One of the many ways in which a concern about population is shutdown is through the curious application of declining-growth-rate projections. Even before this spurious argument is applied, the glaring assumption is that current population is not a problem, is sustainable, and what’s a ‘few’ more (read billions!) before it all, ‘naturally’, levels off and even declines?
Even the most cursory examination of state-of-the-environment data (e.g. see Home section, ‘State of the Environment’), would show the parlous state of the natural world in the face of the current burgeoning population and consumption, as would acquaintance with ecofootprint data, which I have shown repeatedly in T10 to demonstrate overshoot and ecological deficit. Here it is – again:
Try, also, telling the 68% of vertebrates eliminated from the globe since we ‘overshot’ bio-capacity in 1970 that it is ‘not a problem’!
In 1970 the earth’s biocapacity was about 10 billion global hectares and the population approximately 3.7 billion2, and the volume of consumption was approximately equal to global biocapacity. (Remember that this ‘capacity’ takes no account of the requirements of other species; it is calculated as 100% for human consumption). So, without allowing for other creatures, in 1970 and at 1970’s levels of consumption and numbers (3.7 billion) we were at capacity. Therefore, the more than four billion added from this date has all been beyond capacity and deleterious to our and the world’s health. If this is converted to a calendar year, then we reached capacity in 2021 on July 29th3 and every day after that required depleting the planet’s natural capital stock, as well as finite mineral and fossil-fuel reserves.
To make matters worse, this overblown population has not stopped, but is powering onwards at around +80 million/year4. How long will this go on?
At one level, this is impossible to answer. Coalescing, cascading effects, threshold levels, technology, cultural shifts, impaired functioning of ecosystems, complex feedback loops and changing demographics, etc., amount to too many variables for a definitive answer, but nonetheless, projections have been attempted. Perhaps the most rigorous of these is that by the United Nations’ Department of Economic and Social Affairs (UNDESA) which is tasked with determining current and projected population to help set, and monitor progress, on matters such as Millenium Development Goals. Their 2012 revision4 – WPP2012_HIGHLIGHTS.pdf (un.org) – indicated:
Figure 1 presents four projections and that which was adopted was the ‘Medium’ variant (blue) “which assumes a decline of fertility for countries where large families are still prevalent, as well as a slight increase of fertility in several countries with fewer than two children per woman on average”.
Fertility was seen as the key variable for the future with a world decline from 1950 to approximately 2000, then a slower decline to around two children per woman by 2100.
Death rate (as reflected by life expectancy) was seen as less impactful, with a considerable decline between 1950 and 2020, and then only a slight decline in rate thereafter.
In total, their key finding was:
- “Key Findings 1. In July 2013, the world population will reach 7.2 billion, 648 million more than in 2005 or an average gain of 81 million persons annually. Even assuming that fertility levels will continue to decline, the world population is still expected to reach 9.6 billion in 2050 and 10.9 billion in 2100, according to the medium-variant projection”.
This figure is considerably higher than the often bandied about – 9 billion – which has been seen as the ceiling of world population for some time now. The UN DESA says this was an erroneous estimate as it was based on incorrect, low, measurement of fertility rates in a number of countries and overestimation of declining fertility rates in others5.
The momentum of massive population growth since 1800, plus a world religion and belief system devoted to it, means that the overloading of the earth will continue apace for at least another 50-80 years or more, and beyond that it is impossible to know what will happen. Despite this, one thing is certain: the longer we delay in addressing the problem, the narrower and harder our choices in the future will be.
Returning to biocapacity, examination of graph 11.1, above, indicates a world fertility rate of roughly 2.5 now, dropping to a projected 2.0 at around the end of the century. If this happens then the population curve will begin to flatten in the next century (it’s not a straight 1:1 relationship with fertility equalling replacement level, as it depends on how many woman are in the child-bearing age groups), but we will still be in massive ‘overshoot’. How do we return to something more sustainable, and what is that level? Actions for reducing future population will be dealt with later in Section 5, but we can suggest a biocapacity target next, in webpage 5.7.
1 WWF. 2020. Living Planet Report 2020 – bending the curve of biodiversity loss. WWF, Gland, Switzerland.
2 Worldometer. 2021. World Population By Year. https://www.worldometers.info/world-population/world-population-by-year/
3 Earth Overshoot Day. 2021. https://www.overshootday.org/
4 United Nations Department of Economic and Social Affairs. 2013. World Population Prospects: The 2012 Revision. United Nations, New York, USA.
