The annual United Nations (UN) Framework Convention on Climate Change conferences provides a transnational mediation opportunity structure for activist networks to contest policies that favor market-based models for solving the climate crisis. Online technologies, including commercial social media, have arguably increased possibilities for being involved in protests on a transnational level. However, this article shows how online modes of action privilege lobbying tactics over civil disobedience tactics, arguing that the former is often incommensurate with an anticapitalist climate approach to climate change activism. This impedes possibilities for using online media to protest at the radical end of the climate justice movement spectrum. This article explores this interrelationship between activist demands and (online) modes of action through a focus on the mobilization efforts of London-based activists for the 17th UN climate conference in 2011.