Regarding such a complex issue as climate change, it is crucial to understand how specialised knowledge is conveyed to the public. The Intergovernmental Panel on Climate Change (IPCC) is often considered the main source of scientific knowledge on climate change. This paper aims at understanding how knowledge produced by the IPCC is disseminated in three types of documents, with various degrees of specialisation, Earth Negotiation Bulletins, United Nations reports and the general-interest press, over two time periods (2009-2010 and 2014-2017). To do so, the analysis combines the tools of corpus linguistics and discourse analysis, which puts quantitative results in context. Identifying IPCC collocates enables to specify the context of use according to sub-corpora. This reveals that although the IPCC is referred to as a knowledge-provider in all corpora, there are variations as to the degree of trustworthiness given to the institution as well as to the amount of detail given on results. Looking at explicit quotations according to their theme, wording and type of reported speech confirms this. Recontextualization processes in the press corpora entail more reformulation and explanatory comments. The scientific nature of the work is made more explicit in the United Nations reports and Earth Negotiation Bulletins. Differences between the six sub-corpora can be analysed according to generic specificities and time frames revealing the increasingly central role of the IPCC as a trustworthy provider of scientific knowledge on climate change.