Whatever the peak carrying capacity of the Earth, world population might stabilize and remain uncomfortably close to that maximum level once population growth has ceased. Or, more optimistically, world population might decline to a lower, more manageable level for both humans and the environment. Indeed, some population experts and interest groups would welcome such a population implosion. But zero growth or population decline brings its own set of problems. One is that the proportion of the population made up of older people rises dramatically.
Older people consume a disproportionate share of medical and other costly public services.
Labor force shortages also may develop. If population declines rapidly, severe social and economic problems can result. The rate of decline is extremely slow, but many European leaders fear that their falling populations eventually will threaten their economies, their defense systems, and even their national identities. Some European governments have tried various economic incentives to encourage couples to have more children. Some couples receive housing or other benefits if they have children.