Urban farming is very much the way of “sustainable” food supply, even in the face of sharply rising population numbers, both through extended life spans and the natural exponential increase of humanity over time. The time is coming when only the most productive means of food production will even have space to operate on Spaceship Earth.
To make this possible, the collection and extraction of energy shall have to be optimized to a much higher level than now is considered acceptable.
We have the technological capacity, and we are rapidly developing the economic incentive. When shall the will to institute this new technology be exerted, and the methods more widely adopted?
And yes, people, it is going to require carbon dioxide to make this system work. Lots of it. As much as we can produce.
When the unbreakable law of economics mandates it.
Until then we will continue as we have been, growing our food on open ground, with huge surpluses.
Many of those surpluses are exported, many are burnt to heat our homes and fuel our cars and are also used to fan political flames. Some are simply plowed back into the soil.