I'm an IR/PS grad from 2010. I was searching for an unrelated topic and this thread popped up.
I just want to clarify that IR/PS has a very strong environmental program. The international environmental policy track is one of the fastest growing tracks at IR/PS and we have great faculty in that area - David Victor, Josh Graff Zivin, Junjie Zhang, Jen Burney, and others. Actually the faculty in this track in particular are some of the strongest at IR/PS. During the first year of the MPIA program, students take mostly core classes, with maybe a few electives in their regions/career tracks. In the core classes you learn all the quant and policy skills that you need to be able to handle the 2nd year classes. The second year of the program is when you really explore your chosen career track. If someone only attended in the fall, they wouldn't have had little, if any, experience with the career track.