Lexical combinations of at least two roots around 'carbon' as the lexical hub, such as 'carbon finance' or 'carbon footprint', have recently become ubiquitous in discourses on climate change in English speaking science, politics, and mass media. They are part of a new language evolving around the issue of climate change that can reveal how it is framed as a public issue by various stakeholders, how public attitudes and perceptions are shaped and which solutions to climate change and global warming are being proposed, contested and debated. In this article, we study the role of some of these 'carbon compounds' as tools of communication in different online discourses dealing with issues of climate change mitigation. By combining a quantitative diachronic analysis of their occurrences with a qualitative analysis of the contexts in which the compounds were used, we identify three clusters of compounds focused on finance, lifestyle, and attitudes, and then elucidate the different communicative purposes to which they were put between the 1990s and the early 21st century, reflecting a temporal shift in the debate. This approach may open up new ways of analyzing the different framings of climate change mitigation initiatives in the public sphere.