Breaking boundaries but not population taboos

The book Breaking Boundaries by Johan Rockström and Owen Gaffney explains the basics of how the Earth works and how humanity is rocking the boat, ecologically speaking. While describing monumental challenges, it views the future with optimism. Despite having a chapter dedicated to population, it fails to acknowledge how larger global populations reduce our chances of achieving sustainability.

by Pernilla Hansson

Breaking Boundaries: The Science of Our Planet explores limits to human exploitation of the Earth’s systems, stressing the urgency to act and lamenting the inadequacy of actions so far. It is well-written and through the use of metaphors and personal stories the authors manage to make otherwise rather dry source material into a compelling read. The authors are Owen Gaffney, analyst and journalist, and professor Johan Rockström, an influential researcher in climate and sustainability science.

Even if some parts may be somewhat confusing and jump between topics, the chapters manage to explain technical terms so that anyone can understand them. The book is split into three sections or “acts,” through which Rockström and Gaffney take the reader on a journey exploring the way the biosphere works, important revolutions in human history and their consequences, the current state of the Earth’s support systems, all the way through to what needs to be done to live within their identified planetary boundaries. The final section of the book contains references for each chapter; however, it is not always clear where any stated fact comes from.

The question for this article is what Rockström and Gaffney have to say about population growth. Reviewing the table of contents, there are two intriguing chapters in act three titled “Feeding 10 billion people within planetary boundaries” and “The population bomb disarmed.”

But let’s not get ahead of ourselves. The first act focuses on Earth sciences, the history of the Earth, with the advent of complex life and several mass extinctions, through to human evolutionary history. It explains the essential basics to understanding Earth science, such as the three stable “thermostats” of Earth: hothouse, icehouse, and snowball. Importantly, the first act introduces the Earth’s self-regulation systems, which are discussed throughout the rest of the book. Rockström and Gaffney also highlight the disturbing transition from the Holocene, which had an unusually stable climate that allowed humanity to flourish, to the Anthropocene epoch, whose true self we have yet to see, but which we expect will not have that same stability.

Act 2 explores the scientific basis for understanding the health of the planet and how we are changing it. The dangers of passing planetary tipping points for safe use of the biosphere are laid bare, as well as the risk of the domino effect if one tipping point interacts with another. It warns of the difficulties humanity will face in a warmed and destabilized world and asserts that we have already passed 4 of the 9 planetary boundaries (see graph below).

The planetary boundaries approach, introduced in a famous 2009 paper by Rockström et al., identifies nine major ways in which humans disrupt the biosphere, any one of which could undermine humanity’s life support system if sufficiently disrupted, and attempts to quantify the limits for “safe” disruption. Neither the original paper nor subsequent publications specify the role of human numbers or the size of the human economies in driving us past these boundaries. Figure from their 2015 paper. Note that the existence of planetary boundaries, at least with respect to biodiversity, is the subject of much debate.

In the final act, which is also the longest, the idea of planetary stewardship is established. Six system transformations are needed, according to the authors; energy, food, inequality, cities, population and health, and technology. A specific chapter is dedicated to each system transformation, exploring different aspects of what needs to be done and how we are doing. This section also explores the role of the economy. Rockström and Gaffney focus on the need to change the economic model into one that no longer promotes endless growth but rather supports societal goals for a sustainable future. They stress how the economic system is one of the most important tools for the needed transformations, and see reasons to be optimistic, as sustainable technologies and business models are becoming more profitable.

Population reduction, the ultimate taboo

This is all well and good, and makes for excellent reading about our current predicament and possibilities for change. But what does the book say about the role of population? Unlike many recent scholars, Rockström and Gaffney believe the current global population, or even one several billion larger, is ecologically sustainable. Unlike many population advocates, they believe population growth will cease without dedicated efforts to end it. One place they indulge this optimism is in a chapter aptly named “Feeding 10 billion people within planetary boundaries.”

Our food system is at the centre of many of our largest global environmental problems and could all by itself undermine the goals of the Paris climate agreement. Rockström and Gaffney adequately portray the problems of our agriculture: that 70% of all withdrawals of fresh water are used for food production, how the way we capture and produce our food is the main driver of the current mass extinction of species, and how food insecurity may increase due to climate change (but not that it is already increasing due to population growth). They state that 50% of our planet’s habitable land has been transformed for agriculture, and that we need to follow the Half-Earth principle of keeping the other half intact.

Somehow, though, the authors fail to mention that even if we only occupy half of the habitable land with our agriculture, we have already severely altered over 75% of the planet’s land surface, as stated in the 2019 IPBES report. Or that people make many other demands on the landscape beyond agricultural production. Or that recent scholarship suggests that achieving Half-Earth levels of biodiversity protection will demand much smaller overall human populations, perhaps 2-3 billion maximum.

Rockström and Gaffney are optimistic that humanity will be able to feed everyone while operating within the planet’s boundaries, if only we completely overhaul the current system by adopting a healthy planetary diet, reducing food waste, and transitioning to more circular farming. The fact that climate change will probably decrease crop yields is mentioned, but not other instabilities, such as we have seen in disruptions to food markets after Russia’s invasion of Ukraine.

Back in chapter 4, they asked a pertinent question. Agriculture will need to draw 15% more water to provide food to our growing population; where will this come from? The authors don’t answer the question in that chapter, nor do they answer it in the chapter on feeding 10 billion people, despite having published an article which explores it. In the book they mention the worrying fact that water usage may be plateauing because there are few rivers left undammed or un-siphoned, but not where this 15% increase in water consumption will come from. Nor do they provide a convincing explanation for how “circular farming” or other technofixes will avoid agriculture’s continued displacement and extinction of other species in a world of 10 billion people.

The specific chapter in Breaking Boundaries that focuses on population growth, apart from being the shortest chapter, seems muddled and unclear in its message. On the one hand, Rockström and Gaffney ridicule people who say population size is a problem, implying that population activists think population will continue to grow exponentially so that we may reach 100 billion soon. They suggest that believing population is an important factor means believing that no other factor is important. These misrepresentations stand at the beginning of the chapter. Not off to a promising start.

On the other hand, towards the end of “The population bomb disarmed,” coming out of the blue, the authors state that “providing family planning and education to girls has the potential to avoid 85 billion tonnes (93 billion tons) of carbon dioxide emissions this century and to stabilize global population at levels that are manageable.” This is great! But that is all we get on that topic, and only after disparaging people who are advocating exactly this. There are clearly ways forward for population that can help limit climate change and help stay within other planetary boundaries, yet they remain unexplored in this chapter that supposedly is devoted to the problem. The chapter seems both to state that population is now a solved issue as the global growth rate has subsided, while simultaneously acknowledging that efforts to decelerate growth would make a large contribution to staying within planetary boundaries. Could it be that the two authors don’t agree on this issue? Either way, the message of this chapter is thoroughly muddled.

While population growth rate has decreased these past 50 years, the annual growth in absolute number of people has stayed relatively stable around 80 million. Data from Worldometer.

To infer that a falling growth rate ensures population is stabilising is a misrepresentation we would not expect from a data scientist such as Rockström. Rockström and Gaffney state that the rate of population growth peaked in the 1960s and is now half of that. But they don’t say that the number of people added to the global population this year will be even greater than it was in the 1960s. For 50 years it has been a fairly steady, undiminishing 80 million per year. It is a smaller percentage of what is now a much bigger population, but it’s the increment that matters, not its percentage of the current population.

Suppose you are driving toward a cliff at 60 km per hour. After one minute, you’ve travelled one km. In the second minute, you increase the distance you have travelled by 100%. In the sixth minute, you add another km to the 5 you already travelled: a 20% increase. In the hundredth minute, you increase the journey by only 1%. Do you say, “don’t worry, we’ll stop before we go over the cliff: look how our travel rate has fallen”? You’re still travelling at 60 km per hour and the cliff is closer than ever.

Even if the peak growth increment has occurred in global population increase, this doesn’t mean that there is nothing more for population advocates to do. Just ask the hundreds of millions of women in developing nations who desire but cannot access contraceptives, or who still lack bodily autonomy. This is a double standard not applied to other solutions Rockström and Gaffney advocate: just because positive change has begun happening in areas such as decarbonising energy or protecting forests, they don’t suggest we rest on our laurels and just hope the projected trajectory continues. So why do they do that when talking about population?

Another rather unscientific statement is found in this chapter. Rockström and Gaffney state that an “infinite exponential growth is not possible in the real world; instead, everything eventually slips into an ‘s curve,’ as growth rates slack off.” This implies that some magic hand of restraint will lower birth rates before resource scarcity forces a population die-off. But not “everything” has such happy endings: in nature, overshoot and collapse is a common pattern. Just ask the Greenland lemmings. A nice “s curve” stabilisation (or better still, a gradual rather than catastrophic decline) can only be achieved by making small families the norm. But Rockström and Gaffney invoke the inevitability of the “s curve” to argue that no intervention is necessary. It is a particularly odd argument in a book on how we must consciously and proactively work to avoid overshooting planetary boundaries. Another example of the double standard applied to population.

Interestingly, “The population bomb disarmed” mentions that the population in 2100 could climb to 11 or 12 billion. Yet the authors themselves devote a whole chapter to the many challenges and difficulties of feeding 10 billion people within the planetary boundaries. When they talk about feeding future populations, they say it can probably be done. Probably is not good enough when it comes to people’s lives. What happened to the precautionary principle?

Rockström and Gaffney are optimistic about the necessary changes to achieve global sustainability and believe we are heading in the right direction. They seem nonchalant that this can be achieved with humanity’s current population trajectory. This is great news if it is true. Then imagine if resources were also funnelled into promoting small families and providing contraceptives and education. We could create a world with a greater buffer to protect ecosystem services for people, and more habitat to share with other species. How much better off would we be if we also took population matters seriously?

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16 thoughts on “Breaking boundaries but not population taboos

  1. Yes in regard to Rockstrom’s new book, I find it hard to understand how he argues the Earth can support 10.2 billion humans when all environmental indicators are in decline with 7.9? His scenarios for how this can happen are not just optimistic but unrealistic.

    1. One of the most dangerous mistakes we make in thinking about sustainability is underestimating its difficulty. We start adding up all the great efficiency improvements we could make in theory, and get unrealistic ideas about what is possible.

  2. I’m starting to think that there a problem here: scientists who are not specialists in agriculture (and even some who are) very often do not actually understand agriculture, yet they’re telling everyone what agriculture can and should do or not do, what we should or should not eat, etc. They’re very often wrong.

    This problem occurs in many other fields. I often hear practicing doctors ranting about university doctors who never actually see a patient… obviously, you do need to do theoretical research, but when theoretical research is applied exclusively to a practical, hands-on domain by people who have no hands-on experience, disasters often ensue.
    Food (and fiber, drink, etc) production is extraordinarily complex, varying, and context-dependent. You can only understand it in its entirety if you do it, and even that is not enough, as it takes generations to see the long-term changes, and what works wonders now might make it impossible to grow food in the future.

    We should look at Sri Lanka, where an abrupt transition to organic agriculture is causing a very severe food crisis. Long-term sustainability in food production is only possible if you accept lower yields. The high yields we have now are unprecedented and not attainable in any other way except by wrecking the environment and depleting non-renewable resources.

    I am *trying* to do organic, draft animal-based, regenerative, no-irrigation agriculture. I do most things by hand, no chemicals. I compare my work to that of neighbouring farmers and hobbists. I constantly have to explain why I don’t want to use too much water or machinery or why my produce is smaller or why I have so many weeds. Yes, the food is high quality, the land is healthy, and I’m not depleting rivers. But I’m also nowhere near producing enough to have an economically sustainable business in today’s world. It’s also very hard on the body to work like this, and no one wants to do it.

    The idea that we can feed 10 billion people “sustainably” is madness. And a very dangerous thing to convince people of.

    1. “Long-term sustainability in food production is only possible if you accept lower yields.” This is a key point that people are loath to accept. But certainly, up until now, the ways we have found to increase agricultural yields have all come at great environmental cost.

      Even if we could find environmentally benign ways to increase agricultural productivity, the ultimate “yield” is more people, which brings numerous other environmental problems!

      1. That’s one of the many problems with the “feeding 10 billion” idea: it leaves all the other problems associated with overpopulation unchanged.

        Also, agriculture isn’t used just for food.

  3. Population confuses people who don’t look at it carefully. Half the world, approximately, got to a 2 child/woman norm, and continued down to birthrates as low as one per woman. They got richer. But 20% or so still maintain fertility rates above 4 and remain poor. So the rapid exponential growth and population warnings of the 1960s led to halving of world average fertility rates over a forty year period from 1970 to 2010 (from 5 to 2.4). But declining fertility was offset by the rising numbers having children. So growth has been roughly linear since 1970, meaning a constant annual addition of about 80 million per year. In 2020, 140 million births, 59 million deaths, 81 million increase. Doubling world population over 49 years from 4 billion in 1974 to 8 billion by 2023. So, yes, much more effort and awareness is needed to get the remaining fertility transitions accomplished in the face of failed states, religious objections, and, above all, low status of women, poverty, cultures that value large families and motherhood, and lack of access to affordable contraceptives.. Looking at industrialized, urbanized countries, people conclude that population decline is a problem. Looking at consumption in those countries, however, they are overpopulated and wrecking the biosphere. Rapid growth in poor countries also contributes to deforestation and loss of biodiversity. The lungs of the planet are being cut down. The alternative to cutting fertility is rising mortality. Humanity has, by continued population increase, chosen higher mortality on a damaged planet.

  4. Philip and all, I’d be interested in hearing your take on all the appeals (including from the UN secretary-general himself) to unblock grain from Ukraine – and fertilizers, etc.
    I understand the urgency, but we need to reflect on the folly of relying on a few countries to feed most of the global population, of overcrowding regions with very little food-production capacity (Middle East, SS Africa…), of wasting good agricultural land on infrastructure, urban expansion, tourism… (I’m thinking Italy, but it’s the same in many wealthy countries)
    I’d also be interesting to know whether Ukraine’s stupendous productivity is only due to its black soil, and what the environmental impact of such production has been. Although it might be unfair to pick on Ukraine right now.

  5. Gaia, the points you bring up are good ones. Folly indeed! In the short term, though, I support efforts to get grain to hungry people, just as I support peace efforts around the world, even though war is sometimes an effective means of population reduction.

    Norman Borlaug said it well over half a century ago. If we develop means to feed and otherwise sustain large numbers of people, we take on the responsibility of limiting our numbers consciously via contraception.

    The problem, as has become clearer in subsequent years, is that Borlaug’s and others’ humanitarianism was enacted within a larger context of endless growth. The world is deeply, deeply committed to that folly. And it’s a folly that puts us in no win situations in the short term, like “let people starve, or scramble to find them food so that they can continue to increase their numbers.”

    1. The problem is no one is SAYING there’s something wrong in being so dependent on imports. As long as we take this state of affairs as normal, and getting food from the other side of the world as a God-given right, things will never change.

      I am super pro-Ukraine in this, but Russia does have a point in saying “you can’t put sanctions on us, and then want our stuff” (conveniently omitting the stuff they’re stealing from Ukraine). We put ourselves in the situation in which we are dependent on a single country or two for vital things – and not just Russia, Belarus, but also many others.

      I too don’t want to see people starve! It’s like the ethical dilemma when someone make a terrible mistake, something you warned them about, but nothing bad happens. On the one hand, you’re happy for them, and would feel guilty for hoping they’d learn a lesson, on the other hand you do want them to learn a lesson. Maybe this is a terrible thing to say but we’ve all been on the other hand to, and learnt… but humanity keeps making the same mistakes!

      1. The neoliberal economic approach argued that dependence on imports is a positive good. Good in that countries can specialize in what they are best at, leading to efficiency improvements overall. Good that it makes countries dependent on each other, giving them an incentive to live peacefully together.

        As others have noted, even previous winners in globalization are starting to experience more of its drawbacks. Nations are starting to take steps to secure essential resources, keep essential industries within their own borders. It will be interesting to see how far these trends go.

        Hard to imagine a more essential resource than food. Food and water.

      2. I do wonder about the peace thing. By making sanctions effective, economic interdependence could help stop the worst actions by certain countries.
        The problem is that sanctions aren’t always effective; it depends on the regime and the situation.

  6. There is one part of the population debate that I don’t see at all when the topic of too many peoples and resources. I see in your article that we have to get girls under control by getting them on contraception which also means abortion. The women on this planet have been selected by elites to give up their natural right to be left alone about a private decision. It is their “right to choose” by refusing to use contraception. I don’t hear any plans about getting boys and men under control with regard to their fertility and reckless sexual behaviors. Shouldn’t a man only be able to impregnate a woman 2 times to produce only 2 children for his entire lifetime. He has a choice to do whatever he wants while you are controlling young girls and women’s birth rate. Make men less sexuality active and you will see less of the “population bomb”. You also target the poor – there are too many Africans”, targeting the most vulnerable people on the planet. In reality there are too many rich people living vain, vacuous lives, indulging ever whim of their desires. Let’s start by saying if you are rich and want to reduce population, start with yourselves. Get rid of your wealth, get rid of third world debt, let resources stay in the country from which they originate. Shut down, airlines, cruise ships, mansions, movies, the internet because they soak up too many of the resources that you are worried about. It’s as plain as ever that you want to get rid of poor black people, ruin families and to be the “owners” of the planet. Even the LGBTS want to control womens fertility through paid use of a woman’s womb. If you want women to have only 2 children then you should ban paid surrogacy because they are taking one of the two children that you think a woman has a right to have. Surrogacy exploits poor women. It is misogynistic , rascist, and is using up a valuable resource- a woman’s fertility’s. You support forced abortion and forced contraception on half of the population-offer yourselves up for the culture of death first.

  7. The review is right on target. They seem to not understand the basics
    To my way of thinking the fundamental problem is the”need ” for the economy to grow
    Has the Overpopulation Project consulted with economist’s like Tomas Picketty, who are concerned about the poor

    1. There’s a very big literature about the need for “de-growth” (or steady-state economics, etc). Part of the literature ignores the population problem, part doesn’t. Check out the Growth Bias Busters project, they have great guests including one from this website 🙂

  8. Great article, Pernilla. Please let us know when Rockstrom or Gaffney reply.

    Perhaps share with us what they say in defense . . . or in agreement. ( Who knows, maybe all of us are wrong! )

    You might also invite them to our population taboo clinic. We have medicine for their ailments, right? : )

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