From the inbox:
I was recently thinking of majors of study, and was wondering what field of Science would compliment economics? I am considering either Ecology or Earth Sciences. I see Earth Sciences the obvious path to go down ..., but I like the idea of trying to price a polar bear or something. Would you have any insight into which would be better internationally?
I don't really know but my guess is that ecology would be the best major to pair with economics if you want to value a polar bear (or do any bioeconomic stuff). Earth Sciences would be great to better help understand the economic theory of the mine, Hotelling's Rule, land use and hedonic housing markets but it seems the mining companies would want to assign a $0 value to the polar bear.
Any better answers from commenters?