text: Although global warming is linked to abnormal weather phenomena, temporal analysis suggests 
  their associations were not innate or changeless. An increase in association strength was observed in 
  2012 according to Figure 4. Two reasons may have contributed to this change. Firstly, the Hurricane 
  Irene and Hurricane Sandy, two serious extreme weather events in 2011 and 2012, were proven to 
  raise the volume of climate-related tweets and evoke the public’s consciousness of global warming 
  [2] to some extent. However, Sandy may not be the only reason. Studies that analyzed the discourse 
  of three extreme events on Twitter pointed out that political and ideological debates, rather than 
  phenomenon-related discussions, dominated during Sandy, evidenced by hashtag “#sandy” not being 
  even to the temperature and extreme weather cluster (red in Figure 4), but was identiﬁed to the cluster 
  describing hesitation between climate facts and actions (yellow in Figure 4). 
  
  After examining every associated node in the red cluster in 2012, we suggest that the hashtag 
  “2012” in the top right-hand corner, which is the only event-based hashtag, can provide another 
  hint about why the associations related to temperature and extremeweather signiﬁcantly increased 
  in 2012. The Maya inscriptions about the end of the world in December 2012 were prevalent then, 
  and even inspired a famous American disaster ﬁlm named “2012”, telling a story that the earth 
  would be destroyed by a series of disastrous extreme natural events. Previously, historians focused 
  on the correlations between climate issues and the collapse of the Mayan civilization [96,97], but no 