A comma indicates a pause between the ending of an introductory word, phrase, or clause, and the beginning of the main part of the sentence.
# A comma is used before any coordinating conjunction (and, but, for, or, nor, so, yet) that links two independent clauses. ....
#It is also used after a dependent clause that starts a sentence. ...
#Commas also used to offset appositives from the rest of the sentence. ...
#They are used to separate items in a series. (this is the most commonly used)
You can take "in fact" out of the sentence to help with determine what type of sentence it is because it's a prepositional phrase. This leaves us with "Only a small percentage of Southern Africa is desert" which is a simple sentence.
there is not space to enumerate all his works
