He has worked intensively since 1975 on a range of global economic, development and environmental issues as a diplomat, international civil servant, Director of Greenpeace International, and Strategic Director of the Global Reporting Initiative (GRI). Now an independent consultant, his clients include governments, intergovernmental agencies, business and non-profit organizations. Trained as an international lawyer, Hohnen worked from 1975 to 1989 as an Australian diplomat at the OECD in Paris, to the EU institutions in Brussels, and in Fiji and Sri Lanka. He was closely involved in the 1992, 2002 and 2012 Earth Summit processes, and has participated in the negotiation of a wide range environmental convention, including on climate change. Hohnen conducts executive level workshops on embedding sustainability in business strategies and is an expert on materiality and sustainability reporting.