Hi

We understand your concerns. Well, ese ( environmental science and engineering ) at IIT Bombay is A course with total duration of five years with Btech and Mtech in the course. It is a decent field, particularly if you want to pursue a career in research activities. If you are interested in this branch specially towards environment studies, you must opt for it, lest you can take many core branches like computer science, electrical,mechanical , civil in other renowned  old iits on this rank.

Hope this helps!!!