Smith's research investigates global change, soils, carbon sequestration, climate change and climate change mitigation. Since 1996, he has served as convening lead author, lead author and author for part of the IPCC Fourth Assessment Report published by the Intergovernmental Panel on Climate Change, which was awarded the 2007 Nobel Peace Prize. He is a global ecosystem modeller with interests in agriculture, food security, bioenergy, greenhouse gases and greenhouse gas removal technologies.