As linguists, we are interested in the way uncertainty, understood as a range of epistemic qualities related to not knowing, is dealt with linguistically in communicative contexts involving scientists, the mass media and the public. One of our central theses is that uncertainty in journalistic texts is not only reflected at different linguistic levels but that it also has various rhetorical functions. Through close analysis of a German newspaper article about geo-engineering, we show which specific linguistic forms, categories and structures are used when dealing with uncertainty, and which rhetorical functions of uncertainty are identifiable in the text. We conclude from our analysis that a ‘language of (un-)certainty’ is always highly context sensitive, meaning that the linguistic resources used to express uncertainty are both multifaceted and multifunctional.