Since the 70's our economy's supposed to have gotten pretty efficient with energy, relatively. This is not to say there are not more gains to be made (cutting that fat, I suppose), but we should be safer than the past.

Is the recent hikeup hitting energy intensive economies (China) hard? It would make sense.

Uhm. If we're already pretty efficient, doesn't that make us more vulnerable to the Extremely Clueless Physicist's scenario, not "safer"? Fat people should do better in famines, no?