People’s knowledge and beliefs about intangible problems such as climate change rely heavily on mediated discourses of science and policy. This thesis employs a dialogical and rhetorical approach to social representations to examine how two mediating systems -the mainstream press and environmental non-governmental organizations- represent and reconstruct climate change. The first empirical chapter focuses on the articles published over one decade (1999-2009) in the mainstream Turkish press. The analyses reveal that climate change emerged as a matter of public concern after 2005 in relation to the ecological extremes faced with in the country (Study 1), and that high levels of dramatization in the press in this national context were achieved by drawing on these local impacts and dire risks, and divorcing them from the global and political aspects of the problem (Study 2). Through this separation between the global and the local, and by reconstructing an image of solid scientific knowledge, a hegemonic representation of a serious ‘human-caused threat’ was established, without identifying by whom or how it would be dealt with (Study 3). The second empirical chapter focuses on the interviews (N=22) with non-governmental actors involved in climate change information and policy in Turkey and Portugal. The analyses show that when responding to less reflexive tasks, the non-governmental experts also confine themselves to the hegemonic representation: ‘a human caused problem’ (Study 4). Yet, in their reflexive representations, they focus more on the solutions to the problem, bringing into play, contrasting and reconciling two more representations: ‘an environmental problem’ and ‘a socio-political problem’ (Study 5). It is shown how these representations interfere with each other in two argumentative contexts, in which the interviewees organized the points of agreement and disagreement in a way which makes their views more acceptable to others (Study 6). Overall, these studies show that, in pursuit of persuasion, the mainstream press mainly resorted to a unifying threat and to emotions, whereas the non-governmental actors resorted to negotiation and reconciliation of divergent views.