Hans Joachim (“John”) Schellnhuber is a German atmospheric physicist, climatologist and founding director of the Potsdam Institute for Climate Impact Research (PIK) and former chair of the German Advisory Council on Global Change (WBGU). As founding director of PIK, he led the institute from 1991 until 2018. From 2001 to 2005, he was also research director at the Tyndall Centre for Climate Change Research in Great Britain. Among other science academies, he is a member of the Pontifical Academy of Sciences, the German National Academy Leopoldina, the US National Academy of Sciences, the Academia Europaea, and the Academy of Athens. He received, inter alia, the German Environment Prize (2007), the Volvo Environment Prize (2011) and the Blue Planet Prize (2017). He served as scientific advisor to a number of eminent political and religious leaders, including the German Chancellor Angela Merkel, European Commission President José Manuel Barroso and Ursula Von der Leyen, and Pope Francis. He also contributed in various ways to the Intergovernmental Panel on Climate Change (IPCC) that received the Nobel Peace Prize in 2007.