Quitting a PhD program and reapplying to a different (though somewhat related) field?

Question

Back in my original cycle, I applied right out of undergrad for a couple of programs that I initially thought could fit my interests well. All of them ended up falling into two fields, Engineering or Earth/Climate Science, and I got into some good programs for earth science (e.g. Stanford and Berkeley). I ended up deciding to go to UPenn for Engineering since I thought I might enjoy the work there better but as I'm going through the motions, I feel like I'm not as into the specific research area my advisor is dealing with as I thought I'd be. I'm beginning to think I'd have enjoyed going into climate science instead a lot more, which is probably not the best conclusion to come to at this point...

My current department doesn't have a whole lot of faculty working in this specific area anyways - even the climate science department doesn't seem like it has a ton of projects I'd be interested in. I'm thinking of Master-ing out and potentially reapplying to some climate science programs instead. I haven't consulted my advisor on this yet. Additionally, I'm keeping up on my current research project/classes, and I intend to continue to do so until I officially leave, so it's not like I'm underperforming/slacking.

I'm wondering how exactly one would fare in this whole reapplication process. I presume my undergrad application was strong enough that I got into a couple of good programs so I would think a Master's plus additional research would surely add to that. I am worried on two accounts, however:

1. How exactly would my current advisor take the news that I'd like to explore a different field altogether? Let's assume I continue to do well, make good progress in terms of research, and get good grades, blah blah: would they be pissed? Should they be pissed? How should I break the news to them while ensuring the letter isn't tainted by some sort of vendetta?

2. How should I mention this on my application? And how should I approach the application process in general? A simple Google search tells me that most new programs I'd apply to would eye my application rather suspiciously if I do not have a "good reason" for leaving and that advisors might be wary of taking me on if I Master'd out since "what's stopping me from doing the same when I get to their program". Is it really that big of a hurdle? I'd like to think that changing interests, especially to a field that is not too far off from my current one, is a decent reason but I'd be curious to hear opinions.

Answer 1

1. From what I heard, switching topics are okay in research. My supervisor told me that you should not feel stuck with one topic your supervisor got you into. So, I suppose they should take it philosophically. Perhaps it isn't even the first such situation they encounter.
2. Generally, it is s good thing to have a story in your application or even CV. If you can frame it as a story, even failures might feature you in a good light. Try to tell about the switch in terms of revelation, of finally finding your passion. Tell them how your whole life pushed you to this particular point in time and this decision. You will be quite convincing like this.