Brian D. Fath is a Professor in the Department of Biological Sciences at Towson University (Maryland, USA) and a Senior Research Scholar at the International Institute for Applied Systems Analysis (Laxenburg, Austria). He has published over 180 research papers, reports, and book chapters on environmental systems modeling, specifically in the areas of network analysis, urban metabolism, and sustainability. He has co-authored the books A New Ecology: Systems Perspective (2020), Foundations for Sustainability: A Coherent Framework of Life-Environment Relations (2019), and Flourishing within Limits to Growth: Following Nature's Way (2015). He is also Editor-in-Chief for the journal Ecological Modelling and Co-Editor-in-Chief for Current Research in Environmental Sustainability. Dr. Fath was the 2016 recipient of the Prigogine Medal for outstanding work in systems ecology and twice a Fulbright Distinguished Chair (Parthenope University, Naples, Italy, in 2012 and Masaryk University, Czech Republic, in 2019). In addition, he has served as Secretary General of the International Society for Ecological Modelling, Co-Chair of the Ecosystem Dynamics Focus Research Group in the Community Surface Modeling Dynamics System, and member and past Chair of the Baltimore County Commission on Environmental Quality. Sven E. Jorgensen (1934-2016) was a Professor of Environmental Chemistry at Copenhagen University. He earned a doctorate of engineering in environmental technology and a doctorate of science in ecological modeling. He was an honorable doctor of science at Coimbra University (Portugal) and at Dar es Salaam (Tanzania). He was Editor-in-Chief of Ecological Modelling from the journal's inception in 1975 until 2009. He was Editor-in-Chief for the Encyclopedia of Environmental Management (2013) and Encyclopedia of Ecology (2008). In 2004, Dr. Jorgensen was awarded the Stockholm Water Prize and the Prigogine Medal. He was awarded the Einstein Professorship by the Chinese Academy of Sciences in 2005. In 2007, he received the Pascal Medal and was elected a member of the European Academy of Sciences. He published over 350 papers and has edited or written over 70 books. Dr. Jorgensen gave popular and well-received lectures and courses in ecological modeling, ecosystem theory, and ecological engineering worldwide.