Earth as a Petri Dish: The Problem of Growth

The 1972 publication of Limits to Growth sparked a controversy that has yet to subside. This book argued that if population, resource use, and pollution kept growing on our finite planet, eventually economies would face environmental ‘limits to growth’ – with potentially dire consequences.

Despite the evidence mounting in support of this position, any suggestion that we might have to give up economic growth, or even embrace a degrowth process of planned economic contraction, is typically met with fierce resistance – especially by economists.

Last week I was invited into the Faculty of Business and Economics at the University of Melbourne to defend this radical ‘degrowth’ perspective. I felt like I had been lured into the lion’s den, and was at risk of being eaten alive. But I made it out unscathed to tell my tale, and would like to report on my findings.

As I entered the lion’s den my aim was not so much to convince the Faculty of my view but to ‘deconstruct the debate’, so to speak, in the hope of facilitating a discussion about the areas of disagreement in a fruitful and hopefully non-violent manner.

After considering the objections to degrowth, here’s my summary view of why this ‘limits to growth’ position remains controversial – and why, in the end, the economists that dismiss this perspective are wrong.

What is growth?

If someone is to be for or against ‘growth’ it is important to know what that term means, so in the interests of rigour and clear thinking let’s begin with some definitions. There are four primary ways to understand growth.

First, growth can mean an increase in the energy and resource demands of an economy. This is often called ‘extensive’ or ‘quantitative’ growth. This form of growth represents an increase in the quantity of inputs into the economy (e.g. labour, resources, energy, etc.) in order to increase the quantity of the outputs.

Secondly, growth can also mean using the same resource inputs but doing more with them. This is often called ‘intensive’ or ‘qualitative’ growth. This form of growth occurs when the same resource inputs are used more efficiently, through better skills, technology, or design. This can be understood as increased productivity per unit of input.

Thirdly, growth can refer to increases in Gross Domestic Product (or GDP). GDP is a macroeconomic accounting system that measures the overall market value of all the goods and services a country produces over a given period. This is perhaps the dominant understanding of growth. When most people think of a growing economy, or when our politicians talk of growth, or when growth is mentioned on the news every night, it is almost always in terms of growth in GDP.

Finally, growth can sometimes be used to refer to state of progress where societal wellbeing or overall utility is increased.

These are all legitimate ways to understand the notion of growth but they are not synonymous. One form of growth may or may not lead to another form of growth; some forms of growth may have limits, others may not. Fuzzy thinking about these four types of growth has produced unnecessary disagreement.

Where, then, does the ‘limits to growth’ controversy lie?

Deconstructing the debate

Nobody is against growth in wellbeing, so we can leave that to one side. Furthermore, even economists tend to accept that an economy cannot grow quantitatively without limit on a finite planet.

The real controversy over the ‘limits to growth’ perspective lies in relation to the concepts of GDP and qualitative growth. Defenders of growth argue that there is no reason why we cannot ‘decouple’ GDP growth from environmental impact in such a way that avoids any perceived limits to growth.

These growth advocates might acknowledge that current forms of GDP growth are not sustainable, but nevertheless argue that what we need is ‘green growth’; that is, growth based in qualitative improvement not quantitative expansion.

This view is based in economic theory. It argues that if natural resources begin to get scarce, prices will go up, and this will set in motion two important dynamics. First of all, increased prices will dis-incentivise consumption of that resource and encourage alternatives or substitution, thus reducing demand of the scarce resource.

Secondly, increased prices would incentivise the development of new technologies, new markets, or new substitutes, which will increase the production of the scarce resource and lead to its more efficient use.

Furthermore, when markets are working properly and all the costs of production are ‘internalised’, the prices that result will mean people will only ever consume natural resources or pollute the environment to an ‘optimal’ degree. The ‘invisible hand’ will ensure that utility is maximised.

For all these reasons, modern economists tend to argue that human economic activity will never face limits to growth. Those silly ‘limits to growth’ theorists just don’t understand economics. Growth is good, and more growth is better!

This is the mainstream economic justification underpinning calls for ‘sustained growth’ as the path to sustainable development. In short: all nations on the planet should continue to pursue growth in GDP, while aiming to ‘decouple’ that growth from environmental impact.

Coherent in theory, flawed in practice

I am prepared to accept (for present purposes) that these economic arguments for why there are no limits to growth are coherent in theory. And because they are coherent enough in theory, many people are persuaded by them, making the limits to growth perspective seem controversial or just false. Nevertheless, the attempts to avoid limits to growth are demonstrably flawed when applied in practice.

Tim Jackson, for example, has shown that if the developed nations grew GDP by 2% over coming decades and by 2050 the global population had achieved a similar standard of living, the global economy would be 15 times larger than it is today. If it grew at 3% from then on it would be 30 times larger than the current economy by 2073, and 60 times larger before the end of this century.

Given that the global economy is already in gross ecological overshoot, just imagine the environmental burdens of a global economy fifteen, thirty, or sixty times bigger than today. What makes this growth trajectory all the more terrifying is that if we asked politicians whether they’d prefer 4% growth to 3%, they’d all say yes, and the exponential growth scenario just described would become even more absurd. It seems too much growth is never enough.

Here we see the fatal flaw at the heart of growth economics: the apparent failure to understand the exponential function. By all means, let’s do our very best to decouple GDP from environmental impact – that’s absolutely necessary. But let’s think through the very basic arithmetic of growth and recognise that compound growth quickly renders the growth model a recipe for ecological and thus humanitarian disaster.

In short, the main problem with the growth model is that it relies on an extent of ‘decoupling’ that quickly becomes unachievable. Granted, we might be able to produce food more efficiently than we do today, but we cannot eat recipes!

To make matters worse, recent evidence has debunked the widespread myth that the developed nations are already in the process of achieving significant decoupling. It turns out that what we’ve mainly been doing is out-sourcing our energy and resource intensive manufacturing and ‘recoupling’ it elsewhere, especially in China. So much for green growth. We’re just cooking the books.

As I have argued elsewhere, continued growth in GDP is also incompatible with the goal of avoiding dangerous climate change.

Earth as a Petri dish

I think everyone who casually dismisses the limits to growth perspective should be given a Petri dish with a swab of bacteria and watch as the colony grows until it consumes all the available nutrients or is poisoned by its own waste.

In that light, I ask you to imagine a world of seven billion people, trending towards eleven billion people, all aspiring to the Western way of life, on our one and only planet, and consider for a moment whether the first limits to growth theorist, Thomas Malthus, who is often ridiculed, may yet have the last, tragic laugh.

From a distance, I think Earth would look very much like that Petri dish I just mentioned.


The paperback of Sufficiency Economy is available here. For those unable to pay or who would like an electronic version, the pdf is available on a ‘pay what you want’ basis here.

The paperback of Prosperous Descent is available here. The pdf of this book is also available on a ‘pay what you want’ basis here.

14 Responses to “Earth as a Petri Dish: The Problem of Growth”

  1. Steve Gwynne says:

    Hi. Really enjoyong your work and find it inspiring. My question is what was the counter argument to your view that the exponential growth rate was absent from their perspective? Thanks

  2. Steve Gwynne says:

    Another question. Do you think it is possible to have sustainable economic growth by solely applying the principles of recycling, reusing, remaking, repurposing and using renewables to carry out economic activity and thereby with immediate effect stop the extraction of non-renewable resources as well as stopping any further the destruction of non-human habitats?

  3. jonathan Rutherford says:

    Very good article Sam.

    The problem with exponential growth is part of it, but not sure its the full reason why people can’t accept.

    I think the techno-fix faith is simply huge. Humans wizadry will overcome any barriers.

    Relatedly, people simply can’t believe that there will be fundamental geo-physical/enviro limits to human ‘progress’. Growth, change, ever greater accumulation of wealth etc, is so deeply embedded in the fabric of our capitalist culture that people can scarcely conceive – and I include myself in this – of a steady state of existence. It contradicts our ever day experience (in urban capitalist societies). We are the masters of the universe! How can nature restrict us! This seems impossibe TODAY to most people….no matter what the evidence says….

    Oh and then there is the comforts and distractions and simple material privileges that the rather inconvenient reality of ‘limits’ to depressing for most to dwell on for long…(especially when every part of the culture encourages them not to).


  4. jonathan Rutherford says:

    That last point – about the inconvenient nature of limits – raises the point that maybe most people, somehow, know that we face limits. But caring about it, let alone doing something, is too hard. No rewards for that…and besides, the footy’s on tv this friday!

  5. Dave Gardner says:

    Extremely well-written. Thank you for this. We’ve honored it on our Wall of Fame today at Growth Bias Busted:

  6. Thom Hawkins says:

    Sam, did you get any respect?

  7. Samuel Alexander says:

    There was no disrespect from either angle. A throughly collegial discussion – with much less push back than I was expecting.

  8. Samuel Alexander says:

    Thanks Dave!

  9. Samuel Alexander says:

    “My question is what was the counter argument to your view that the exponential growth rate was absent from their perspective?” It’s not that exponential growth is absent from the economic perspective. My argument is that mainstream economics doesn’t understand the implications of it. The counter-argument is that “we will be able to decouple/dematerialise that exponential growth from environmental impact sufficiently”. That is coherent in theory but I don’t buy it all. The extent of decoupling required is simply too great.

  10. Samuel Alexander says:

    You ask: “Do you think it is possible to have sustainable economic growth by solely applying the principles of recycling, reusing, remaking, repurposing and using renewables to carry out economic activity and thereby with immediate effect stop the extraction of non-renewable resources as well as stopping any further the destruction of non-human habitats?”

    I would ask what form of ‘growth’ you are referring to? It’s important to specify otherwise we can’t think clearly about these issues.

    Reading between the lines, I’d respond to your question by saying that recycling, reusing, remaking, etc. are absolutely critical to a sustainable economy. But we need to ask what we’re aiming to achieve? I think most people still think that those types of practices, plus technology, plus market mechanisms, will allow the global population to eventually live Western-style lives. As I argued, I think the extent of decoupling required to make that model sustainable is simply unachievable. We shouldn’t be aiming to universalise affluence. We should be aiming to universalise sufficiency. That’ll be quite challenging enough.

  11. Steve Gwynne says:

    Thanks Sam. Yes I see what you mean regarding the exponential factor in that if the global economy increases in size then existing available resources which have already been extracted are hardly going to multiply in order to absorb these exponential increases even if renewables and other types of ‘re’ economic activities are utilised. This means more resources will need to extracted to some relatively high degree as is being demonstrated with the high levels of extraction taking place in China and Africa. Obviously this type of growth is extensive/quantative.

    With regards the possibility of completely decoupling growth from environmental impact then obviously the stats you quote do not substantiate this perspective. The growth I was referring to was intensive/qualitative in the main, however I was perhaps more recfering to an economic situation whereby existing extracted resources are utilised ad infinitum which might refer to another new type of growth whereby as resources become available as a result of household/industrial goods being thrown away then these resources are repurposed. In a way it is not growth at all but if not how would one describe the flow of materials within a circular economy. In a way it is a type of qualitative/intensive growth but one that is based on increased productivity per unit of resource. Therefore productivity is measured differently as a measure of how many times resources complete a cycle within a circular economy.

    A last point. It occurs to me that within conventional understandings of qualitative growth surely there is always a downward pressure on unit price in order to reflect the effeciency gains which means that unless more of a good or service is purchased Gdp growth will tend to stagnate which seems to be the case in many developed countries and why govts places so much emphasis on achieving 2% inflation aka as artifically inflating/deflating interest rates in order to create/decrease value, all of which is decoupled from actual economic impacts.

  12. Thom Hawkins says:

    Connect the dots between techno-optimists/ecomodernists love for endless growth through “decoupling” human impacts with delusional technical marvels and the mega-conglomerate oligarchs stranglehold on the economy and political power:

    “The San Francisco Bay Area is known as a liberal stronghold, but it has emerged as the state’s top spot for donations to Republican presidential candidates, according to a Los Angeles Times analysis. Candidates and their super PACs have collected $13.4 million in the area, mainly from Silicon Valley tech moguls. It appears that Orange County’s donors are taking a more cautious approach, giving just $1.6 million so far this cycle.”
    LA Times

    Even when climate change is burning and flooding our land and communities, killing thousands globally and locally, we believe that homotechies are still immune to natural forces because that is what the big money is telling us over and over again–they control the story.

  13. Brian Greene says:

    Thanks Sam for making your seminar presentation available. Like others I am interested in the questions you received and the group discussion as well.

    Could you provide a bit more detail on the discussion, and the participants’ questions and ideas?

    I had a look on the university’s website hoping to find more information about your talk but haven’t had any luck. Do you remember who invited you to give your talk and or who came along? I’ll be honest I am surprised that a business/finance department was interested in degrowth so would I’d like to chase up their work and to see if any of it fits alongside degrowth ideas. I’m just starting to try to get my head around it all and this would be new to me.

    Cheers from NZ.


  14. Bill Everett says:

    Nice outline, Samuel. I would like more explicit substantiation of the implicitly obvious claim that decoupling to allow “unlimited” GDP growth quickly leads to unattainable rates of decoupling. I’ll try to find the time to do the required modeling (unless you have a quick and easy demonstration readily available).

    As an aside, I really like the Petri dish analogy for people with a “flat Earth” mentality.

    — Bill

  15. […] This faith in the god of growth is fundamentally misplaced. It has been shown, for example, that for every $100 in global growth merely $0.60 is directed toward resolving global poverty. Not only is this an incredibly inefficient pathway to poverty alleviation, it is environmentally unsupportable. […]

  16. […] dismisses the idea that there is a limit to how many people Earth can support should be given a Petri dish with a swab of bacteria. Watch as the colony grows until it consumes all of the available nutrients […]

  17. […] dismisses the idea that there is a limit to how many people Earth can support should be given a Petri dish with a swab of bacteria. Watch as the colony grows until it consumes all of the available nutrients […]

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