This thesis investigates the potential of transmedia storytelling to engage the public in climate action through a detailed examination of the transmedia project “The YEARS Project”. Employing the transmedia design analytical and operational model by Gambarato et al. (2020) and the engagement model by Elizabeth Evans (2019), this study combines both frameworks to develop a new model focused on transmedia activism. The research identifies how the integration of diverse narrative techniques in the project and multimedia platforms can enhance awareness and mobilize action among audiences, whilst also highlighting significant challenges that limit its effectiveness and global reach. Accessibility challenges, such as subscription requirements and language barriers, coupled with a US-centric approach, limit the project's global applicability and restrict content primarily to English-speaking audiences targeting mainly the Global North. Further, the project lacks dedicated community-building platforms beyond social media and clear calls to action within the frame of the project's core, the documentary series. By proposing a model for transmedia activism, this thesis provides valuable insights and strategic guidelines for practitioners aiming to design factual transmedia storytelling projects that drive civic action and thereby enhance the under-researched field of transmedia activism.