Our food is made of non-renewable resource.
Every year, we use:
* 105m tons per year of nitrogen-based (natural gas) fertilisers[1]
* 22m tons per year of phosphate-based (mineral based) fertilisers[2]
* 3m tons per year of organic (poo and pee) fertilisers[2]
Nitrogen-based fertilisers are made from natural gas, and phosphate-based fertilisers from rock. Use of fertilisers grow by 10% every couple of years.
Even if there was no further population growth from now, there's not enough resources on Earth for everyone to have a car, not enough space in cities for every couple to have a house. There's not enough food made from renewable resources.
Are you going to give up your car?
Are you going to give up having a nuclear-family home?
Are you going to give up eating meat?
Can you convince everyone on Earth to do the same?
The goal of every politician is to boost GDP, aka spending, aka consumption. How do you convince politicians they are facing the wrong direction?
Thomas Robert Malthus has not been proven wrong yet. It's only because we've discovered a very large cache of oil and natural gas, allowing the population to continue to expand, for now.
The world is fucked.
QED.
[1] http://www.fertilizerseurope.com/fileadmin/user_upload/publi...
[2] http://www.unep.org/yearbook/2011/pdfs/phosphorus_and_food_p...