Another semester has begun, and I’m teaching an entry level course in environmental studies for the eighth consecutive academic year. I enjoy doing so for a number of reasons. One is that the students coming into first year arrive with a wide array of previous knowledge and experience. Some have come from high school programs that provided them a very strong foundation in the natural sciences and in environmental research, while others are almost petrified at the notion they might be required to reproduce a chemical formula or calculate anything more sophisticated than a mean average on the midterm test. Getting this very heterogeneous group up to the level where they can successfully pursue further courses in environmental studies (whether they actually choose to do so or not) is a fun challenge. The students themselves are generally fun, too – they haven’t yet been worn down by the grind that is an undergraduate degree program.
It’s also useful for me as a researcher to be continually reminded of the basic, fundamental concepts on which my discipline and its understanding of the world are based. Two such concepts I would like to discuss here are ones that can be found in the first few chapters of nearly every environmental studies textbook written in the last twenty years: Paul Ehrlich’s I = PAT model, and Wackernagl and Rees’s ecological footprint equation. Both represent imperfect attempts to illustrate in simple terms to a wide audience the scale of human impacts on the natural environment. One of these I find very useful in teaching undergraduate students, the other less so.
The one I find most useful is Ehrlich’s I = PAT model. The letters are as follows: I stands for Impact, P is for Population, A is for Affluence, and T is for Technology. Sometimes the A gets replaced by a C for Consumption, an important point to which I’ll return in a moment. Ehrlich is a professor at Stanford, and is often described as a neo-Malthusian. For those who don’t know, Thomas Malthus was a British clergyman who in the early 1800s wrote essays warning that human population numbers cannot grow indefinitely, but are inevitably checked by conflicts, disease, or limited food supplies. In the late 1960s, Ehrlich wrote a now well-known book called The Population Bomb, in which he warned that a rapidly growing human population was in imminent danger of outstripping the world’s available resources, and would inevitably decline in Malthusian fashion if urgent steps weren’t taken. Notable is the fact that, at the time Ehrlich was writing, the global human population was approximately 3.5 billion: roughly half what it is today, but more than 3.5 times larger than what it was in the days of Malthus.
The I = PAT model is one way by which Ehrlich sought to communicate the nature and scale of human impacts on the environment. The model is more of a conceptual one than a numerical one, and it argues that the scale of a given population’s impacts is equal to the product of P * A * T; that is, the number of people in question, multiplied by their level of affluence and their technological sophistication. The implications are straightforward. A small but affluent population with the most sophisticated technology has a much greater potential impact on the environment than a larger but less affluent population with access to only modest technology. Further, even a modest increase in population (or any of the other factors) would have a considerable effect on their overall environmental impact. This is easily illustrated by imagining that the numerical values for P, A and T were all equal to 3, meaning the environmental impact equals twenty-seven (27 units of what, who knows, it’s just 27). Now imagine that over the course of time the population increases to 4; in that case, the overall impact of the population jumps to thirty-six. In other words, an increase in population by one unit does not simply add one unit to the total impact of that population on the environment (which would be represented by P+A+T) but instead leads to an increase of nine units of environmental impact.
There are many real-life that suggest Ehrlich’s model is quite plausible. Take as one example a comparison of historical greenhouse gas (GHG) emissions between Canada and Mexico. For the monitoring period 2002-2004, Canada is reported to have emitted an estimated 740 megatonnes of GHGs while Mexico emitted 686Mt. The difference between the two is less than ten percent. However, the population of Mexico is more than three times larger than that of Canada, so if we convert GHG emissions to per capita emissions, we find per capita emissions of Mexicans are roughly one-third of those of Canadians (7:23 is the actual ratio for that period). And, if we use gross domestic product (GDP) per capita as a measure of relative affluence, Canadians are roughly three times more affluent than Mexicans. In short, Ehrlich’s formula holds: a small population of wealthier Canadians has a considerably higher impact on the environment (as measured in terms of GHG emissions) than the much larger but less affluent population of Mexico.
However – and this is a good ‘however’ – the per capita GHG emissions of Sweden for the same monitoring period (7.86t/person) were almost identical to those of Mexico. This does not conform to Ehrlich’s model, because Sweden has a slightly higher per capita GDP than Canada. And the usual, dubious excuses we use to explain away Canada’s high level of GHG emissions – we’re a cold climate, industrialized country, etc – no longer make sense, since the same things apply to Sweden. A more logical explanation is found in Ehrilch’s formulation itself:
- - it assumes that consumption levels automatically increase in lockstep with affluence, and
- - it is silent on the fact that technological improvements can lead to increased consumption, but they can also facilitate conservation.
As we become more affluent, whether it be as individuals or as larger groups of people, we have more economic freedom to make choices. We can choose to consume more, or we can choose to be modest in our consumption. We have a wider range of technologies to choose from as we become more affluent. Some technologies are inherently bad for the environment (disposable Tim Hortons cups and most Chrysler products spring to mind) while others are inherently beneficial (like bicycles and well-planned public transportation systems). When it comes to the environmental impacts of GHG emissions, evidently Swedes have made better choices than Canadians.
A discussion of the I = PAT model is therefore an extremely useful and clear way of introducing first-year students to two key themes of environmental studies: the need to find ways of decoupling consumption from affluence, and the continual need to innovate technologies that conserve and protect natural resources and ecosystem services. These are very hopeful messages that encourage students to think to the future in positive, yes-we-can terms. My students and I therefore go over this model every year, in the second lecture of the course.
The ecological footprint is something I find to be conceptually useful but ultimately very negative and discouraging. Conceptually it’s quite simple: a certain amount of productive space is needed to provide the resources necessary to meet each individual’s basic needs. But many of us consume well beyond what is needed to meet our basic needs (and by contrast, many people around the world have trouble even meeting their basic needs). Each one of us therefore has a different impact on the planet that can be measured in rough terms as the relative amount of productive space needed to support our individual lifestyle and corresponding resource consumption. This is our ‘ecological footprint’.
The researchers who developed the ecological footprint idea came up with a method of calculating an estimate of an individual’s footprint using a series of simple questions. I took the quiz at www.myfootprint.org recently. It was quite discouraging, for I learned that if everyone on Earth lived the way I do, we would need 3.6 Earths-worth of resources to support us all. Which is a physical impossibility, and means that my lifestyle is unsustainable and, in the long run, inherently damaging to the planet. Obviously I need to change my ways.
But which ones would I change? The house my family and I bought is a 20-year-old detached house. I suppose I could sell it and get a smaller one, like a semi or an apartment, but it would mean moving out of my neighbourhood entirely, for we own the smallest house for blocks around. We could replace our high-efficiency natural gas furnace with something else, but it would cost tens of thousands of dollars for a marginal improvement in terms of GHG emissions. The house is already fairly well insulated, but a few older windows could be replaced (and will be in due course). I already purchase offsets for my electrical consumption through Bullfrog power. As my students know, I commute most places by bicycle, even in the dead of winter. My spouse has a car, and needs one; she is a substitute teacher, and public transportation is so poor in Waterloo region there is no conceivable way she could get to work without one. I do not propose to ask her to give up her career simply to lower our ecological footprint a couple notches. I do take an average of two airplane trips a year for academic purposes, which I suppose I could cut out. My family and I do not eat out much, and we shop more than most people at local farmers’ markets, so there's not much I can do there to lessen my environmental impact.
My family and I have done most of the easy things we can do to minimize our impacts on the environment. Any further steps would be considerably disruptive, requiring abandonment of employment (not going to happen) or seeking out accommodations in a multi-family dwelling that is simultaneously accessible by foot to one of our places of employment and a year-round source of locally produced foods (am not sure such a place exists in Waterloo). Which made me wonder whether any Canadian’s lifestyle might get close to a 1.0 planets-needed score. So I took the same quiz imagining that I was alone, unemployed, living in a small downtown apartment, and eating the type of diet someone in that situation might eat. No car, no airplane holidays, no frills – just the bare essentials of existence. Kind of like a first year student. Guess what? My ecological footprint was almost exactly the same (3.69 Earths).
Obviously there is something inherently flawed in these ecological footprint quizzes. It would appear to be physically impossible for any Canadian to achieve a score of 1.0. So the question therefore becomes, why worry about it? If the only people who can have an ecological footprint of 1.0 are those who live hand-to-mouth in rural areas in developing countries, why should anyone care about conservation or sustainability? Quite frankly, I think it would be highly desirable it if everyone in the world lived a lifestyle comparable to mine. And if that means that over the short run we need the short term equivalent of 3+ Earths worth of resources to achieve, then so be it. There is nothing hopeful in the ecological footprint concept, and there is no useful purpose in getting my students all discouraged and gloomy about the future. The only message a student can take from the ecological footprint is that there isn’t much any of us here in Waterloo can do to reduce our environmental impacts in a meaningful way, so why bother? Since it occupies a significant amount of space in my students’ textbooks, I mention it in the first week, but I don't spend much time thereafter on the ecological footprint. If I can’t offer my students hope for the future, then I don’t want to teach.