This video discusses how cities may change in the face of uncertain future food, energy and water supplies. It is presented by Christopher Barnatt, Associate Professor of Computing & Future Studies in Notingham University Business School.
With smart planning surface farming and around the cities could provide for the nutrition needed by the residents of the cities and surrounding areas.
A number of countries in asia are already implementing vertical farming. It hasn't reached critical mass yet whereby most of cities food is acquired through city farming and greenhouses.
Right now skyscapers in most big cities only collect rent. At least by having hydroponics or vertical greenhouses it would make skyscrapers productive and would be an integral part of city living, by providing a food source close to the cities residents.
Source www.explainingthefuture.com.