data source: http://cdiac.ornl.gov/ftp/ndp030/CSV-FILES/
From global ems file and nation ems file, we know that:
for national data:
All emission estimates are expressed in thousand metric tons of carbon.
for global data:
All emission estimates are expressed in million metric tons of carbon.
except for per capita data, it's same in both file:
Per capita emission estimates are expressed in metric tons of carbon.
Because concepts from nation file and global file are mostly the same but with different scales, we unify them by multiplying global data by 1000, so they both have same units. (Except for per capita data, we don't change the values in both files)
One ton of carbon equals 44/12 = 11/3 = 3.667 tons of carbon dioxide