text: The association networks of #climatechange and #globalwarming are shown in Figure 2. Nodes 
  are labelled with the hashtags and the undirected edges are weighted to reﬂect the frequency of 
  co-occurrence. The modularity analysis identiﬁed four clusters in the #climatechange network and 
  ﬁve in the #globalwarming network, where clusters are diﬀerentiated by color (resolution is 0.75 for 
  climate change and 0.85 for global warming). The theme, top hashtags, and the proportion of each 
  cluster are also summarized and represented in the network depicted in Figure 2. 
  
  The largest cluster (green nodes) of both #climatechange and #globalwarming network refer 
  to general facts about global climate issues, sharing words about the causes or eﬀects concerning 
  sustainability. The diﬀerence is that the largest cluster of #globalwarming (46% of the network) includes 
  more slogan words, such as “world”, “planet”, “global”, and “climatechangeisreal”, whereas the 
  largest cluster of #climatechange (40% of the network) tends to discuss some speciﬁc problems, such as 
  agriculture, biodiversity, education, and politics. 