Using Ecological Footprints to Teach Sustainability

Technically- and traditionally-speaking, an ecology course should not really deal too much with policy. A strict definition of ecology should limit the topic to the study of the interaction between organisms and their environment, and for decades now that has meant looking at how non-human animals and other organisms constitute ecosystems. Discussions of policy, economics, culture and others facets of the “human side of the living world” were left for courses in the more synthetic discipline of environmental science.

I agree in part with this separation: in some sense, ecology ought to be the somewhat-pure study of the organismal component of our “living environment”. Ecologists understand this living component of our world, and it is too much to ask these same ecologists to also be experts in other broad disciplines related to human culture and industry. For this reason, the best environmental science departments in the world are composed of interdisciplinary teams of biologists, economists, earth scientists, ethicists, chemists, philosophers, sociologists, political scientists, psychologists, law scholars, and engineers. To truly tackle our vast environmental problems, many experts must sit at the table.

Increasingly, however, ecologists are getting more comfortable in the world of human culture and industry. This is a big shift from the past, where ecology was mostly the study of organisms in pristine environments. Fifty years ago, it was possible to ask how an ecosystem operates in the absence of human influence and get an answer through intensive investigation in some remote location. Today, it is nearly impossible to answer this same question anywhere on the earth, as the influence of human actions reaches nearly every ecosystem in some way. Forced by necessity to consider how human activities affect ecological interactions, ecologists have begun to integrate other disciplines into their study habits.

My course in Ecology reflects this integration. I can still defend it as an ecology class (and not quite an environmental science class, although it flirts with this boundary), but I have thoroughly included the human species and all of its ecological impacts into my course. We spend the first half of the course learning basic principles that explain ecosystem functioning, and then spend the second half looking at how human activities threaten to disrupt this functioning. Although we sometimes think about what kinds of actions might be necessary to prevent catastrophic disruption of ecosystem functioning, we mostly stay on the “ecology” side of these political and economic issues. Given that I only teach non-majors, I feel completely comfortable in this arrangement of the course: it is far more important that my students understand the basics of how human actions threaten the basic functioning of ecosystems than learn the minute details of ecosystem functioning.

My biggest foray into the human world comes in the final two lessons of the course, which are dedicated to the topic of sustainability. Sustainability is a big focus at Pratt, although the meaning of the word is not consistently defined across the campus. I try to get my students to see the antiparallel between the sustainability of natural cycles found in ecosystems and the unsustainable nature of human industry. This comparison is made more clear by the fact that much of human industry acts as a threat to the natural cycles which provide us with the many ecosystem services that sustain us.

A large part of making human activities more “sustainable” is to make changes to our technologies; these changes generally require changes to both policy and economics. I spend the whole of my last lesson discussing the myriad possible technologies which might make our activities as a species more sustainable. But before I discuss all of these technologies, I want to make sure that my students understand why our current practices are unsustainable. In looking at why we cannot continue on our current path, I try to get my students to look at both the material and social components of unsustainable societies: this is the focus of my introductory lesson in sustainability.

The best way to understand how unsustainable most of our lifestyles are is to consider how everyday activities impact our ecosystems. Ecological footprinting represents the most direct and easy way to make this point. An “ecological footprint” is a way of expressing how everyday actions (most of which involve consumption of one form or another) translate into an overall impact on ecological systems. There are a number of different ways of measuring an ecological footprint, as the metric of “impact” can vary, but many ecological footprint calculators express impact as a fraction of land area.

Over the past four years, I have used a flash-based footprint calculator called “Consumer Consequences” to help my students understand the concept of sustainability. A week before our first lesson in sustainability, I ask each of my students to complete the following questions using the Consumer Consequences calculator:

1. Complete all parts of the survey based on your current lifestyle. How many earths would your lifestyle require if everyone lived the way you do?
2. Based on the summary of your activities, what single change in your lifestyle would cause the greatest reduction in the amount of land your lifestyle requires?
3. Describe how your lifestyle would have to change in order to reduce your impact level to “1.0 Earths”?
4. Now complete the survey based on the lifestyle of your parents/guardians or a close relative who is about a generation older than you. How many earths would their lifestyle require if everyone lived the way they do?
5. Based on the summary of your relative’s activities, what single change in their lifestyle would cause the greatest reduction in the amount of land their lifestyle requires?
6. Describe how their lifestyle would have to change in order to reduce their impact level to “1.0 Earths”?
7. What are some of the flaws of this survey and the data it provides? What could be incorporated into the survey to correct these flaws?

Each student reports their results via the course’s Learning Management System. This makes their results visible to me, but to encourage honesty in reporting I try to make it clear that neither their grade for the assignment nor my impression of them will be affected by what they report. For the most part it appears to me that students fill out the survey questions and calculate their footprint honestly, although I have no true way of being sure of this.

Consumer Consequences uses acreage to determine the impact of each person’s activities. This can be slightly confusing to students at first, but figuring out how this conversion works helps reinforce concepts covered earlier in the class. For instance, students often wonder why flying in airplanes “costs” so many acres. This opens up an opportunity to discuss the large amount of fossil fuel needed to keep an airplane aloft during flight and to connect the resulting greenhouse gas emissions to the number of acres of unimpacted forest or ocean needed to sequester all that carbon. The end result that students get is valuable: the Consumer Consequences calculator reports how many earths it would take to support the earth’s human population if everyone lived a lifestyle similar to that of the student.

Before this first lesson in sustainability, I compile all of the student reports (anonymized, of course) to determine a classwide average and distribution [if you want to do the same calculations, you can use this spreadsheet for your class]. The results are always disturbing. Generally, no one living in a developed economy is going to clock in at less than one earth, which would indicate a “sustainable lifestyle”. Primarily this is due to the fact that we have such unsustainable lifestyle choices; in smaller part the Consumer Consequences survey is somewhat “rigged” to prevent the user from being sustainable, which I will discuss further below.

What is miraculous to me is how consistent the results have been over the past five semesters that I have done this activity. For each semester, based on approximately thirty responses per semester, here are the results I have gathered:

I have not done any formal tests of significance on these data, but it is striking how consistent the results are from year-to-year. My students, who live in a city with abundant rapid transit and very efficient housing, consistently clock in at around 3.5 earths. Their parents and other older relatives clock in at around 5.1 earths. Based on the results of the survey, students report that food choices (type of food, local versus imported, organic versus conventional) represent that largest proportion of their impact, with some students (particularly those who fly internationally to visit family) also showing a large transportation impact. Typically their parents carry extra impact due to living in larger homes, driving more, and having to travel via air for work. Although generally the impact of students is lower than that of their parents, there are some cases where parents have a lower impact.

Although I have tried to word the questions for this assignment in as neutral a fashion as possible, a number of my students are quite defensive once they have seen how many earths their lifestyle requires. I try to be sympathetic to these concerns as I provide feedback on their answers. In class we discuss these results, and generally the students shift from being somewhat defensive to being more proactive in their thinking about how to reduce their impact. We discuss how hard it is to live in an industrialized society and maintain a low-impact lifestyle. I explain how I ride a bike as my primary means of transportation, use electricity from a renewable source, and eat vegan, but still maintain an impact requiring 2.8 earths: because I eat a lot of food that is not local and fly for work and vacation, I too have a lot of room for improvement. This allows us to get into a more detailed discussion of how the choices of individuals are highly-constrained by the choices made available in the society at large. Having seen how large their impacts are, many students clamor for better alternatives. The Consumer Consequences interface actually gives you the chance to consider how government regulations requiring greater efficiency would impact your score, which also reinforces the message that individual choices alone are not sufficient to lead to a sustainable society.

One of the things that always comes up in our discussion of our results is the question “if we are not living sustainably, how is it that the earth’s ecosystems have not collapsed?”. This leads to two important observations. The first is that luckily not everyone on the earth lives the way that we do. Poorer people living in less developed countries lower our overall impact by virtue of being impoverished. Students begin to appreciate the tension between poverty, development, and sustainability, which allows me to talk about the Millennium Development Goals of the United Nations’ Organisation for Economic Co-operation and Development. The second observation is that although we are currently living in an unsustainable manner, we may not be paying an immediate price for the damage we are doing. To provide context for this concept, I also assign my students to read the Nature article “A safe operating space for humanity” (Rockström et al. 2009), which discusses thresholds for various forms of human impact. Taking into account the delayed nature of many impacts, we can discuss the issues of inter-generational equity raised by our current lifestyles.

Because I ask students to critique the Consumer Consequences interface, I get to hear a lot of their frustrations and concerns. Many students note that their lifestyles could not be adequately represented by the survey, which constrains choices in ways that sometimes distort the lifestyle habits of an urbanite. This allows us to discuss what facets of the survey could be more precise and what the benefits and costs of that added precision are: in particular, as designers my students must consider “usability” tradeoffs associated with asking more detail from survey participants.

Interestingly, a second set of complaints is aimed not at the survey precision but at the judgments it seems to level. Some students express concern that they or their parents should not be penalized for their lifestyle because they live in places without alternative transportation, or because they are too poor to buy local and organic food, or because of some other often-understandable excuse. This reaction is interesting, because it is clear that students are already translating an objective measure (after all, impact is impact regardless of whether it can be helped) into subjective, normative terms. They want the calculator to give them a break, to consider their individual needs and rationales, which of course probably applies to everyone’s choices. Although it sometimes takes some time to explain that the inanimate footprint calculator is not leveling judgment, these student reactions are productive because they lead to a broader discussion of what would allow individuals to make more sustainable choices.

Following this discussion of sustainability and the role of individual choices, I have my students do my Evolution of Sustainable Use activity, which further challenges them to think about how to harness collective action to prevent unsustainable exploitation of ecological resources.

Overall I have had good success with the Consumer Consequences activity, although it lacks a really clear explanation of how it makes its calculations and sometimes seems to be producing unintuitive results. There are FAQ’s that address vaguely how the calculator works, and if you want to know more you can go on Redefining Progress’ more elaborate footprint calculator, which also maintains an FAQ and allows you to post a link to your results. To show that I still have some work to do, here are my results.