text: **Appendix A**
  
  #agw, short for anthropogenic global warming, indicating global warming is caused by 
  
  human activities. 
  
  #cdnpoli, short for Canadian politics 
  #cop21, the yearly session of COP (short for the Conference of the Parties) held in 2015. 
  #cop24, the yearly session of COP (short for the Conference of the Parties) held in 2018. 
  #epa, short for the United States Environmental Protection Agency founded in 1970, an agency 
  
  aiming at protecting environment. 
  
  #gop, short for Grand Old Party, the Republican political party in the United States. 
  #nyc, short for New York City 
  #p2, short for Progressives 2.0, a hashtag used to show progressive political standpoints on Twitter. 
  #parisagreement, Paris Agreement, the agreement signed on UNFCCC in 2016 to deal with global 
  
  warming by reducing greenhouse gas emissions. 
  
  #sdgs, short for Sustainable Development Goals, containing 17 global goals put forward by the 
  
  United Nations General Assembly in 2015 and expected to be achieved in 2030. 
  
  #tcot, short for Top Conservatives On Twitter, a hashtag used to show conservative political 