William F. Ruddiman is apalaeoclimatologist andProfessor Emeritus at theUniversity of Virginia. Ruddiman earned an undergraduate degree ingeology in 1964 atWilliams College, and a Ph.D. inmarine geology fromColumbia University in 1969. Ruddiman worked at the USNaval Oceanographic Office from 1969 to 1976, and at Columbia'sLamont–Doherty Earth Observatory from 1976 to 1991. He moved toVirginia in 1991, serving as a professor in Environmental Sciences.[1] Ruddiman's research interests center onclimate change over several time scales. He is a Fellow of both theGeological Society of America and theAmerican Geophysical Union. Ruddiman has participated in 15 oceanographic cruises, and was co-chief of twodeep-sea drilling cruises.[1]
Ruddiman is best known for his 'early anthropocene' hypothesis (or 'Ruddiman hypothesis'), the idea that human-induced changes ingreenhouse gases did not begin in the eighteenth century with advent of coal-burning factories and power plants of theindustrial era but date back to 8,000 years ago, triggered by the intensefarming activities of our early agrarian ancestors.[2] 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 asMilankovitch 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).
Ruddiman is also known for his hypothesis in the 1980s that thetectonic uplift ofTibet created the highly seasonalmonsoonal circulation that dominates Asia today. With his then graduate studentMaureen Raymo he hypothesised that the uplift of the Himalayas and Tibetan Plateau caused a reduction in atmospheric CO2 through increases in chemical weathering and was therefore a major causal factor in the Cenozoic Cooling trend that eventually led to our most recent series ofIce Ages.[3]
He was awarded theLyell Medal of theGeological Society of London for 2010.[4]
He has written several books:Plows, Plagues, and Petroleum: How Humans Took Control of Climate, a textbook onclimate science,Earth's Climate, Past and Future,[1] and most recentlyEarth Transformed,[5] the subject of the2014 American Geophysical Union's Tyndall Lecture. He has published over 125 scientific papers.[6]
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