Dangerous distraction or elephant in the room? The role of population growth during three decades of increasing carbon emissions

How often have you heard some version of this claim: “population growth is not a problem for climate change, because populations are growing in poor countries whose contributions to global emissions are negligible”? It gets repeated like a mantra, soothing words that banish thought. But what justifies a claim is not the number of times it is repeated, but the evidence supporting it. In a new study, we analyzed carbon emissions and demographic data from the past three decades and found evidence for a very different claim.

by Lucia Tamburino and Philip Cafaro

A dominant narrative in climate change debates asserts that addressing population growth is not relevant for climate mitigation. Population is only growing in the poorest countries, whose contributions to global carbon emissions are negligible, while the largest contributions come from rich countries, where the population no longer grows (or so they claim). Talking about population growth would hence be a dangerous distraction from the “real cause” of climate change: over-consumption in rich countries. It is inferred that addressing excessive consumption among the rich would be sufficient to deal successfully with climate change.

An underlying assumption of this narrative is that the world can be divided neatly into rich and poor. Although common, this view is obsolete and does not reflect today’s reality. As figure 1 shows, when we look at per capita income, the world’s countries form a continuum. Most are neither very poor nor very rich, but somewhere in between.

Figure 1. Life expectancy graphed against income for the world’s countries, 2018. Circles are proportional to population size. Source: Gapminder.

A common and useful categorization among economic analysts is the World Bank’s division of countries into four income groups: high-income, upper-middle income, lower-middle income, and low income. As you can see in Figure 2, the high-income group includes not just Western but also Arab nations (some of which are the richest), Japan, South Korea and several other countries in Asia and Latin America. The upper-middle group includes not only China but also Russia, Mexico and most countries in Latin America, and several countries in Europe and Africa. Africa is usually perceived as a poor continent, but it is actually quite varied, with the majority of the world’s low-income countries, but also many countries in the two middle groups, as well as a few small countries in the high-income group (e.g., Seychelles).

Figure 2. World countries according to the World Bank’s division into four income-based groups as of 2019: low-income (<1035 current US$ average GNI/capita), lower-middle-income (US$ 1036–4045), higher-middle-income (US$ 4046–12,535) and high-income (>US$ 12,535). Source: Tamburino, Cafaro and Bravo, An Analysis of Three Decades of Increasing Carbon Emissions.

So, with a more detailed and up-to-date picture of national income and wealth, how does the common hypothesis about population’s unimportance to carbon emissions hold up? Poorly, it turns out, as we report in a recent study in the journal Sustainability, “An Analysis of Three Decades of Increasing Carbon Emissions: The Weight of the P Factor.”


The evidence

Looking at emissions data, it is true that the low-income group’s contribution to global carbon emissions* is negligible: only 0.6% every year (average over the last three decades; see Table 1). But population isn’t growing only in the poorest countries. It is also growing rapidly in the two middle groups, with the large majority of global population (76%). The argument that “population growth in poor countries is not worrisome, because poor people do not impact carbon emissions significantly,” does not apply to these middle countries: their carbon emissions are significant! Indeed, the upper-middle group currently emits the most carbon of any group: 51% of the global total. Together, the two middle groups contribute more than 64% of global carbon emissions, almost two-thirds of the total. Moreover, the two middle groups are also the groups that currently are increasing their emissions the most, both total and per capita. The upper middle group is indeed the major contributor to global emission increases (see Table 2).

Table 1. Carbon emissions in 2019 by national income group. Source: Tamburino, Cafaro and Bravo, An Analysis of Three Decades of Increasing Carbon Emissions. *Note: data refer to EN.ATM.CO2E.KT, World Bank code for carbon dioxide emissions from the burning of fossil fuels and the manufacture of cement. They include carbon dioxide produced during consumption of solid, liquid, and gas fuels and gas flaring. They do not include carbon emissions due to land use change.

Population is also growing in the high-income group, despite the existence of a few wealthy countries where population is stable or slightly declining, such as Japan. Causes of growth around the world are different: in some cases a mix of demographic momentum (many young people, expected to produce children) and immigration, in other cases a combination of demographic momentum and high fertility. In contrast to the common cliché that only poor people have lots of children, fertility is above the replacement rate not only in the low-income group but also in the majority of lower-middle countries and in around one half of the countries in the upper-middle group. Notably, all African countries in the upper-middle group have high fertility, including three countries with fertility rates >3 and one with a fertility rate >4 children per woman. Surprisingly, there are also some rich countries with fertility above the replacement rate: Kuwait, Israel, Oman, Panama, and Saudi Arabia.

Regardless of the causes, population is still growing in all four income groups, albeit at different rates. During our study period (1992-2019), population increases ranged from 18.5% in the high-income group to 110.2% in the low-income group.

Has this population growth been important in driving recent greenhouse gas emission increases? IPCC Assessment Reports have repeatedly answered “yes,” identifying population growth and economic growth as the two main drivers of climate change. Our study confirmed this finding for the period 1992 to 2019. We compared the contributions of per capita emission changes, population change, and their interaction on total greenhouse gas emission changes (for methods, see the original article). The resulting contributions for all four country groups are shown in Table 2.

Table 2. Contribution of population change, per capita emissions change, and the interaction of the two to carbon dioxide total emission variations from 1992 to 2019. For each country group, contributions are shown in CO2 millions of tons (Mt).

Per capita emissions increase was the most important driver for the rise in CO2 total emissions only in the upper-middle income group, accounting for 63.6% of the total increase. Even for this group, population increase was also a significant factor, accounting for 18.8% of the total increase. Population growth was more important than per capita emissions increase in driving total increase for all the other groups.

The case of the high-income group is especially revealing. These countries represent around 16% of global population and are responsible for 35% of global carbon emissions. They have the highest per capita emissions and need to reduce them. Good news: they have been doing it! In the last three decades, most rich countries reduced their per capita emissions and there has been an average decline in per capita emissions in the high-income group (see Fig. 3, first panel).

Bad news: these countries failed to reduce their total emissions, which increased over our study period, although to a much lesser extent than in the middle groups. This indicates that even if population growth in high-income countries was low compared with other groups, it was sufficient to nullify the effect of reductions in per capita emissions. Not only was population growth responsible for the full increase in total emissions, it was also responsible for the missed decrease that could have happened over these last three decades thanks to reductions in per capita emissions. Figure 3 summarizes variations between 1992 and 2019 in total and per capita carbon emissions and in population, for the four income groups and for the world as a whole.

Figure 3. Carbon emissions in 1992 and 2019, for all four income groups and the world as a whole. The x-axis graphs per capita carbon emissions in tons/capita; the y-axis graphs population in billions of people. Rectangle areas hence represent the total carbon emissions in 1992 (green rectangles) and 2019 (transparent dotted rectangles). Source: Tamburino, Cafaro and Bravo, An Analysis of Three Decades of Increasing Carbon Emissions.


Facing reality

Population growth thus emerges as a major driver of climate change in all country groups, especially the high-income group. More than a dangerous distraction, it seems the elephant in the room that politicians refuse to deal with.

Unfortunately, not only is there a strong reluctance to recognize population growth as one of the drivers of climate change, in many countries there are active efforts in the opposite direction. Low-fertility countries that are moving towards demographic stabilization or decline, instead of embracing these trends, often try to boost their populations through pro-natalist or high immigration policies. This is happening in China, for example, which recently implemented a “three-child” policy, as well as in wealthier nations where demographic stabilization is typically presented as a problem.

Paradoxically, many of these same countries declare their will to reduce carbon emissions, through technological changes or reduced consumption. But reducing per capita impacts and boosting population at the same time is like weaving a canvas by day and unravelling it by night. As wise Penelope knew, such a process will never lead to a finished weaving—or, to leave the metaphor, actually reduce emissions. It indeed risks increasing emissions, which is what happened in the rich countries over the past three decades. Can we afford to let it happen again, during the next three?

Figure 4. Penelope and the Suitors, by John William Waterhouse. Aberdeen City Council Archives, Gallery and Museums Collection. Source: public domain, wiki commons.
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32 thoughts on “Dangerous distraction or elephant in the room? The role of population growth during three decades of increasing carbon emissions

  1. Actually the great, and I’ll add, HUBRIS-FILED MYTH is that overpopulation is in developing nations.
    In net numbers, MOST POPULATION GROWTH happens not in developing nations, but in just three nations: CHINA, THE UNITED STATES AND INDIA, in that order! (Think: What would even a tiny percentage growth rate applied to China’s 1.3 billion people represent in net MILLIONS OF PEOPLE? Though, fortunately, unlike the U.S., China is losing population!

    Hint: When you are the three MOST POPULATED NATIONS, even smaller percentage growth EQUALS HIGHER INCREASE IN NET NUMBERS!

    If you’re fool enough to believe media anymore, their depiction that U.S. “isn’t growing,” (that excluding Biden’s insanity along our southern border). Yet, even they admit we’re growing by .5 percent a year, and that means THE POPULATION OF OURS THE HIGHEST PER-CAPITA CARBON NATION will double in 95 years or less! (With Biden’s absurdity added in and HONEST reporting of our real growth, that will likely happen in more like 50 years.)

    That is why, before in exchange for a $230 million contribution that moved them to say population doesn’t matter, the Sierra Club sold a bumper sticker: THE U.S.: THE WORLD’S MOST OVERPOPULATED NATION!

  2. What is your proposed solution to “Overpopulation”?
    How do you propose to impose a One-Child policy – or Zero-Child policy in all those countries ?
    Do your analyses take into account the _alreafy_accumulated_ emissions by the wealthy colonies-turned-countries as they ravaged the Global South with Imperialist Colonialism burning literally unlimited quantities of wood and coal and oil for centuries ?
    Do you take into account that emissions are often tracked by country of production rather than country of end-use consumption ?
    Do you devote any interest or analysis to the continued and accelerated gratuitous fatuous Bernaysian conspicuous consumption prevalent in The West – most flagrantly in Amerikkka ?
    A case of the silver in the eyes of those “out there” while tolerating the beams in the eyes of us “in here” ?

    We are already in Overshoot
    Incrementalist tweaking will not pull us back from this existential predicament.
    Population tweaking has the longest time constant of all..
    Consumption can be circumstantially slashed by 50% – within months. How do you propose to implement that in the population context ?

    A determined engagement with DrawDown
    DeGrowth De-industrialized petrochemical Mono Crop Agriculture to Regenerative polycrop permaculture
    Doughnut Economics
    are required – just to mitigate the gnarliest edges of the MadMaxxian Dystopia…

    1. Why were the scientists who called for ZPG 50 years ago
      ignored by you and everyone else?

    2. Consumption can be slashed 50% “within months.” You wouldn’t say that if you’d ever advocated for policies to get your fellow citizens to consume less!

      The idea that population policies take a long time to influence overall numbers, that their impact cumulates, is no reason to doubt their importance. The population policies of 50 years ago are influencing our numbers today, for better and for worse. As will today’s policies 50 years down the line. We’re in it for the long haul, right?

      1. It has to be a good sign, that at last you are sounding TOO OPTIMISTIC to some readers!? It means that Reality really is starting to bite, and that has to be a good thing even though “bite” is the right word for this eventuality.

    3. Yes – but Catch 22 – none of your list can happen without first halving the population, or (more likely) without causing the population to halve afterwards as a result, through drought, famine, plague, war, etc. I agree it is wrong to say reducing Population will work (eventually) on its own – but I don’t think anyone here is saying that it will work on its own. Just that it is an inevitable concomitant of a return to sustainable living, at all stages of the return – preliminary, concurrent, and (ferociously) post any forced sudden return to sustainable living caused by Fossil Fuels running out, or by rising seas, or unbearable heat and drought, or all of them.
      Understandably, advocates of Population De-Growth avoid mentioning the other factors needed for a return to Sustainability, because they sound even nastier than artificial population reduction. I think this is a mistake – it is a paradox, and life is full of paradoxes, that humans are more galvanized by fear and horror, than by sugar-coating. The future is still going to be pretty hairy, whatever we do or don’t do, and IMO population biologists should says so – but voluntary population reduction (by various means) can at least lessen the impact of the coming enforced population reduction due to famine etc., which will arrive when Fossil Fuels run out (and has already arrived in South Africa, Sri Lanka, and some other places, but is presently only causing mass migration – to Nations which are going to run out in turn so it is a bit silly).
      Today is World Water Day, and the UN has announced that water is in steep overuse in many if not most Nations, mainly for industry and agriculture. This is an even worse scenario than Fossil Fuels running out – but it has already started, not least in the USA and Europe which use a lot more than many hot arid countries simply because they CAN, or rather COULD in the past.

      1. Drought is an existential horror – especially if you’re not used to it.
        I went through one last year and was desperate. To see everyone around me still wasting water was atrocious. This year we seem to be getting more of the same, but politicians and decision makers are starting to take notice.
        The grass is not growing, the fields are dry, it never rains, and I will have to sell more animals than I had expected.
        It’s a shame that in all of this no one cares about wildlife or the ecosystem. We only worry about water running out when it runs out for *us*, after we’ve taken it from everything else and we still don’t have enough.
        It’s actually hard to advocate for a paradigm shift when people are desperate and will not share.

  3. Those who say poor people’s low emissions mean population doesn’t matter implicitly require that the poor must stay poor as their numbers increase. But, as China, India, Nigeria, Indonesia, Bangladesh and others prove, poor countries try hard to get richer and often succeed. Nigeria–a poor country overall, has a large and growing middle class who are buying cars, bigger houses and air conditioners. NIgerian fertility rates certainly do matter–population projected to double to over 400 million by 2060. Does George Monbiot et al really mean to require that poor people must stay poor so their emissions won’t matter? Do they want rich countries to get poorer? Good luck running for office on that platform. The denial of importance of population is a form of reality denial. In truth, reversing population growth has benefitted women and children and has or will be accomplished (eventually after half a century of population momentum) in over 90 countries. But the hardest half of the world fertility transition remains to be done and won’t happen without intentional effort and funding. And admitting that population matters.

    1. That’s the thing, people like Monbiot and other population-denying virtue signallers don’t have to run for office or even deal with the consequences of what they’re saying. He goes to Wales on holiday and sees there’s too many chicken polluting the water and land, so we must have less chicken. But for some reason he won’t go to Lagos and note that there’s too many people doing the same (we are animals afterall). And if he did, it would be the fault of rich countries anyway, somehow.

    2. Max Kummerow, you write: “Those who say poor people’s low emissions mean population doesn’t matter implicitly require that the poor must stay poor as their numbers increase.”
      I couldn’t agree more.
      Actually we wrote a similar consideration in the original article. Thank you for your evaluable contribution.

  4. Outstanding report; vital information. Anybody in mainstream media understand math?

  5. Information and education do have an impact. When enough individuals have the same information and education we may reach a tipping point. Thank you for Your contribution!

  6. Another measure that ought to be being produced, is a measure of where in the world there might still be places where there is actually room for the population to grow, and survive this century, *at all*.

    As the ‘Year of the Soil’ some years ago, only calculated that there was enough soil in the world for 60 more harvests, and severe weather and erosion both inland and on the coasts can only have accellerated since, and; as the seas rapidly empty of fish at the same time, and are set to become too acid and anoxic to recover before atmospheric CO2 does, the world trade in food is going to collapse in our lifetimes: guaranteed. Meanwhile Bangladesh, Egypt, much of Indo China and China itself, and all other civilisations built on deltas and floodplains (this includes California’s Central Valley), plus Florida, and much of the US east coast, are going to be under water by the end of the century.

    I used to imagine that the USA, Canada, and Russia, might be the only places that might still have room to accommodate any more people at all, once countries all have to revert to feeding themselves on what little soil they have left, but, when I think about how even the US has quite a lot of big cities that need to begin being moved right now, and that Canada seems to be mostly lakes even before all the ice has melted, I’m not so sure. Maybe we do need a third world war, to open up northern Eurasia to massed migration: I don’t think Putin will be wanting to let the displaced billions in: even if Siberia eventually becomes cultivable! 🙁

    Guarantee you that no government will do anything to avert all this, that is, certainly, going to happen: because, you know: Humans.

    1. You speak as if humans were the only species who have any right at all to live on this planet.
      I worry about Siberian wildlife and indigenous people being destroyed right now by resource extraction and logging – not about whether it will be good farmland.

      1. I agree – but I suspect Spamlet was endorsing the firm closure of Russia to foreign exploitation, not advocating it. I don’t understand emojis, but there is one at the end which indicates that the comment is ironic. Meantime, Russia itself is preparing to mine the Arctic, which it has access to as well – but I suppose this is not colonization, strictly speaking, as there is no-one there apart from the Eskimos who are losing their livelihood due to melting ice anyway.
        Real horror is often slightly comic at the same time, and this fact of life emerges clearly from the comment, IMO. There is a kind of “gallows humour” to it which betokens an unusually firm grasp of Reality.

  7. Ah: I forgot about Cuba, which, again some time ago, was said by the World Wildlife Fund to be the first and only country to achieve environmental sustainability. I’m not sure how much will be there by century’s end though.

    I did spend most of my adult life trying to warn about all this, but even in my small doomed nation of the UK, every successive government is still bent on relaxing planning regulations and environmental protections in order to go on ‘developing’ in order to drag in an excess of 300,000 of the world’s young, fertile, and skilled, and wealthy, people every year, forever…

    Oh well. I did try.
    Sorry for the rest of you though. :/

    1. If you are in the UK, BBC Radio 4 has just announced that tonight the programme called The Moral Maze (chaired by Michael Burke) will discuss whether Economic Growth is really a blessing – or on the other hand a curse, a false God. A bit late in the day – but, better late than never. I don’t usually listen to this programme, as such debates have little relevance to extreme Environmentalists like myself – but I might give it a try tonight, though I will probably get impatient with anyone still trying to promote Growth when it is so obviously just cancerous now. I have calmed down a bit since finding other Extremists on youtube – many of them extremly renowned in their field – all telling it like it is and apparently getting some sort of a hearing after decades in the wilderness. They are nearly all American, by the way – but America was the first to go into lethal Overshoot consumption-wise, so it makes sense that it would lead the way into Recovery.

      1. Americans think that history begins with them 🙂
        Human history is littered with examples of societies that went into overshoot… it’s only that we refuse to acknowledge them as such, but there are innumerable examples.

  8. UN/IPCC “Net Zero Emissions” is the global fairy story of the 21st century, visibly contradictory, as just one glance at the post-1990 world emissions chart tells you. But the economists and the religionists love it equally, because it means they can ignore the population onslaught, and continue unrestrained the global war on the environment. Powerful nations love it too.

    Instead of demolishing the UN conceit, world science has 95% climbed on their bandwagon, grossly failing us. Evidence-based critiques like this are vanishingly rare. So, thanks.

  9. Fully agree with the article, but perhaps carbon emissions of the poor have been underestimated. Do the carbon emission include those due to removing a forest and replacing it with agriculture or grazing?

    1. You’re right: carbon emissions of poor countries have been underestimated, exactly because we used data that do not include emissions due to land use change (see Caption of Table 1). Actually, population growth is probably even more important than what we found. In the original article, there is an entire paragraph in the Discussion where we say exactly this. Good point.

      1. Have you ever read the studies according to which the European “discovery” of the Americas killed so many people there it actually changed the climate of the Earth?
        I keep bringing this up, I want to find someone with scientific background who will look at it in a demographic context. If true, it shows it’s not just about “capitalism” or the “overconsuming West”.

  10. A comment just popped into my mailbox on an article written a year ago (April 12th 2022). This is providential, because the article in question, expertly criticising Working Group III’s contribution to the IPCC’s Sixth Assessment Report on Climate Change, kicks off with a huge graph from the IPCC showing “Net anthropogenic greenhouse gas emissions per capita and for total population, per region (2019). The height of each rectangle shows per-capita emissions, the width shows the population of the region, so that the area of the rectangles refers to the total emissions for each region.”
    All well and good – except that the AREA of each rectangle is not calculated, and indeed not possible to calculate using this graph, and thus the only thing that strikes the average, non maths genius, reader is the PER CAPITA height of all the usual suspects. Yet the tallest bar, North America, is also one of the narrowest – whilst some much lower bars are very wide indeed, e.g. Eastern Asia. .
    Guess what – the larger a Nation’s population the smaller the result when you divide quantity of emissions by the number of humans. Simple? – yes, but also very easy to misuse. In fact, several accountants of my acquaintance mutter constantly that governments and business are sly and cunning about when they use Per Capita and when they don’t. They use Per Capita when it suits their agenda, and not when it doesn’t.
    The current article here makes an effort (at Figure 3) to show TOTAL emissions – albeit on a Per Capita graph – by shading the area of total emissions green – but only on an income groups basis, which is not very revealing as there are many billionaires in “poor” countries these days. Also, some “rich” countries contain such huge pockets of stark poverty these days that they should not be called “rich” at all.
    But anyway, my point is, it is playing straight into the hands of the expert Necromancers handling “data” and “figures” in a creative way, to use Per Capita stats at all, when it comes to Emissions. Instead, look for where the necromancers refuse to use Per Capita stats – and use them there instead.
    As the populations of North America and Europe and Australia swell through Mass Migration, watch their Per Capita emissions go down (provided they are not emitting more total emissions). Is this why their governments have no wish to stop overpopulation? – because it brings down the Per Capita emissions? And at the same time a growing population conveniently swells other stats not calculated on Per Capita basis – stats which look better swollen than shrunken (in the eyes of Gluttons).
    One stat that, like Emissions, does not look better swollen than shrunken, is Groundwater usage. Here again, presenting only Per Capita usage could mask the real life horror of increasing use of a finite resource that is even more precious than Fossil Fuels. Because the more people there are, the lower the Per Capita extraction figure will be. However, no-one is charting Groundwater use either in total or per capita – why would they? It is beyond scary, and completely anti Growth of anything, including Population. It also smashes straight into the heart of Global Business as it is NOW, without any more Growth – i.e. intensive agriculture and mass production industry. I did find a great website charting global Groundwater availability and usage, but it is not up to date.

  11. Edith Crower, Russia has been engaged in internal colonialism for centuries now. The fact that the people you displace and exploit are technically within your borders, and not outside of them, doesn’t change the nature of exploitation. Same for most large countries, unfortunately.

    1. Humans exploit other humans – and the exploiters are often “poor”. Desperadoes of any nationality are particularly ruthless when it comes to stamping on any environmental concerns that stand in their way (i.e. all of them – climate change, biodiversity, pollution, water shortage, etc. etc. etc.).
      Russia is no exception to the laws of human nature – but it does stand out for its low population, however that came about, and its even lower population density which came about due to its geographical size.
      As a result, it also stands out for its complete self-sufficiency, relative to any other Nation in the world. It is not using any of these (overlapping) assets wisely of course – but no other Nation would be any better, that much is obvious.
      Certainly the “West” must grab Russia if it is to survive – and we see this now in action, with a stout defence by Russia, but in the end, Russians are outnumbered by the rest of the world. It is not just the West – Asia and Africa and South America need the Remnants of Nature’s bounty to maintain a “civilized” lifestyle even with much-reduced populations – and those Remnants are to be found in very few places indeed.

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