CO2       
noun [ U ] (also CO2) uk/ˌsiː.əʊˈtuː/ us/ˌsiː.oʊˈtuː/
 二氧化碳的分子式
the chemical symbol for carbon dioxide; used to refer to the substance carbon dioxide
  The global pandemic of coronavirus has temporarily cut global emissions of CO2. 冠状病毒的全球大流行暂时减少了全球二氧化碳的排放量。 
 They set new CO2 reduction targets. 他们制定了新的二氧化碳减排目标。 
 - More examples
 - CO2 concentrations in the atmosphere are at their highest levels in over 800,000 years.
 - The USA is a net importer of CO2.
 - The pandemic could cause emissions cuts this year in the region of 2,000m tonnes of CO2.
 - Here is some data on CO2 and other greenhouse gas emissions.