text: 5.1.3. Discourse Structure 
  
  In the discourse surrounding #climatechange, “environment”, “energy”, and “global action” 
  represented the themes of the three largest clusters in the network. However, three popularly recurring 
  hashtags, “#environment”, “#energy”, and “#climateaction”, did not belong to any of the three clusters 
  above, but formed another small tight cluster together, sitting in the most central part of the semantic 
  network, as shown in Figure 2b. As each of the three hashtags can almost represent one sub-theme of 
  the climate change topic and these three hashtags were tightly bundled might indicate an attempt by 
  #climatechange users to address all three communities together [91], consolidating climate change as 
  a topic rather than a loosely organized topic. Previous communication studies also conﬁrmed hashtags’ 
  function of serving as a hybrid forum [68], where heterogeneous individuals coordinate to solve 