Arnold, a national of Austria, has many years of professional experience in the field of environmental law, diplomacy and policy. He believes in making sure that environmental law and governance deliver for people and the planet. Arnold joined UNEP in 2005 and advanced work on important issues such as environmental crime, human rights and the environment, judges and the environment, freshwater law and governance, and, most recently, in response to attacks on environmental defenders. Under his leadership the international community and stakeholders began to advance the notion of environmental rule of law. In 2012 he led the planning and organization of the first World Congress on Justice, Governance and Law for Environmental Sustainability as part of the UN Conference on Sustainable Development (Rio+20).
Before joining UNEP, Arnold has worked in the governmental, non-governmental and in the private sector.
He holds a doctorate degree in international environmental law from the University of Vienna as well as a master's degree in advanced international studies from the Diplomatic Academy of Vienna.