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The Limits of Growth: The 30-Year Update - A Review

Posted Dec 23 2008 12:53pm
The Limits to Growth was originally published in 1972 and has subsequently been updated twice at the 20- and 30-year marks of the original publication. Commissioned by the Club of Rome, the authors created a computer model, World3, to look at the relationships between exponential growth, human systems, environment, and finite resources. They do not try to make predictions about the future with the World3 model –variables such as the amount of available resources, the capacity of “sinks” to absorb pollution, or the maximum productive capacities of soil or technology can only be educated guesses – but rather, seek to explore possible trends when accounting for certain assumptions in the variables.

A little aside: the “scientist” in me was very pleased when reading this book. The authors make sure to clearly and consistently explain the limitations and assumptions in the model and its various scenarios. They remind us – as all good scientists should – that we should be skeptical, yet respectful; we should look at their ideas with honest, open eyes and minds, but also be willing to come to different conclusions about what we see, to disagree with their assumptions, because nobody really knows.

They approach the idea of limits from a systems perspective – focusing on the “big picture” – this does not mean that systems analysis does not look at individual elements, but it looks at individual elements in relation to other elements or how that element affects the whole. They do not seek to gain insight about any one variable in the model on its own.

A main focus, and thus part of the purpose of the model is to explore the limits of exponential growth in a finite world. The concept of exponential growth is very important, though not well understood. This isn’t because the concept is hard to grasp, there are many examples that clearly illustrate it, it is that the ramifications of understanding the situation are complex and face us with real limits that call for a fundamental change in the nature of our daily existence and interaction with our environment. An easy way to begin to look at exponential growth is this question, “Why does the population continue to expand rapidly in absolute numbers even as the birth rate is declining?” The short answer is the age distribution of the population and the sheer size of the population. Though couples are choosing to have fewer children, there are more couples coming of reproductive age, thus we end up with a net increase.

Perhaps now we can understand how the repercussions of something consequential like population, resource demand/availability, or pollution can be affected by exponential growth. This is why when someone says something like “we have a 150 year supply of ‘x’ resource left” it is very misleading. These figures are derived at the consumption rate at the time, the 150 year figure only applies if there is no growth in demand for the resource over time – this is something that is not likely to happen unless we reach very harsh limitations.

The World3 model used to chart the possible interactions of variables such as food/person, services/person, consumer goods/person, industrial output/person, population, resources, pollution, ecological footprint, life expectancy, and human welfare, is inherently limited in that it doesn’t (because it is too complex and speculative) account for war, political strife, corruption, or even all of the variables affecting those mentioned above. The point of the model is not to make predictions of the future, but to give a rough idea of what could lie ahead, what our possible future could look like, what problems we could be faced with, what the trends show, etc.

What I noticed immediately was that accounting for just one variable – even completely – was not enough. Simply reigning in population does nothing to stymie pollution or land degradation, just as simply reducing pollution does nothing to increase the abilities of a limited amount of land to feed an exponentially growing world. What you are left with are three basic scenarios, all involving overshoot as the authors believe our consumption is already above sustainable levels: oscillation, collapse, or equilibrium. Of course none of these scenarios are exclusive, even a situation of equilibrium might have periods of oscillation or scarcity due to delays, which will be discussed further below. There are also relative degrees of these scenarios, measures to account for these limits such as land stewardship, voluntary simplicity, pollution abatement, and family planning are taken and provide nuanced differences in results.

A scenario of oscillation basically means that the population would overshoot the planet’s carrying capacity (ability to provide all the services and goods the population needs) – but not to a point at which the planet could not recover - this would lead to periods of scarcity and die off leading to the reduction of the population below the carrying capacity of the environment. This could happen voluntarily, involuntarily, or in some combination. If crisis hit, we could understand that we’ve overshot of planets ability to sustain us and take whatever measures we can to come back in line with that ability, or we could allow Mother Nature to bring us back in line with that capacity via famine and possibly disease. Remember again, this model assumes no war or political strife, which is not likely to be the case in times so desperate. The scenarios of collapse, on the other hand, occur when no precautions or abatement measures are taken – or they are taken too late – and the planet loses its ability to completely recover. The scenarios often show a drastic reduction in available food, resources, and life expectancy, along with increasing pollution. A dramatic reduction in human population follows and the material standard of living can not be brought back up to previous standards - at least not on timescales useful to humans. The most desirable scenario, equilibrium, could involve times of over exceeding the carrying capacity, but the long-term trend is one in which the resources needed to sustain the population are above the demands of the said population. This could be brought about with sound social, industrial, and agricultural policy, pollution abatement, population reduction, but most importantly, with a voluntary reduction in desired material standard of living - this does not mean us all living like paupers, but I think the days of 3 TVs and 2 computers would be long gone at that point.

Part of the problem we face is the reality of delays and feedback loops. Pollution emitted from cars today do not immediately begin affecting the atmosphere – on the contrary – it will be many years before we feel the full affects of today’s pollution. Meaning, say this was a perfect world, and we ceased any and all pollution starting now, we would still see an overall increase in pollution for a few decades before it began to level off and decline. This is what muddies the picture of the future even further, how long does it take for the full affects to be felt? Nobody is completely sure because, of course, we are in uncharted territory. There are also feedback loops, both positive and negative to (try to) account for. A positive feedback loop is one where an effect on a variable in one direction causes it to move even faster or farther in that direction. Agriculture and population are the easy example of a positive feedback loop. More population can be sustained as humans move to agriculture, but as more people are born, more land has to be cultivated at an accelerated rate. A negative feedback look is where an effect on a variable in one direction causes a decreased response. An example of this could be the unsustainable extraction of water from a river. As more water is drawn out, less water flows to the sea, perhaps ceasing to flow all together.

These elements, the various choices humanity can make along the way, and all the variables that were not included in this model limit what one can glean about the future from a computer. But what it does show is the importance of looking at a system not just its constituent parts, of understanding the spiral effect of feedback loops and exponential growth, of understanding and accounting for delays where possible, of the importance of far sighted thinking and full accounting of the “costs” of the things that make our society possible, and that we understand that there is such a thing as too late to avoid collapse. We must find and respect limits, explore alternatives, and be ever-mindful of our ability to leave a world that is either better or worse than the one had, but only if we act - and act with foresight, humbly, and together.

This was an excellent book that I will be adding to J's Recommended Reads. I highly recommend it to anyone who wants to understand systems thinking, feedback loops, delays, or the many possible outcomes for our future.

I probably won't post again until next week due to the holidays. I made (and have planned) a couple of new recipes, but I am going to wait to post them until next week.

From the both of us here at Veg*n Cooking, we wish you a happy, safe, and non-consumerist holiday (like how I added that in?).

'Til next time!
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