The economic and political problems related to population growth are all interconnected of course and shouldn't be considered in unison. As the oil runs out and prices rocket inputs for large-scale mechanised farming will rise which will push up farmers production costs and raise the price of grain; wheat, corn and basic staples will rapidly become unaffordable for the billion or so people on this planet who are already regularly on the brink of starvation.
The same oil is being spewed into the atmosphere in the form of carbon dioxide emissions, thereby rising global temperatures, changing weather patterns and playing havoc with delicately balanced ecosystems. Soil erosion is one of the bigger dangers here leaving less and less arable land for agriculture which in addition to the lowering of water tables in India and China puts further pressure on maximising land use potential. The rapidly rising energy and nutritional needs in both these countries amidst increasing development will inevitably lead to serious stand-offs internationally in the coming years.
Water and oil are the two most important agricultural inputs - the former is already being increasingly privitised leaving smaller farmers cut from the loop. The Green Revolution can only improve yields incrementally and GM crops are the last throw of the dice but it simply cannot make good the increased nutritional needs of an exponential population growth; a 4% rate of increase will double a population in 17 years.
Contrary to popular belief there isn't enough arable land left to feed the projected rise in global population - India and China are already buying up vast tracts of land in Africa to grow grain for their rising populations while they import vast quantities of Brazilian soya bean to use as feedstock for the cattle that provide meat for the shifting dietary demands of their increasingly inflated middle classes. Meanwhile, carbon absorbing Amazonian rainforest is being felled for soya production and biofuels designed to offset projected rising energy prices.
Politically, it's a case of keeping oil prices as low as possible which is why we keep the Saudi tyranny propped up with multi-billion dollar arms contracts and the Iranian theocracy on it's toes but all this policy does in the long run is entrench fossil-fuel dependence on a carbon economy which we should be instead rapidly divesting ourselves from.
Consumers and markets need a stiff jolt to readjust themselves technologically to the prospect of a major shortfall in supply and subsequent price increase - we already saw the beginning of this in 08 when speculators hoarded on oil futures. The next spike is likely to be more enduring, I should think.