To cope with seemingly unstructured complex problems such as climate change, which do not have a single solution, it is necessary to nurture "sustainable citizens" with eight sustainable key competencies, as outlined in a UNESCO report (UNESCO 2017). To nurture such competencies, climate change education focusing on capacity building plays an important role.

  This paper focuses on the idea of utilizing the "Mystery" learning method (Leat 2001) to improve 'systems thinking competency' in the field of climate change education. To meet this objective, we first develop and implement a Climate Change Education (CCE) capacity building program suitable for specific Japanese climate change situations. Secondly, we assess the change in each participant's systems thinking competency. Finally, we analyze the participants' results and evaluate the effectiveness of the program.

  As a result, we observed improvement in the participants understanding of the relationship among elements that cause climate change, and the complexity and interdependence of climate-related systems. Based on these results, it is suggested that a CCE program using 'Mystery' is effective for improving the systems thinking competency of individuals.