Arthur Lyon Dahl of Geneva, Switzerland, is a biologist (AB, Biological Sciences, Stanford University; PhD, Biology, University of California, Santa Barbara) and environmentalist with 50 years’ international experience in environment and sustainability. He is a retired Deputy Assistant Executive Director of the United Nations Environment Programme (UNEP), where he was Deputy Director of the Oceans and Coastal Areas Programme, and Coordinator of the UN System-wide Earthwatch. He is a consultant on sustainability indicators and assessment to the World Bank, the World Economic Forum, UNESCO and UNEP. He was a Visiting Professor, University of Brighton, working on values-based indicators of education for sustainable development, and for 12 years has taught advanced studies courses in sustainable development and environmental diplomacy at the University of Geneva and other universities. He participated in the United Nations Conference on Human Environment in Stockholm (1972), was in the Secretariat of the Rio Earth Summit (1992) to help draft Agenda 21; and participated in the World Summit on Sustainable Development (Johannesburg 2002) and the UN Conference on Sustainable Development (Rio+20, 2012). He co-coordinated the UNEP Major Groups and Stakeholders Advisory Group on International Environmental Governance prior to Rio+20. A specialist on small islands and coral reefs, he spent many years in the South Pacific and organized the Secretariat of the Pacific Regional Environment Programme (SPREP). He is President of the International Environment Forum and on the governing board of ebbf – Ethical Business Building the Future.  He has published many scientific papers and books including “The Eco Principle: Ecology and Economics in Symbiosis”.