It took me several weeks to make my way through William Catton’s Overshoot. It is not particularly long (about 250 pages, some of which are notes), but I was only reading it off and on.

It was well worth the time. This book is one of the most perceptive, far sighted, and important ones that I have ever read.

I feel like I’ve taken a course from a great teacher who has forever changed the way I look at the world. While very eye-opening (at least for me), the book was also quite sobering. That it was written over thirty five years ago is remarkable (written in the early to mid 70s, published in 1980). Aside from the occasional reference to contemporary politics, this could have been written last year – and still be ahead of its time.

The gist of Overshoot is that humans are living a very precarious existence on temporarily-available carrying capacity, and are soon in for a rude awakening. But it is how Catton arrives at that conclusion that makes the book so valuable.

Catton views the world and human history through an ecological lens. He makes a convincing argument that many aspects of our history that we like to think of as grounded in ideology or politics are, in fact, largely the result of ecological factors. For example, he explains why the US and western European tendencies towards democratic governance is the result of the opening up of the New World, which for many years was a relief valve for European population pressure as well as a trove of natural resources.

He does a fantastic job of explaining the different ways in which carrying capacity of an environment can be modified, and why some of those ways are sustainable and others are temporary. Man has been increasing the carrying capacity of his environment for thousands of years. The advent of agriculture was a major event in that history, The takeover of land from other species and less consumptive peoples has also been increasing carrying capacity for millennia. More recently, industrialization and the drawdown of resources (e.g., the use of fossil fuels in agriculture) has significantly – albeit temporarily – increased the number of people the earth can support.

The problem with these increases in carrying capacity is that they make us increasingly dependent upon them for our continued existence. To the extent that they involve the drawdown of finite resources or threaten to disrupt the complex web of life upon which we depend, we are setting ourselves up for a natural ‘correction’ in the form of a population crash. Catton spends some time discussing classic examples of population crashes in nature (snowshoe hare and lynx) and in human history (Easter Island, Ireland in the 1800s). He investigates the factors that influence how population crashes play out, and how we modern humans have fooled ourselves into thinking that we are exempt from such things. We ignore basic principles of ecology at our own peril.

As Catton recognized even in the 1970s, because we have been so successful at increasing carrying capacity, we behave as if there are no real limits (or that they are far enough away to not matter). Even now (thirty five years later) we seem to think that technology will rescue us, that we will be motoring on into the future in our battery-powered cars and solar-powered homes. That flies in the face of increasing evidence to the contrary, available to anyone who chooses to look.

When population pressure is low, life is good. When it is high, humans (like any other animal) are miserable, act with little restraint, and do things that we would characterize as barbaric. We are now in a transition from the former to the latter, and if you know what to look for you can see the signs all around you. That is not a happy message, but the more we put off dealing with the situation, the harder the fall will be. It is by studying the world through an ecological lens that we will be able to recognize the effects of population pressure and resource depletion, and hopefully mitigate them to some extent. It is by understanding the difficulties that are coming that we can act to minimize their de-humanizing effects and, I hope, leave some chance that our lives and the lives of our children will be well worth living.

Years ago, William Catton (along with some other pioneers of his time) tried to get us to recognize that we will soon be living dramatically different lives than we do now, whether we like it or not, and that it is better to move voluntarily in that direction now than to drown fighting a rip tide. He pointed out that we would be best served by assuming the worst and behaving accordingly, as opposed to the dangerous option of assuming the best and not acting. It’s a damn shame this message that has mostly been ignored in the intervening years, and is only now starting to be revisited by people clearly seeing the effects of peak Everything. Catton said that one of the biggest issues humanity would face would be sheer unwillingness to change, short of absolute crisis. He certainly got that right.

Cheers for reading this far, and I hope you have a good holiday season. If you have the opportunity, get a copy of this book and read it cover to cover. It is now required reading for my children. Below is a list of things that really got my attention as I read this book.

As for me, time to sit down with my seed catalogs and plan for next year’s gardenĀ  :)

Here are some of Catton’s many interesting and valuable observations (in no particular order):

  • Humans have been increasing their numbers on this earth for a long time, but we’ve recently exploded. Back when modern tool-based agriculture took off (several thousand years ago), a person might see population increase by 1% in a generation. When the industrial revolution began, human population was growing about 14% per generation. At the time this book was written, we’d hit 27% per generation! It is that more-than-exponential growth, combined with our enormous drawdown of exhaustible resources, that makes this a very, umm, interesting time to liveĀ  :-/
  • When Columbus set sail for the New World, Europe was struggling with the effects of high population pressure; there were about 24 acres of land per person. With the technologies available at the time, it was difficult to support a population at that level. The introduction of the new hemisphere effectively raised the land per European person to about 120 acres. By the 1950s, we’d spread across the new hemisphere, multiplying rapidly, and there were only 11 acres per person. This population level was made possible only by the use of technology and massive drawdown of resources.
  • Here’s another way of looking at population levels: the number of people that live within an hour’s walking time. When Europeans arrived in the New World, the native population here – assuming uniform distribution – meant that about 17 people lived within an hour’s walk (in reality, it was a factor of three or four higher than that, because people lived in groups). In 1970, Alaska’s ‘uniform distribution’ number was 26. But that number (in 1970) for the entire US was over 2800 people within an hour’s walk. In New Jersey (the most densely populated state) the number was almost 48,000. And in Washington D.C., it was over 600,000! It is easy to see how population density makes the modern world fundamentally different than it was even several hundred years ago.
  • While technology can increase carrying capacity, in practice it typically enables excessive consumption of resources, which reduces carrying capacity (i.e., living less lavishly would allow more to do so). I think of this as a sort of analogue of Jevon’s Paradox.
  • One needs to understand the concept of ‘ghost’ or ‘phantom’ acreage, which is effective acreage that a country or region makes use of in addition to the contemporary growth of organisms within its borders. Both imports of food and the use of fossil fuels in food production (in fertilizer, pesticides, planting, harvesting, and transport) are examples of ghost acreage. A case in point: by the 1960s, Britain got over half her food either from the ocean or from other countries. At (then) current rates of production, her own acreage was not nearly enough to provide for her population, and so she relied (and still relies) on this ghost acreage. The same is even more true of Japan. What happens when fossil fuels become scarce enough that food cannot be cheaply produced and transported in huge quantities over large distances, effectively removing much of that ghost acreage? People will go hungry. In the past, emigrations to new lands could have eased this situation, but we are now out of new lands. By Catton’s measure, humans are now 90% dependent on phantom acreage.
  • The use of the word ‘production’ when referring to extraction of a resource (especially an exhaustible one) is a form of self-deception. An oil company talking about ‘increasing production’ is a lie in the same sense that I lie if I take more money out of my savings account and say my income has gone up.
  • An interesting point: In Japan, it takes about 90 person-days of labor per acre of rice field using traditional human-based farming. In the US, using mechanized methods, it takes about 2 person-days per acre. But in order to achieve that 88 person-day savings, it takes the equivalent of over 800 person-days of energy in the form of tractor, fuel, electricity, and fertilizer!
  • Another interesting observation: Proponents of a massive shift to the use of solar energy are fond of pointing out that all we need to do is capture a very small fraction of the energy of the sun incident on the earth in order to support human needs. Catton points out that, over time, diverting such an amount of energy may well be enough to change the environment in undesirable ways. I haven’t done any investigation into the likelihood of that, but it’s something that hadn’t even occurred to me.
  • The cumulative biotic potential of any species outweighs the carrying capacity of its habitat. In other words, lacking checks and balances, any species has the capacity to overpopulate. Malthus saw that this principle applied to humans; Darwin realized that it was not limited to humans, and was central to the mechanisms of natural selection and evolution. This effect is what allows the snowshoe hare population to quickly recover from predation-induced crashes, and what allows wheat to produce not only enough grain to reproduce but to feed humans as well.
  • The concept of succession is important, and is relevant to this subject in multiple ways. Succession – natural progression of an ecosystem from one state to another – is what you see when a barren lot first becomes overrun with pioneer weeds, which in turn yield to later-stage plants. Eventually this may result in a ‘climax community’, which is a stable, diverse ecosystem. In succession, organisms in one seral stage modify their own habitat, eventually making it unfit for themselves and fit for their successors. Fighting or undoing succession is possible, but is generally difficult and expensive. Farming and gardening are examples of keeping succession at bay; the farmer or gardener is involved in a never-ending struggle to protect crops from hardier and more competitive wild plants and predators. The climax community is sustainable and self-sufficient, and in principle can support humans indefinitely; farmed land is inherently unstable or precarious, but has a higher human carrying capacity. Catton also has a fascinating interpretation of the history of Colonial Williamsburg as an example of a deliberate and very costly undoing of succession in a human environment.
  • A population crash can be thought of as “an abrupt instance of succession with no apparent successor.” Like a typical succession, however, the crashing organism has modified its own environment to the extent that it is no longer suitable to itself. Think of the exploding hare population causing an irruption (sudden rise in population) of lynxes, which in turn causes a predation-induced crash in hares. Or the yeast in a wine vat, whose population explodes in the rich, inviting environment, until the yeast byproducts literally kill off the yeast. Or think of humans…
  • Population crashes are more abrupt in systems where there is less diversity and competition. Simple systems in which there are fewer players and fewer sources of competition have more abrupt and deeper crashes. An extreme example of this is the Brown Lemming; with virtually no competitors, the ratio of population in peak to crash years can be as high as 500 to 1. Other cases? Lynxes (who feed almost exclusively on rabbits) can see population swings of 30 or more to 1. In the case of Ireland in the 1800s, their over-dependence on the potato for food resulted in a population reduction of 2 to 1 (although much of that reduction resulted from emigration, not starvation).
  • Catton points out that modern humans are essentially a detrivore. Detrivores are organisms that live on a previously accumulated store of detritus. An example is pond organisms that feed in the spring on last year’s accumulated leaf debris. Detrivore populations expand far faster than the detritus accumulates; they irrupt and then, as they exhaust the supply of detritus, they crash. Yeast in a wine bottle is a manmade detritus ecosystem. In a similar fashion, man is a detrivore ‘feeding off’ the accumulated stores of organisms from the Carboniferous period (fossil fuels).
  • Catton’s clever depiction of modern, consumptive man as ‘Homo collosus’, and the imagery he uses around this concept, are very effective. I’ll leave the details to the book.
  • All other things being equal, population pressure can decrease when ecological niches are available; conversely, a loss of ecological niches increases pressure.
  • Catton’s discussion of human tool use and environmental manipulation as generalized forms of prosthetics is really interesting. These prosthetics – everything from simple tools to cars, modern buildings, aircraft, and so on – have allowed humans to quasi-speciate and fill many more ecological niches than would otherwise be possible. So in that sense, we’ve increased the carrying capacity of our habitat. But most of our modern ‘prosthetics’ rely on unsustainable drawdown of resources; as resources diminish, carrying capacity will follow, and population pressure will increase.
  • Carrying capacity of a combined area can be greater than the sum of carrying capacities of the parts. This is because in any one local area, carrying capacity may be limited by lack of one particular resource. If neighboring areas have carrying capacities limited by different resources, then trade between the regions will raise total capacity. This is one effect that globalization has had. Globalization, however, relies on fossil fuels for transport of goods; price them out of the picture and carrying capacity will decline. Related to this is the fact that when you have interdependent areas that trade to increase carrying capacity, then that carrying capacity can be diminished by things other than resource constraints. For example, if social unrest disrupts that trade, then carrying capacity will suffer. Catton makes some very interesting arguments about the ecological causes of the Great Depression and the rise of Nazi Germany (that I won’t get into here).