Dennis Tirpak has worked on climate change since 1985. He was the Director of Global Change Policy Division at the US Environmental Protection Agency; the Coordinator of Science and Technology at the United Nations Secretariat for the Framework Convention on Climate Change (UNFCCC) and Head of the climate change unit at the Organization for Economic Cooperation and Development (OECD). He was one of the coordinating lead authors of Chapter 13 of the Intergovernmental Panel on Climate Change. He currently is an Associate with the International Institute of Sustainable Development in Canada and a Principal Advisor at the World Resources Institute.