Water Scarcity
My usual warning bell to ring is Peak Oil, but there are plenty of other issues out there as well. It really just comes down to scarcity, Energy, Food, Water. Energy, and therefore oil, is of course heavily used in manufacturing and distribution of goods. I think that this is pretty well understood. But another commodity that is used in many industrial processes is water. I’ve been running across that more because of the extensive use of water in shale oil extraction. But it is also true in all other forms of manufacturing (and agriculture) too. The BBC News has a neat info graphic and article that shows how much fresh water goes into each item you buy. None of those were too shocking to me, but I bet I would be amazed on things like cars and houses. Need to try to find that chart on the internet.
(IIRC, My wife showed me a site that shows different amounts of water going into different foods a while back. Clearly the higher up the food chain you eat the more water you are going to need, but there were some outliers as well. I’ll post a link to that chart too if I can find it again.)