Two independent clauses may be joined by using a semicolon before a conjunctive adverb.
When you use a conjunctive adverb (like however, therefore, or consequently) to connect two independent clauses, you typically place a semicolon before the conjunctive adverb and a comma after it. For example:
"I wanted to go for a walk; however, it started to rain."
Using a comma before a conjunctive adverb is not correct in this case.