Human population size: what’s the problem; why do numbers need to fall? Surely there’s still plenty of space for the existing population, and more?
Our current population growth is the problem. It is driving the rapid depletion of fossil fuel resources with a dramatic increase in associated emissions and consequent climate change; it is accelerating the loss of biodiversity and widespread extinction of species; it is intensifying the growing shortage of fresh water to meet human needs. As a consequence of these changes we face the prospect that agriculture will be soon unable to feed us all, with the poor of the world suffering the most.
Most people don’t know that today’s human numbers are a very recent phenomenon, that as recently as 1930, in our parents’ or grandparents’ youth, world population was barely two billion compared with the nearly seven billion now. People and institutions have simply not adjusted to the sweeping challenge of such explosive growth in human numbers.
The present world population is consuming annually almost one and a half times what the planet can provide on a sustainable basis, according to the WWF and Global Footprint Network. If the current population projections of over 9 billion for 2050 are realised, we shall by then be consuming about double the “sustainable” resources available. This major “overshoot”, means that the collapse of the planet’s ability to sustain us will become almost inevitable.
Won’t population numbers stabilise naturally?
We don’t know when population numbers will peak nor at what level. The ‘medium growth scenario’ of the United Nations Population Division projects around nine billion people by 2050. A largely unreported UN news release [11 March 2009] warned that: “Without further reductions of fertility, the world population could increase by nearly twice as much as currently expected” and reach 11 billion people — with the population still growing rapidly. If nothing is done to encourage population stabilisation and reduction and the projected levels become reality, the consequences are likely to be disastrous.
Population growth has already slowed. Aren’t some industrialised countries now experiencing negative population growth?
We need to separate the overall global picture into its developed and developing world constituent parts.
World – Current ‘medium growth’ predictions by the Population Division of the UN Department of Economic and Social Affairs suggest that the world population will increase from its current level of seven billion to nine billion by 2050. This increase is more than the present populations of India and China combined. Even to maintain populations at their present (unsustainable) levels requires that the fertility rate is no more than replacement level. Allowing for infant mortality, this corresponds to a Total Fertility Rate (TFR) of approximately 2.1 children (live births per woman).
Developed countries – Population decline may be true in parts of Eastern Europe but the population in other parts of Europe and in the United States is rising. Western Europe as a whole has an ecological footprint of 4.51 gHa/capita versus a biocapacity of 3.03 [GFN Ecological Footprint Atlas 2009]. To become sustainable this requires a 33 per cent reduction in consumption.
The UK – The UK is worse off; its ecological footprint is 6.12 versus a biocapacity of 1.58. For the UK to become sustainable, a 75 per cent reduction in consumption is required. The smaller the population, the easier it will be to achieve this whilst maintaining a reasonable standard of living for everyone. The UK’s population has already passed 61million and is projected to reach 71 million by 2033. [UK Office for National Statistics October 2008]. This is the result of births plus net inward migration (immigration less emigration). If overall growth in numbers continues at the current rate, the UK population would reach 100 million before the end of this century. The combination of a projected two thirds increase in numbers and our present level of consumption would be environmentally disastrous. Having reached a record low of 1.63 in 2001 the total fertility rate (TFR) in the UK has subsequently increased, averaging 1.96 children per woman in 2008, the highest level since 1973 [UK Office of National Statistics 27 August 2009].
Developing countries – Fertility remains high in many developing countries. For example, Ethiopia has a TFR of 5.3 and the present (2009) population of 83 million is predicted to increase to over 149 million by 2050. In Afghanistan the TFR is 5.7 with a projected increase in population from 28 million in 2009 to 53 million in 2050 [Population Reference Bureau 2009].
In many developing nations in Africa and the Middle East, population is projected to double in size by 2050. In these countries, large numbers of young people are about to reach childbearing age. Even if these people have fewer children than their parents did, there will be a time lag in the demographic transition during which the number of births still exceeds the number of deaths and the population continues to rise significantly.