text: In some cases, social media users have long struggled to deﬁne the most appropriate hashtag for 
  certain events [60,66]. By observing the usage pattern of trending hashtags “#CrimingWhileWhite” and 
  “#AliveWhileBlack” in a struggle against racism, [67] discovered that two related hashtags generated 
  in a single event will draw public attention to diﬀerent sides of a story and cause noticeable structural 
  and linguistic diﬀerences in public discourse. 
  
  When hashtags are used in combination with each other, their co-occurrence pattern in big data 
  can hint to the cognitive associations in people’s thoughts [60,68]. Researchers can extract nonlinear 
  social media narratives [69] and discover the networked frame crowdsourced by the public [61]. In the 
  ﬁeld of climate communication, co-occurrence of environment and social-political hashtags is thought 
  to strengthen the associations between a variety of trans-regional issues in protests and build collective 
  action frames [70]. The role of climate change issues in the Australian federal election was also 
  discovered with a co-hash analysis [71]. Reference [72] examined how hashtags concerning science, 
  political campaigns, geographical discussions, societal concerns, and new technologies co-occurred 
  with “IPCC”, oﬀering a broad context for studying IPCC communication on social media. 