According to Irvin Baxter, Jr.  the pale horse of Revelation should really be a green horse, or pale green horse.  The word in Greek is Chloros (spelling ?).   It is one of the root words of chlorophyll.  My son-in-law who has studied Greek, confirmed this with his concordance.
 
What does green mean today?
 
Green is the main color of Islam.  It is on many flags of the Middle East and was supposedly Mohammed's favorite color.
 
Also, it seems like the whole world has embraced the ecological religion of being "green".