Technological innovations will make it possible to sustain still higher levels of population on earth. Like solar energy, electrical cars, etc.
Nodoubt technology will help susytaining more people in lesser space. But the fact remains that more people will be using the limited natural resources. Buildings will be miulti storeyed. You may live underground and make underground roads, build even multi storey towns; devise way to live in Sea by making artificial islands and so on. This has a limit any how. Ultimately there is no substitute for population control.
G. K. Ajmani Tax consultant http://gkajmani-mystraythoughts.blogspot.com/
Population control is important but decision is with people and not on some individual to use force. All that you have mentioned is already begining to happen. In Australia there is are underground complexes where citizens stay to avoid the blistering heat on surface. Technology has no limitations.
We must remember that the problem of population is more pressing in India as USA Russia have 10 times India's land and a fraction of India's population. Europe and japan have controlled population so also China. So the problem is more in SE Asia and mostly in India and Pakistan, Bangladesh. In India the government has already expressed alarm at the population rising to 127 crore. Lets not be smug about it, we are slated to over take China with 1/4 the of the land of China. Hence population is the most urgent problem for India. People talk of world population not facing the fact that the most acute problem is in India.
I agree without an iota of hesitation that population control is the first factor to be taken seriously and the effective measures are to implemented , if necessary with an iron hand making it mandatory to all religions.