Climate change as a complex physical and social issue has gained increasing attention in the natural as well as the social sciences. Climate change research has become more interdisciplinary and even transdisciplinary as a typical Mode‐2 science that is also dependent on an application context for its further development. We propose to approach interdisciplinarity as a co‐construction of the knowledge base in the reference patterns and the programmatic focus in the editorials in the core journal of the climate‐change sciences—Climatic Change—during the period 1977–2013. First, we analyze the knowledge base of the journal and map journal–journal relations on the basis of the references in the articles. Second, we follow the development of the programmatic focus by analyzing the semantics in the editorials. We argue that interdisciplinarity is a result of the co‐construction between different agendas: The selection of publications into the knowledge base of the journal, and the adjustment of the programmatic focus to the political context in the editorials. Our results show a widening of the knowledge base from referencing the multidisciplinary journals Nature and Science to citing journals from specialist fields. The programmatic focus follows policy‐oriented issues and incorporates public metaphors.