Global tourism is a complex system, embedded within a dynamic framework and exposed to manifold trends, which may be perceived as challenges for the global tourism system. Exploratory research on the conditions and impacts of this field of intertwined challenges is needed as a prerequisite for future planning and tourism management. A reliable and shared knowledge on the nature of these challenges is essential. Our exploratory Delphi survey, carried out with an international panel of tourism experts, contributes to this task. We identified the most prominent challenges for global tourism until 2020, along with their drivers and impacts. We propose a structure of five “meta-challenges” that shows the complexity of the future global tourism system. Our structure may serve as a strategic road map for global tourism in a complex and dynamic world, allowing tourism managers to prepare for these challenges and to cope with them in a responsible way.