text: **6. Conclusions**
  
  As social media is gradually overtaking the role of legacy media providing a forum for public 
  discussion, the semantic associations contained in social media discussions reﬂect and reinforce how 
  individuals portray global climate issues. By examining hashtag co-occurrence patterns on Twitter 
  between 2009 and 2018, we identiﬁed distinct climate perceptions hidden behind two competing 
  climate discourses and discovered how these two discourses evolved. 
  
  We found that broad scientiﬁc, social, political, and international discussions are the topics 
  of public climate discourse. Although the semantic diﬀerence between climate change and global 
  warming seems subtle, the diﬀerences in their cognitive associations are not trivial. Despite some 
  shared concerns between the two discourses, “global warming” is more politicized and focuses more on 
  general phenomena, especially temperature abnormalities, whereas climate change is a more compact 
  topic with a more scientiﬁc perspective and tends to refer to speciﬁc issues. The temporal analysis 
  revealed that traditional political discussions decreased in both discourses but climate change started to 
  build a discourse alliance with diverse domestic issues to show political intentions. Global warming’s 
  associations to extreme events and temperature change were suddenly strengthened around 2012. 
  Climate change is becoming dominant compared with global warming in public discussions. Although 
  the two discourses are becoming increasingly similar in the rank order of climate concepts, a notable 
  discrepancy still exists in the way in which they get concepts associated. These observations may 
  provide climate communicators with theoretical and practical hints to narrow the discrepancy between 
  diverse climate perceptions. 