I recently finished my masters in environmental science, which was diffeq heavy, and got a position working with energy data and doing some economic modeling and operations research. I was a bit surprised that the project I came into doesn't seem to use any diffeq in its broad pieces, although it's possible I just haven't come across it yet.

We're doing most of our analysis in python with the scipy stack, so maybe I'll try a couple ODE-based projections this afternoon.