Population ShockLong term population directions, in terms of both size and age composition, drive the destiny of all nations. While for decades we have worried about global overpopulation, it is far more likely that the period 19502050 will be an extraordinary population growth shock, culminating in severe population ageing and then decline. This shock will have four stages aligned with the stages of the life cycle of the baby boomers: childhood, adulthood, old age