gases when major pandemics have occurred. He concludes by looking to the future and critiquing the impact of special interest money on the global warming debate.