In today's world, we face complex challenges. Science is increasingly requested to find approaches to help to overcome them. But what kind of knowledge and research can help to address such complex societal challenges? Transdisciplinary research is increasingly seen as a promising approach to achieve this goal, as it integrates different perspectives, including different academic disciplines and non-academic knowledge. It brings together scientists, decision-makers, and affected people to analyse the problems, develop what they envision as desirable futures, and work on strategies and actions supporting the necessary changes.