William F. Ruddiman is retired from the University of Virginia, USA and has since concentrated his research on the climatic role farmers played during the last several thousand years by clearing land, raising livestock, and irrigating rice padis. Over the course of his career, Ruddiman has explored several different aspects of the field of paleoclimate - from orbital-scale changes in North Atlantic sediment to the cause of long-term cooling over the last 50 million years. He has written trade books and numerous journal articles.