Ok, now this gets more complicated, but I'll follow...

Consider Peak Oil: it's not necessarily how long that oil lasts, but the flow rate that counts...

So, less oil (and natural gas, because we're running into that wall too) means less energy...

And less energy means that the flow of things derived from energy (even if it has absolutely nothing to do with oil/gas) also is reduced.

Less N, P, K from around the world because the 'energy flow' (i.e. energy needed for transportation) is restricted by energy;

Less food because the 'energy flow' (i.e. energy needed to run tractors, water pumps, etc) is less;

Less water because the 'energy flow' (i.e. energy needed to pump wells from aquifers) is less;

Less synthetic fertilizer (I-NPK) because the 'energy flow' (i.e. energy needed to create the chemicals needed for fertilizers) is less...

I guess it is all about flows. If you have 3 million people living in a city, and only enough food to feed 1.5 million is flowing in, you have problems. If you have only enough heat or electricity to heat and provide for 1.5 million, you have problems. If you only have enough water for 1.5 million, again, problems.

Flows...