Drawing on a dataset of tweets relating to the COP26 summit in Glasgow and COP27 summit in Sharm El-Sheikh, this paper investigates the networks of interaction between participants in the online debate. Distinguishing between @mentions, retweets, quote tweets, and other forms of interaction, it examines the agonistic alliances and antagonistic animosities between participating groups of Twitter users, and from this identifies patterns of polarisation within the climate change debate, and their evolution over the duration of the summits.