TRUC is a collaboration of social, environmental and climate scientist as well as policy stakeholders. The project aims to develop and test a novel integrated framework to examine the interactions between large-scale coastal urbanization, environmental change and socio-economic vulnerability to extreme events (i.e. heat waves and flooding). The aim is to reveal the pathways and trade-offs through which systems interactions constrain or open opportunities for different adaptation paradigms and pathways, ranging from resistance to resilience and transformation. Funded by the Belmont Forum, TRUC is the only project within the coastal vulnerability stream that concentrates explicitly on megaurban areas. The project specifically focuses on Kolkata, Lagos, London, New York, and Tokyo. TRUC builds an original integrated, participatory framework in collaboration with stakeholders to first characterize and then identify interactions between bio-physical, land-use, and decision-making processes as well as socio-economic change. The project combines transdisciplinary analytical tools developed by the different consortium members: an integrated urban energy and water balance model (SUEWS), an urban flood model, an index-based representation of risk and vulnerability as well as a participatory scenario method to identify and evaluate potential vulnerability and adaptation pathways. UNU-EHS leads the component on the participatory scenario development which is conducted in each of the five cities and which brings together urban planning practitioners, risk managers and other civil servants with academic and civil society experts. The main objective of the TRUC scenario workshops is to develop and debate, in a participatory manner with stakeholders, different development and adaptation trajectories of the cities up to the year 2050. A stepwise scenario method is applied, specifically developed for TRUC. The resulting scenarios and the underlying storylines are within the TRUC project further utilized to inform quantitative risk modeling and scenarios assessments in each of the cities, lead by collaborators from the University of Reading, the University of Tokyo and the University of Stuttgart. The participatory scenario workshops allow to examine linkages between climate change adaptation and other overall development trajectories that are important to the countries and cities in the study, paying particular attention to past drivers of vulnerability (e.g. decline in social housing, uncontrolled urban sprawl or inadequate infrastructure). UNU-EHS further contributes to the development of the TRUC conceptual framework and the risk index.