This paper explores where greenhouse gases (GHGs) like carbon dioxide (CO2) come from and how they are emitted by different countries. CO2 is a major player in global warming, making up most of the GHGs that are warming our planet. Humans are a big reason for the rapid rise in GHGs, which is heating up the Earth. Many countries and groups are working to figure out how to reduce these emissions. The researchers found that China was the biggest emitter of CO2 in 2013. The study used a method where they collected information about the different sources of GHGs, which can be natural or caused by humans.