He recently served the Intergovernmental Panel on Climate Change (IPCC) where he was lead author of Guidelines for National Emissions Inventories (2006), lead on for the Special Report on Carbon Capture and Storage, contributing author on Radiative Forcing of Climate Change for the First Assessment Report, lead author on Energy Primer for the Second Assessment Report, lead author on Land-Use Change and forestry for the Third Assessment Report, and lead author on Special Report on Land-Use, Land-Use Change and Forestry. He currently serves as a editorial board of the Environmental Science and Policy Journal and editorial advisory board for the Mitigation and Adaptation Strategies for Global Change Journal.