On 11 July, the United Nations published its new population estimates and projections. While trumpeting the promise of a lower global peak as “a hopeful sign [for] reduced environmental pressures” in the press release, they don’t mention there are now 43 million more people than they anticipated as recently as 2022. Not such a hopeful sign.
By Jane O’Sullivan
The United Nations released its 2024 revision of world population estimates and projections on 11 July, World Population Day. These statistics are updated every two or three years and published under the title World Population Prospects, which I will abbreviate to WPP hereafter.
Media headlines uncritically announce the report’s key finding of earlier and lower peak in world population as “a hopeful sign” for the global environment. While a 1% reduction in the peak (from 10.4 billion projected in WPP2022 to 10.3 billion in the 2024 revision) is hardly going to avert environmental catastrophes, it would infer a sooner and more rapid population decline thereafter, reducing the period of ecological overshoot. That is, if we can believe this finding.
So, what has happened in the past couple of years to indicate we could be on this lower trajectory? Let’s look at some data.
Firstly, the new revision actually tells us there are 43 million more people alive today than the UN anticipated only two years ago. That’s like adding an extra Poland, Iraq or Afghanistan. This is not mentioned in the UN’s press release. Once again, world population has outstripped the UN’s near-term projection. In 2022, they thought 1 July 2024 would see 8,119 million people, but the 2024 revision tells us it was 8,162 million. Given the 2022 revision expected an increase of 144 million between 1 July 2022 and 1 July 2024, that’s a 30% error!
Figure 1 shows that the UN’s pattern of underestimating future global population continues unabated. If their projections can be that wrong over two or three years, the errors would only magnify the further into the future they project. This chart shows the world population as it was estimated in each revision from 2010 to 2024. The pink line connects each revision’s estimate of the current population, i.e. the mid-2010 population as estimated by WPP2010 connected to the mid-2012 population as estimated by WPP2012, etc. The blue dashed lines show the projection made in each of those revisions. The 2022 revision, while reporting a higher current population than expected in 2019, anticipated a rapid deceleration, narrowing the gap by 2024. Instead, we have seen a larger than ever upward correction. We now exceed the 2010 projection by 226 million people.
This trend is illustrated in the alarming advance of the date on which we passed 8 billion human inhabitants of this precious planet. Table 1 lists the date estimated in each revision of the UN’s medium projection since 2010. Remember all the media attention for 8 Billion Day in November 2022? Now it appears we had missed the event by 8 months!
Table 1: The Day of 8 Billion as projected by successive revisions of the United Nations World Population Prospects (estimated by interpolation).
Commenting on the slightly lower projected peak population, Claire Minoti, an author of the new UN report, said, “it signals that we have come to the end of a process of rapid growth on a global scale that began in the second half of the twentieth century” (launch event video at 12:40 min). Well, we might be able to see light at the end of the tunnel (or have simulated the light by way of modelling assumptions) but it is surely premature to say we have come to the end. The mid-2024 population reported in WPP2024 is 187 million higher than the mid-2022 population reported in WPP2022. That would be a record-breaking 93.4 million per year!
However, the UN’s model downplays this increase by distributing it over more years. In Figure 2, we can see that the higher current population is attributed to a million or so more people than previously thought being added each year over the past 40 years, rather than dramatically more people being added in the past two years. Figure 2 shows the number of people added to the global population annually in each UN revision since WPP2010. The gap between the pink line (WPP2024) and the darkest blue (WPP2022) all the way back to the 1980s accounts for the extra 43 million people. Note that the dramatic dip in 2020 was due to deaths associated with the Covid-19 pandemic, obviously not anticipated in earlier projections. But, whereas the UN expects mortality rates to return to their previous trend quickly, the increment of growth does not, as they expect fertility rates to fall more rapidly.
The UN’s explanation for the lower future peak population is that fertility has fallen lower in some of the biggest countries, particularly China. However, this should translate into fewer people present now, not more. How could the future growth be smaller than previously expected, if the past growth was greater? It’s possible, if the fertility rate is in fact falling faster than anticipated in 2022, but life expectancy has risen even more sharply above expectations. This would keep the death rate lower for now, but increase it in the future as the proportion of elderly people would rise a little faster than previously anticipated. However, given that death rates are still readjusting after the pandemic, it would seem premature to adjust their projection on the assumption of a recent improvement in the underlying trend in longevity.
Figure 3 shows annual numbers of births and deaths, as estimated (solid lines) and projected (dashed lines) in WPP2010 and WPP2024. It shows the 2024 estimates do show slightly fewer deaths over the past 30 years than the 2010 version, but the difference is bigger for births, particularly the size of the baby-boom in the first two decades of this century. Remember Hans Rosling telling us we passed ‘peak child’ (the number of children aged under 5 in the world) in the 1990s? How wrong he was! All those extra children will become parents around 2040, hence the extra hump in births in the 2024 UN projection. But, thereafter, births are expected to drop much more rapidly than anticipated in 2010, as high fertility countries are assumed to reduce fertility faster.
The steep drop in births from around 2018 is more than a little speculative: many high-fertility countries don’t have good birth records, so their actual births can only be estimated some time in the future after a census of people (and by guessing what proportion of people the census missed!). Time after time, we see large revisions in estimates of fertility in these countries a decade after the fact. This is the problem with the UN’s projections: they are projecting forward on the basis of a change they assume has happened very recently, but long before they have good data to prove that it actually happened. When that change is such a dramatic shift from past trends, we have a right to be sceptical.
To its credit, the UN acknowledged that some countries still experience rapid population growth and this is problematic for those countries. In the words of Navid Hanif, assistant secretary general in the UN’s Department of Economic and Social Affairs (which contains the Population Division), “Rapid growth in some countries is likely to magnify the scale of investments and efforts required to eradicate hunger and poverty and malnutrition, and ensure universal access to health care, education and other essential services in countries that are already facing severe economic, social and environmental impediments.” Note that they never admit that the severe impediments experienced in those countries today are largely due to past population growth magnifying their challenges. He advocates “investing in the education of young people, especially girls, and increasing the age at marriage and first child bearing” as well as greater attention to achieving the Sustainable Development Goals. Nowhere is the promotion of smaller families advocated, despite being the most effective approach in the past.
More worrying in this instance is their failure to mention that the world population is bigger than they previously led us to believe. If a hundred million fewer people in 2084 (10.3 instead of 10.4 billion) is hailed as “a hopeful sign” for reduced environmental pressures, why is nothing said about the environmental and social strains of an extra 226 million present now, on top of the expected growth since 2010? There would seem to be a conspiracy of silence.
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