Yes, and when you're a child your caloric intake and your yearly increase in height are very tightly correlated too. Lots of society is built around this growth, such as the expectation of having to buy bigger clothes every year. But even a child can understand that one day they will stop growing and eat approximately the same amount of food for the rest of their life.

It would be "strange" to argue that, as a teenager, you were doomed to a life of misery because in order to keep up with this so-far exponential growth rate you'd have to eat entire planets by the time you were 1000 years old. It is similarly bizarre to argue that human society is in some sort of trouble because we can only double our energy consumption a few dozen more times.

This isn't even bringing up economic concepts like diminishing returns to utility: a person who makes 100k per year does not spend twice as much energy as someone who makes 50k per year. There are plenty of other things to buy that make us happy, and that can only get even more true when we're living in some hypothetical future with hundreds of times the economic productivity of today.

Humans run through a well-understood lifetime cycle of growth, maturity, and decline. Contemporary orthodoxy neoclassical economics doesn't generally recognize this, though it's beginning to. See Tim Worstall at the Telegraph UK: "Infinite growth on a finite planet? Easy-peasy!" http://blogs.telegraph.co.uk/finance/timworstall/100017248/i...

On the other side, Robert Gordon's "End of Growth" paper: http://www.voxeu.org/article/us-economic-growth-over

Your assertion that a person earning 100k doesn't have twice the energy (or environmental) footprint of someone earning 50k really needs some sort of factual support.

And your hypothetical future with 100s of times today's economic productivity flies in the face of the law of diminishing returns which you've invoked yourself.