Many of our global social and environmental problems are all tied back to the same root problem: There are simply too many of us for the available space and our consumption of resources is pushing the world toward the breaking point. However, the assumption that the global population will continue to grow exponentially consuming ever more resources, may be wrong.
The United Nations predicts that the global population will reach 9.8 billion by 2050 and 11.2 billion by the end of the current century. However, there are several trends that may alter those projections.
First, the global fertility rate is declining. In 1960 the average woman had 4.98 children in her lifetime. Currently, that number is 2.493 and half of the world’s population lives in countries where the fertility rate is sub-replacement level (where there are more deaths than births.) In some countries, the looming population decline has become a serious concern.
A fertility rate of almost 2.5 would still add 25% to the global population per generation, but there is reason to believe that it will continue to decline. First, the trend has been for fertility rates to decline as people become wealthier and better educated and that is happening almost everywhere in the world. Global rates of extreme poverty are less than half of what they were in 1990 and the number of children attending school has more than doubled.
In Western countries, improved public health and access to family planning have had an impact on birth rates, but there are cultural reasons for having fewer children as well. In the developed world, more women than ever before are entering the workforce and pursuing meaningful careers. For some, this means having no children at all, for others it means delaying children until they are older, thus reducing their “childbearing years”.
There is also the somewhat mysterious problem of declining male fertility, which is well documented though poorly understood in Western countries and possibly occurring in other, less well-studied, places in the world as well.
As an aside: The decline in male fertility happens to come at almost the same time as new medical techniques that allow sperm to be manufactured from skin cells. If we were to arrive at a point where an accidental pregnancy was nearly impossible, and pregnancy required a medical procedure, it would certainly have a positive impact on population trends.
So, birth rates in the West will probably continue to decline or at least stay below replacement level and birth rates in less-developed countries will also likely start to level off or decline do to rising incomes, education and better public health.
It is also somewhat likely that people in much of the developing world will become more “Western” both because it is the dominant culture and because of immigration. While high levels of immigration result in a xenophobic backlash in many places, it might be the only way that western countries to sustain long-term economic growth and care for an aging population. The current, high levels of migration might also be the new normal.
Climate change and rising sea levels will force people to move from coastal areas, and some places that are already hot and dry may become uninhabitable. A warming world will also see a decrease in available cropland and inevitable political and economic instability, particularly in places that are not particularly stable now. Mass migration will result in more people living in Northern, more developed countries which in turn will expose those people to the cultural norms which are causing a decrease in fertility rates.
None of this implies that over-population is not a serious concern, it is. We currently do not produce enough food to properly feed the world. That is to say that we do produce enough food for everyone to eat, but not enough food for people to eat a healthy, well-balanced diet with a respectable calorie count. According to the United Nations, in order to continue feeding the world at all, food production will have to double by 2050 in order to keep up with population growth and compensate for land lost to climate change. Also, while the carbon emissions that cause climate change have certainly slowed, they have not begun to decline which means the problems will continue to get worse.
So, overpopulation is definitely a concern, however, the 12,000 year run of exponential growth in human populations may be nearing its end.