I have three plus years of ESL teaching experience in Africa and Asia including work as an instructor at a top University in Asia.... do I still need a teaching certificate to teach in Dubai? I have a BA...

Your BA plus 3 years experience should be enough to secure you a teaching position in Dubai. Of course, the more you have to offer in terms of qualifications and experience, the better your chances of landing a well paid job with opportunities for advancement. However what you can currently offer is more than adequate at entry level. Not sure if you know, but Desert Speak is a forum that deals with employment issues in Dubai, it might be worth checking out.

Good luck