Just a short thought, regarding sustainability books.
The Local Politics of Global Sustainability , the best book I've found so far about social sustainability, is filed in the Greenback library system under Library of Congress classification "HC 79".
HC 79 is the classification for "Economic history and conditions -- Special topics".
So the theme of the book is that the economy is embedded in (and thus fully dependent upon) society, while society is embedded in (and thus fully dependent upon) the natural environment. If what you're concerned with is creating an economy with a long (shelf) life, narrowing your focus to simply exchanges of labor for goods and services (especially if you only look at the exchanges that are monetized) isn't useful.
But in terms of library shelving, it's the economics that takes precedence and . . . even within economics . . . this whole topic is kind of an afterthought. Like automation. Or flow of funds.
I don't blame the librarians. They're faced with the problem of having to shelve a wide range of information in an antiquated, unidimensional, inflexible scheme. And the way western society has traditionally organized knowledge simply has no place for undisciplined subjects like sustainability.
But that's kind of the problem, isn't it?