This is obviously not at all the concern that people have regarding overpopulation.

But problem is resource consumption, no?

It's a complete speculation, because I can't cite this, but isn't Earth not capable of sustaining 7+ billion people? Exponential population growth brings even greater exponential rise of greenhouse effect, oil consumption, deforestation, etc. IMHO it is the main problem of overpopulation.

Nobody knows what its capable of sustaining. There's stuff like using resources more efficiently, recycling etc. We aren't good at these things yet, consumption could go a lot higher with improvements to those.

> We aren't good at these things yet, consumption could go a lot higher with improvements to those.

That's an Malthusianism[0] right here. Why recycling and increased efficiency themselves aren't a solution? Because people will increase their consumption to offset all the gains.

C.f.:

"Why are even some affluent parts of the world running out of fresh water? Because if they weren’t, they’d keep watering their lawns until they were."

[0] - http://www.scottaaronson.com/blog/?p=418

Increasing consumption isn't necessary a bad thing.

And you need space to plant stuff to feed everyone. Can 11m² be enough to feed an average person through the whole year?

The rest of Europe has more than enough farmland to provide for 7 billion people, calorie-wise. If we were to learn how to farm on the open sea, back of the envelope calculations tell me we should easily be able to multiply today's population by 10^4 or more.

If there is a problem, it's water. On the plus side, water is the easiest to recycle by far, the only limit we're close to hitting in some locations is the amount of water that's recycled for free by the weather.

Also, we have skyscrapers. The 11m2 area per person is ground-level area. If you have 10-storey skyscrapers on average, 120m2 for every family on average should be easy, and allow for population to increase 5 fold without exceeding available space in Austria.