This paper applies some of the major concepts and methods that Ron Scollon developed in order to analyse how discourses of environmental citizenship, sustainability and climate change are mediated in a global media event. ‘Earth Hour’ began in 2007 in Sydney, Australia, and in 2009 it was proclaimed a successful global event. The event focused primarily on citizen awareness, participation and solidarity in mitigating climate change. In its sister campaign (‘Vote Earth’), the discourse of representative democracy was deployed to constitute an imaginary global electorate. The paper focuses on the analysis of: (a) the intense drive to visualize and spectacularize (mediational means) the simple act of switching off the lights and the consequences of such an act; (b) the massive infrastructure of discourse to synchronize the collective performance of a global ‘climate public’; (c) the discursive ‘memory work’ to archive and memorialize the hour, e.g. on YouTube; (d) the attempt to inculcate a ‘global citizen’ who is concerned with the environment/climate and whose anticipatory mediated actions in relation to it are prefigured by the event; and (e) the resistance to the circulation of this new mediated discourse.