William Ruddiman

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William F. Ruddiman is a palaeoclimatologist and Professor Emeritus at the University of Virginia. He is known principally for his "early anthropocene" hypothesis, the idea that Human-induced changes in greenhouse gases did not begin in the eighteenth century with advent of coal-burning factories and power plants of the industrial era, but date back to 8,000 years ago, triggered by intense farming activities of our early agrarian ancestors. It was at that time that atmospheric greenhouse gas concentrations stopped following the periodic pattern of rises and falls that had accurately characterized their past long-term behavior, a pattern which is well explained by natural variations in the Earth’s orbit known as Milankovitch cycles. In his overdue-glaciation hypothesis Ruddiman claims that an incipient ice age would probably have begun several thousand years ago, but the arrival of that scheduled ice age was forestalled by the activities of early farmers.

The overdue-glaciation hypothesis has been challenged on the grounds that alternative explanations are sufficient to account for the current warm anomaly without recourse to human activity, but Ruddiman challenges the methodology of his critics. (see external links)

William Ruddiman is also known for his hypothesis in the 1980s that the tectonic uplift of Tibet created the highly seasonal monsoonal circulation that dominates Asia today.

He has also proposed that the uplift of the Tibetan and Colorado plateaus caused a reduction in atmospheric CO₂ and was therefore a major causal factor in the Cenozoic Cooling trend that eventually lead to our current Ice Age^[1]

He has written a number of books including "Plows, Plagues, and Petroleum: How Humans Took Control of Climate".