William Ruddiman is a professor emeritus at the University of Virginia. Ruddiman initially trained as a marine geologist at Williams College and Columbia University and then worked on past climate changes at Columbia’s Lamont-Doherty Earth Observatory and the University of Virginia. He has investigated ice-age cycles in North Atlantic sediments and has examined the global cooling over the last 50 million years. With Maureen Raymo (Columbia University), Ruddiman proposed the uplift of Tibet drove that cooling and created the strong seasonally alternating monsoons that dominate Asia today. Since 'semi-retiring' in 2001, he has explored the climatic role farmers played during the last several thousand years by generating greenhouse gases from agriculture.