Do the ‘population doesn’t matter’ arguments stand up to their own evidence?

At the Green Party autumn conference, I attended an early morning panel discussion on population. I wrote about this in a recent blog post, describing the debate between a representative from Population Matters and Sebastian Power from the Green Party. I also mentioned that Sebastian offered during the debate to send references for his claims to anyone who was interested in what he said.

Now that he has sent these around, I wanted to write a third (and hopefully final) blog entry on the population debate. Having followed up his references, I felt I had to write this because so many people in the conference audience and more widely will have heard his arguments and heard his claim that he based them on solid, scientific references. He also made the same arguments in an article for the internal magazine, Green World, and I have heard the same arguments from several other party members.

This post is all the more important now that some members have submitted a proposal to delete the Green Party’s entire policy chapter on population at the spring 2014 conference.

I realise that in writing this blog entry it could seem like an extended personal attack, but I really don’t intend it that way. I want fellow Green Party members to find points of consensus on which we can mobilise to elect Green politicians and engage in other Green political action. I don’t want to dig trenches and see party politics as a protracted internal war of attrition. But in light of the above I feel it is important to publicly air a critical examination of these arguments, and to examine how our own policy on population stands up in relation to the academic literature Sebastian has circulated.

The headlines, for those short of time

For the impatient, the key points that one should draw from the references he circulated are:

  • population is relevant, and stabilising the global population sooner rather than later through policies like family planning and access to contraception could deliver up to one fifth of the greenhouse gas reductions we require
  • there is no simple solution to feeding nine or ten billion people while addressing environmental problems, it will require revolutionary changes in production and consumption around the world, not just in the West
  • the academic and journalist literature mentioned below often point towards exactly the principles and policies found in the Green Party’s population policy chapter

The references

Here is what Sebastian sent us following the debate at conference:

According to a paper in the scientific journal Nature, global population will peak this century at around 10 billion1. UN Department of Economic and Social Affairs reckons “even if zero population growth were achieved, that would barely touch the climate problem”2. According to another paper in Nature we will also be able to sustain 10 billion so long as we change our consumption habits in the West.3Danny Dorling4, Ian Angus and Simon Butler5 and literally hundreds of other authors of peer reviewed journal articles also come to the same conclusion.6

Kuylenstierna believes we need ‘productivity increase, changes in trade and market regimes, climate change adaptation and an increased focus on land and water management issues’7 but does not believe population growth is the fundamental problem, especially considering it will, according to the peer reviewed literature, plateau at around 10 billion.

Monbiot has done a lot of research on population/consumption and I generally agree with his opinion on the matter. Worth reading what he has to say about it.8

1 Wolfgang Lutz, Warren Sanderson and Sergei Scherbov, 20th January 2008. The coming acceleration of global population ageing. Nature. doi:10.1038/nature06516

2 UN Department of Economic and Social Affairs, 2005. World Population Prospects.

3 Foley, J. 2011. Solutions for a cultivated planet. Nature 478, pp 337–342

4 Population 10 Billion by Danny Dorling



7 Kuylenstierna, J. 2008. Feeding the future world: securing enough food for 10 billion people. Water for Food 

I’d like to cover each in turn, then make a general critique of Sebastian’s portrayal of his research, and then turn to the Green Party’s policy.

1 – Global population will peak this century at around 10 billion

I don’t have any argument with this suggestion, which seems uncontroversial. Population growth is already slowing, and ten billion is within the range that most experts seem to agree on, as you’ll see in some the articles I review below. I will note, though, that the difference between a population of nine, ten or twelve billion (the normal range given by the UN) is very substantial.

2 – Even if zero population growth were achieved, that would barely touch the climate problem

This argument sounds like a strong reason to ignore population.

Sebastian’s reference didn’t actually contain the quote he gave – that zero population growth would barely touch the climate problem. The report he linked to wasn’t the ‘World Population Prospects’ report he mentions, nor could I find evidence that a 2005 revision of this report was ever published, and the versions of that report I could find make no mention of this debate. But the exact quote can be found in the State of the World Population 2011 report by the United Nations Population Fund. Sebastian is critical of this branch of the UN, pointing out to me in over email that they have been criticised for “dubious assumptions” in some of their population projections. Anyway, as this is the only place I could find that quote I presume it’s his reference, so here’s what it says.

The report states that consumption is the key, but not only, problem. Before it concludes that “zero population growth… would barely touch the climate problem”, the authors cite a paper published in the Proceedings of the National Academy of Sciences. That paper suggested that “slowing population growth could provide 16 per cent to 19 per cent of the emissions reductions suggested to be necessary by 2050 to avoid dangerous climate change”.

So by “barely touch” they mean “only deliver up to one fifth”. It does not say that stabilising population will have no impact on climate change, it says the opposite.

Bear in mind that 16 to 19 per cent of emissions reductions is probably greater than the entire impact of domestic energy efficiency programmes.

3 – We will also be able to sustain 10 billion so long as we change our consumption habits in the West

The paper he refers to sets out a number of challenges to overcome in feeding ten billion people. One of its main sources for problems is some work by the Stockholm Environment Institute, which covers a range of major challenges and quantifies the changes we need to make. I touched on this SEI paper in my second of three blog posts on the subject.

Reading both papers gives you some idea of the challenges we face, and the depth and breadth of changes required to meet them. The authors of the paper suggest that we could “double food production while greatly reducing the environmental impacts of agriculture” by “halting agricultural expansion, closing ‘yield gaps’ on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste”.

I will raise two points on this paper.

First, this is not the same as saying we just need to “change our consumption habits in the West”. This paper lays out massive changes to the entire agricultural system across the globe, with targeted measures in every country depending on particular local issues. In the tropics, they say farmers should stop clearing forests. In many parts of Africa, Latin America and Eastern Europe, they advocate better deployment of existing crop varieties with improved management of water and nutrients. In developing countries, they suggest better storage and transport to stop 40% of post-harvest food being wasted, and in developed countries they pin a similar proportion of wastage on retailers and consumers.

Second, the changes the authors cover, taken as a whole, pose an immense challenge. They describe it as a “revolutionary approach”. I argued in my first population blog post that we shouldn’t underestimate the difficulty of achieving such big change. Given the importance of grappling with these issues, we can’t afford to hide in utopian politics.

Let me turn to another example for a moment. It may be theoretically possible, as the Committee on Climate Change suggest, for us to meet climate change targets while aviation expands by 60 per cent. But that would require us to reduce emissions elsewhere by 90 per cent. Given the gravity of the situation and the difficulty of achieving those 90 per cent cuts, not to mention that we have reasons to think the Committee is unduly optimistic, most Greens argue that it isn’t worth the risk and we should halt the expansion of aviation.

I would argue that the same could be said of population. Even if it were theoretically possible to tackle climate change, resource depletion, deforestation, biodiversity loss, the disruption of the nitrogen and phosphorus cycles, and all other environmental problems without aiming to stabilise population sooner rather than later, not trying to do so would make our task much harder. If socially just means of stabilising population sooner rather than later can deliver up to 19 per cent of emissions reductions, they would make our chances of sustainably feeding the world’s population a good deal more realistic.

4 and 5 – The books

I’ve not read these books, and buying them or getting them from the library seemed over the top in writing this blog entry. If what they say particularly contradicts the academic papers I’ve read in writing this blog, I’d be interested to know why.

6 – the hundreds of other peer-reviewed articles

I’m not going to read hundreds more articles on the strength of a recommendation from somebody who has misrepresented the work I have reviewed so far. I just don’t have the time. So I read the first article on that page that I could access without payment just to test the waters, and it made for very interesting reading.

The paper in Science magazine, ‘Food Security: the challenge of feeding 9 billion people‘, looks at how we can reconcile this with environmental sustainability. Its content is very similar to the paper in section 3 of this blog.

It looks at closing the yield gaps that often occur

“because of technical constraints that prevent local food producers from increasing productivity or for economic reasons arising from market conditions. For example, farmers may not have access to the technical knowledge and skills required to increase production, the finances required to invest in higher production (e.g., irrigation, fertilizer, machinery, crop-protection products, and soil-conservation measures), or the crop and livestock varieties that maximize yields”.

The authors caution that “we do not yet have good enough metrics of sustainability, a major problem when evaluating alternative strategies and negotiating trade-offs”, suggesting they are far from confident that they have reconciled the problems “at the interface of science, engineering, and economics that urgently need more attention”.

They cover the sovereign wealth funds that are buying up land, funds by the way that are based in countries as diverse as Norway, Libya and China. In my previous blog post I discussed Sebastian’s suggestion that rich, white men in the West are principally to blame for our environmental problems because they consume too much. But those aren’t all countries run by rich, white men in the West.

The authors also mention the pressures arising from the “rapidly increasing demand for meat and dairy products… largely attributable to the increased wealth of consumers everywhere and most recently in countries such as China and India”. Again, are these all the rich, white men we are told to blame?

But it is their conclusion that is particularly important for everyone interested in this debate to reflect on (emphasis added):

There is no simple solution to sustainably feeding 9 billion people, especially as many become increasingly better off and converge on rich-country consumption patterns… Together, these challenges amount to a perfect storm. Navigating the storm will require a revolution in the social and natural sciences concerned with food production”.

It bears repeating: the academic literature should not give us hope that “we will also be able to sustain 10 billion so long as we change our consumption habits in the West”.

7 – Population isn’t the fundamental problem

The chapter in the ‘Water for food‘ booklet that Sebastian refers to is written by Johan Kuylenstierna, the Chief Technical Advisor for UN Water. So far as I can tell, this wasn’t peer reviewed. Sebastian suggested that Kuylenstierna does not think population is “a fundamental problem”.

But this is clearly misleading.

The author repeatedly states that population growth is one of the underlying factors, is a challenge, and cannot be ignored as part of the complex issue. If we understand “fundamental problem” to imply “impossible to solve”, then at best Kuylenstierna leaves us with other factors that might allow us to supply enough water to feed the world even with the projected population growth. But he offers no evidence that we can do this, he only expresses his hope that it might be possible.

He clearly outlines why population growth is a relevant factor that cannot be ignored, one that limits our options, just as ruling out onshore wind farms would limit our ability to generate electricity in a more ecologically sustainable way. 

Here are some quotes that set up the context:

Keeping pace with population growth remains a challenge in many regions

[The current situation] shows the complexity of current problems – how difficult it is to understand what the main drivers are and how they interact

With a population approaching 6.5 billion and still increasing by 90 million each year, the degree of freedom to act is becoming limited, and minor changes can trigger substantive effects.

He states that it is “a responsibility [of] anyone working with global development issues not to believe [that] the same technologies and methods we have developed over the past two centuries will, with some refinements, be enough to cope with future challenges”. It’s one thing to hope this, but he states quite baldly that “improvements have lately not managed to keep pace with the total population growth”. Faith versus fact.

The author also states that our understanding of the impact of climate change on water resources for growing food is limited. He hopes that “if we strengthen capacity to deal with current [climactic] variability, through improved water management and investments in infrastructure and adaptive physical planning, humanity will clearly be better prepared to deal with climate change by 2050.” Of course we will be better prepared, but do we know how to make these changes to an extent that will enable us to feed ten billion in a world that warms by 2°C or 4°C? He doesn’t say.

In an honest paper that repeatedly stresses the complexity of feeding the global population, Kuylenstierna also pays no attention to whether the population could be stabilised sooner rather than later. If, as reference 2 suggests, this could deliver 16 to 19 per cent of the global emissions reductions we require in a socially just way, it’s a critical oversight on the part of Kuylenstierna.

8 – What does George Monbiot say?

Monbiot has written some very strong articles on this subject, and most of Sebastian’s references are also found in Monbiot’s articles from the past four years or so.  Monbiot’s main theme is attacking “post-reproductive wealthy white men” whose “sole purpose” is to raise population as an issue in order to distract from their own impacts, best argued in this article from September 2009.

However, he doesn’t argue the same case that has been made by Sebastian and others in recent party debates. In fact, Monbiot’s argument pretty much reflects the Green Party’s position, as I’ll show in the last section of this blog.

In that article from 2009, he proposes that we adapt “the old formula taught to all students of development – that total impact equals population times affluence times technology (I=PAT)”. It is wrong, he says, it should be “I=CAT: consumers times affluence times technology” because “many of the world’s people use so little that they wouldn’t figure in this equation [and] are the ones who have most children”. But this is really just an adjustment of who we count in “population”, not a rejection that population is relevant at all.

As he wrote in April 2013, “I agreed that population is an element of the problem, but argued that consumption is rising much faster and – unlike the growth in the number of people – is showing no signs of levelling off”.

Following his reading of the report that I covered in section 2, he wrote, in October 2011 that the relatively smaller contribution made to climate change and other environmental problems by population stabilisation should make it the junior partner in this debate. His concern is with the wealthy and powerful trying to use population as a distraction to avoid policies that address their own impacts, not with it being raised at all. In his 2011 article he saysthis should not prevent us from strongly supporting the policies which will cause population to peak sooner rather than later. Sex education, the report shows, is crucial, so is access to contraception and the recognition of women’s rights and improvement in their social status. All these have been important factors in the demographic transition the world has seen so far.”

In his 2013 article, he points out that wealthy people commonly emphasise things like “recycling and population” in order “not to see the clash between protecting the environment and rising consumption”. They are probably raising a red herrings – a kind of informal fallacy where one attempts to change the topic of debate to save one’s skin. It can also be less conscious. I have often come across the sort of people who mention recycling and their veg box while leaning on their 4×4 about to go on their third foreign holiday of the year. Their hypocrisy (or inconsistency) doesn’t make veg boxes or recycling wrong or pointless. In the same vein, hypocrites emphasising recycling and population doesn’t logically make those issues wrong or irrelevant.

A more general comment on “peer-reviewed science”

Credit for this point really goes to Andy Chyba from Bridgend Green Party. Sebastian made much of his references to peer reviewed science during the debate at the Green Party conference. In a later email he tried to suggest an equivalence between his reading of the literature and the Intergovernmental Panel on Climate Change‘s work on climate science. This shows a confusion on two points.

First, the IPCC’s fifth assessment report involved more than 250 scientists from 39 countries examining more than 9,000 scientific papers and nearly 55,000 comments on their work. It was an immense and unparalleled exercise in peer review, and to compare the level of consensus on population to that of the IPCC undermines the latter’s significance.

Second, there is a difference between empirical science based on observational data, and the academic work Sebastian refers to about possible future scenarios based on loaded and imprecise assumptions. Yes, the work has been peer-reviewed so we can assume it is of a high quality and credible. But it doesn’t make the work correct, nor as certain as science based on the observation of phenomena confirmed by subsequent tests. It also doesn’t mean all of these revolutionary changes are feasible or likely.

I have had work published in a peer-reviewed journal on BedZED, the eco village where we found that the usual strategies to reduce consumption still left working class tenants with unsustainable carbon and ecological footprints (‘Towards sustainable residential communities; the Beddington Zero energy development (BedZed) and beyond.’ Environment and Urbanisation 21: 527 – 544, 2009). I mentioned this in my first blog to argue that achieving sustainability is much more difficult than many make out. I would like to think it is credible work of a high quality, but it is in no way comparable to that of the IPCC, nor is it ‘scientific’ and so beyond reproach.

I would hope we would make much more use of peer reviewed academic literature, along with other means of getting at the truth such as randomised controlled trials of policies. But we shouldn’t confuse respect for scientific evidence with scientism – the attempt to displace political ideologies by slavishly following current scientific research programmes. It might be great science, but it might ask all the wrong questions, or be chasing the wrong objectives. Ironically, it seems that Sebastian got the science dead wrong in order to arrive at the answers he wants to suit his ideological position.

What does the Green Party’s population policy say?

I wanted to cover the population issue in so much detail because some members of the party want to change or delete the population chapter in our Policies for a Sustainable Society.

So what does it actually say, and how does it stand up in relation to these various academic papers?

Our population policy:

  • is based “on the principles of ecological sustainability, equity and justice”
  • sets out some of the general reasons why it should be “explicitly considered”
  • protects individual liberty, for example it “holds that the number of children people have should be a matter of free choice”
  • reaffirms our “liberal migration policy” that should achieve “greater global justice and equality” and rules out restricting migration on grounds of “social, economic and environmental pressures” that might arise
  • notes that the UK’s consumption is unsustainable, which is also detrimental to the global south, and reaffirms our commitment to deal with our own problems and support poorer countries to develop their own economies

The chapter therefore sets population up as the junior partner to other related issues of ecology and social justice. This is exactly what you would do if you were basing your policy on the academic papers I have reviewed in this blog, and on the views of journalists like George Monbiot.

The chapter then proposes twelve long, medium and short term objectives (which should be read in light of the hundreds of policies in other areas that address the UK’s over-consumption). These cover the familiar points about ensuring access to family planning services and sex education. These objectives also, again, affirm the importance of tackling consumption in the developed world, affirm the need for socially just migration policy, and rule out setting population targets.

The party’s sole objective is definitely not to distract from consumption but rather, as Monbiot advocates, to strongly support policies which will cause population to peak sooner rather than later in a humane, liberal and socially just way. I would hope that any Green Party member interested in the evidence would support our policy.

Endnote – many thanks to my friend Ed Jones for his help reviewing this post, helping me to write more clearly and be more rigorous in my research, as he has done a number of other times.


  1. corinja said:

    Another really important and well-argued blog post. As a follow up, and I’m not suggesting this is something you would want to do, Tom, but perhaps others could think about, I would like to see some analysis of the ideological or psychological tendency behind the wish to argue against our rational, sensible, ecologically minded population policy.

    I’d speculate it comes from two places.

    The first would be a determination to not be seen to be on the same side in any way as some of the notoriously right-wing anti-immigration/pro-population control groups. I’d guess the feeling is that any hint of agreeing on this issue with those groups fatally undermines the Green claim to be a muscularly Leftwing party. ‘Real’ leftists don’t blame anything other than capital for the social and ecological crisis, so population must be a red herring.

    Secondly, I think people want to avoid any accusation of misanthropism. The claim would be that arguing for a reduced or stable population denies the fundamental greatness of human people, and we don’t hate people so surely we can’t want to restrict their numbers. This, I think, is a more interesting philosophical position, which can’t be glibly dismissed, but I’d argue something along the lines of a preference for a smaller population of very much equally well-provided for humans, sustainably integrated into local and global eco-systems, over a larger much less well-provided for population similarly integrated.

    Of course, I am only speculating. Perhaps the concern does not arise from either a need to fit the party into a particular historical tradition, or from a lack of ecological orientation. Perhaps those arguing against any attention being paid to population really do just want the best for people and planet and have decided, having weighed up the pros and cons, including the evidence you have analysed above, and come to this conclusion. I hope that’s the case, because then the door is open to mutually agreeable debate from flexible positions.

    3rd November 2013
    • Tom Chance said:

      Hi Corin,

      I think those are really good points, though as I said I am hoping it’s my last blog post on the subject so I’m going to decline your offer!

      It doesn’t help that Population Matters speakers apparently turn to anti-migrant rhetoric, and that there are many unsavoury types who tak about population.

      I’m not actually interesting in focussing on population as a big issue, but I got drew into this because it seems to be of a piece with increasingly vocal and effective attempts to excise the Green Party of aspects of its philosophy and policy which distinguish it from more traditional left wing parties.

      3rd November 2013
  2. Chris said:


    Can you explain why you say, “It doesn’t help that Population Matters speakers apparently turn to anti-migrant rhetoric”. I’m a pretty active member of Population Matters and am at a loss to know why you say this. Can you provide a quotation of the kind of thing you have in mind?

    4th November 2013
    • Tom Chance said:

      Chris, my only direct experience of Population Matters is at that conference panel. But it’s something I’ve been told anecdotally by people I trust – I should have qualified it to say “some speakers sometimes turn…”.

      4th November 2013
  3. Chris said:

    Tom, it is very much out of the character of your blog to rely on a non-specific, vague second hand report, even from someone who you trust. I have never encountered any PM speaker saying anything that could justify that comment. It is very much out of character of the organisation and would receive very swift censure internally if it was brought to the attention of the board that anyone speaking on behalf of it, had expresses an anti-immigrant sentiment. There is certainly concern at current high level of immigration into the UK, but the importance of the distinction between being concerned at this, and being anti-immigrant at an individual or group level is clear to any decent person, and always made very clear. There are many people who want to believe this kind of thing, and it greatly concerns me that you should be spreading false rumour.

    4th November 2013
  4. legjoints said:

    There seems to be a misprint in the State of the World Population Report you refer to in its quotation from the paper “Global demographic trends and future carbon emissions”. If you look up the original paper on PNAS they say in the abstract “we show that slowing population growth could provide 16–29% of the emissions reductions suggested to be necessary by 2050 to avoid dangerous climate change”, whereas you and the UN quote this as between 16 and 19%.

    However, I think what’s more important is what they mean by “slowing population growth”. Do they mean that because population growth is slowing, which it is, then this will result in lower emissions than would be the case if population were to continue growing at its current rate? Or do they mean that by taking action to slow population growth we could cut emissions by the stated amount?

    From the title of the paper and the rest of the abstract (the full paper is behind a pay wall) it seems clear to me that the first reading is correct since they’re addressing how emissions scenarios have not properly taken current demographic trends into account – and they do seem to be talking about a number of demographic trends, not just numbers of people but also the effects of an aging and increasingly urbanized population.

    It would be worth reading the full paper, but since (as mentioned in the UN report) the poorest 50% of the world’s population account for only 7% of its emissions it’s hard to see how reductions in their birth rates could account for much of that 16-29% emissions reduction. It’s in the rich countries where the birth rate is below replacement level and in the poorest countries where the birth rate is above replacement level, so we’re seeing a reduction in population coupled with an aging of the rich world, and that I’d guess is what’s responsible for most of that 16-29%.

    So if you want to bring about reductions in emissions via reductions in birth rates you’d need to focus on the places producing those emissions and persuade women in wealthy developed countries to have even fewer children than they’re currently having, which on average is well below replacement level of 2.1 per woman.

    6th November 2013
    • Tom Chance said:

      Hello there,

      Thanks for the correction. Actually the full paper can be read free of charge here:

      The authors look at the impact of the global population growing in the low, medium and high growth scenarios published by the UN, and consider these population pathways as exogenous to their emissions model. But they do discuss, right at the end, that policy levers such as economic development and access to family planning could help bring about the lower population pathway of just over 7 billion people in 2050 and 5.5 billion in 2100, while the lack of such policies increases the likelihood of the medium or high scenarios.

      So your guess is wrong.

      This gets to your point about where the emissions arise today. That isn’t in question. The relevant question is where emissions will arise, cumulatively, between now and 2050, or 2100. Do you imagine the per-capita income of every country will remain unchanged over the next forty to ninety years? Just look at these annual growth rates:

      In fact, the authors mention two example countries where these population-stabilisation policies could have a big impact – the United States and China.

      As the papers on food I reviewed in my original post point out, much of the rising demand for food is coming from the rapidly developing economies. If liberal, socially just policies to stabilise the population in those countries sooner rather than later can be implemented while helping to increase their per-capita income as per the contraction and convergence model, that will – according to the “Global demographic trends and future carbon emissions” paper – have “a substantial environmental cobenefit”.

      It’s also worth noting that the natural rate of population change (i.e. excluding migration) is strongly positive in developed countries like the UK and USA, and so policies to stabilise these populations sooner rather than later will also have a significant impact.

      6th November 2013
  5. Chris P said:

    Where the report refers to slowing population growth is there anything to imply that this refers only to slowing growth in the poorest 50%, as Legjoints seems to have inferred? I suspect not and this probably explains the apparent mismatch he sees in the figures. It is wrong to see population as a rich world vs. poor world issue, as many seem to do. Growth occurs across the range of wealthiness of countries, and growth everywhere ultimately affects everyone.

    Also, I think there is a misunderstanding where Legjoints asks:

    ‘by “slowing population growth”. Do they mean that because population growth is slowing, which it is, then this will result in lower emissions than would be the case if population were to continue growing at its current rate? Or do they mean that by taking action to slow population growth we could cut emissions by the stated amount?

    The projections are a range of figures, not one simple extrapolation of a “current rate” (which is a moving figure anyway). All involve assumptions over the actions that will be taken in the future. The question is which actions, or how much action, the world will take, those that lead to the higher projections or those that lead to the lower ones? It is not “this is what is going to happen if we do nothing”., “I wonder what will happen if we do something?” So Lj’s first option is a misunderstanding. I think many people do not appreciate the very great extent to which birth rates are already influenced by actions , actions taken under government policies. These are necessarily taken into account in projections.

    6th November 2013

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