Q: I have often heard questions about assessing the environmental impact of A versus B answered with a common metric in order to compare apples to apples. The metrics are usually in quantity of carbon released or in dollars. Is there a more sophisticated environmental impact index out there that encompasses multiple metrics at once?
Asked by Jana Watson-Capps, '99, Longmount, Colo.
We tend to fixate on one environmental problem at a time. In the 1960s, it was pollution, typified by Rachel Carson's Silent Spring. In the 1980s, the world turned its attention to the hole in the ozone layer. Today, climate change is the immediate issue that comes to mind. But measuring climate change's culprit—carbon emissions—can't possibly tell the entire impact of a proposed project. Our Essential Answer presented one alternative to a purely carbon-based approach, but there are several others also worth discussing.
Life Cycle Assessment: A holistic point of view
A widely-used analysis method is the life cycle assessment (LCA) approach, which follows a product's, well, life, from "cradle to grave." In other words, LCA calculates the impact of a product from its initial creation all the way to its disposal or recycling. Like ecological footprint analyses, LCAs are useful because they take into account all of the input and outputs of a process, not merely its cost or associated carbon emissions. While ecological footprint analysis always produces an output of land area, LCAs might produce a different type of result for each unique project. To see how, let's look at the way LCAs are structured, using a land use example. Imagine that you are a land developer weighing the pros and cons of two development trajectories: creating a large, commercial farm, or a small, community-managed set of plots. LCA can help us sort out the impacts. We will use four stages in our LCA approach, adapted from the World Resource Foundation: goal and scope, life cycle inventory, impact analysis and improvement analysis, which are outlined in Figure 1.
| Stage | Tasks |
|---|---|
| Goal and Scope | "What are we trying to accomplish? What data do we want to collect?" "How should we organize and display that data?" |
| Life Cycle Inventory | Collect data Quantify energy and resource inputs |
| Impact Analysis | "Will the farm's irrigation systems negatively affect biodiversity in the region?" "To what extent does agricultural fertilizer run-off from the farm have adverse effects on human health?" |
| Improvement Analysis | "What improvements can we make to this process, that would benefit all the stakeholders?" |
After completing the four-stage process for the commercial farm, we would do the same for the community-owned plots to return a similar unit for comparison. Comparing them directly enables us to make a more informed decision about which type of farm has a lesser environmental impact, for a given amount of food produced.
In many circumstances, however, the "better" option isn't the more popular. For example, a big commercial farm might be more efficient and even more environmentally friendly, but many citizens would still prefer to have a community-owned farm for other reasons. Or the commercial farm might be more polluting, but provide more jobs. This is the type of issue that the analysis method known as agroecosystem analysis attempts to reconcile.
Agroecosystem analysis: Sure, we care about the Earth, but what about us?
Agroecosystem analysis, like LCA, is a framework used to discuss environmental impact. The primary difference between the two analyses, then, is agroecosystem's relative emphasis on people, in addition to environment. Gordon Conway, professor of international development at Imperial College, pioneered agroecosystem analysis in a book; dividing it into the four categories of productivity, stability, sustainability and equitability.
Productivity is a measure of net product per unit of resource, whether land, energy or financial capital. It answers the simple question, "how much does this system produce compared to my inputs?"
Stability is the resilience of a system in the face of small environmental changes. For example, if the average temperature this year was half a degree less than normal, will I see a small or large reduction in yields?
Sustainability is similar to stability, but measures a system's ability to maintain yields in the long term, even after large disturbances or extended stresses. If a huge flood hit our farm, would it be able to bounce back to its normal productivity the next year? Or would the system be irreversibly damaged by that disturbance?
The last part of agroecosystem analysis is equitability. This is where the model diverges from the footprint or LCA approaches. In Conway's words, equitability measures, "how evenly the productivity of the agroecosystem is distributed among its human beneficiaries. The more equitable the system, the more evenly are the agricultural products, the food or the income or the resources, shared among the population of the farm, village, region or nation." In this way, agroecosystem analysis accounts for the "social fairness" of a system.
A Return to Ecological Footprint
Finally, let's return to the method outlined in our Essential Answer: ecological footprint analysis. While useful in assessing local issues, these methods aren't limited to the smaller-scale projects to which we've been applying them. Take a look at Figure 2 from the 2006 WWF Living Planet Report, which compares ecological footprints of different countries to their Human Development Index (HDI) number, a metric that incorporates educational, health and economic indicators to assess a population's standard of living. This chart essentially visualizes the link between human well-being and environmental impact. As you can see, there is one country that has both a sustainable footprint and high HDI number: Cuba. Methods like ecological footprint analysis allow us to make powerful statements about the impact of our species on the planet, and how tightly connected that impact is to standard of living. For now.
So which is the best?
Why even use these complicated analytic tools? In your question you raised a strong argument for them: that "carbon released" is often the sole metric used to measure environmental impact. Like you, Professor Naylor takes issue with this. As an example, she discusses the issue of feedlot-raised compared to grass-fed cattle. Some groups, including the Food and Agriculture Organization of the United Nations, have concluded that raising cattle in feedlots is less carbon intensive, and thus better for the environment. But, says Naylor, "what about all the other environmental impacts? What about the nutrient pollution that comes from these kind of intensive operations? What about the smell? What about the pesticide and hormone use? You could go on to all these other things." "All these other things" begin to be accounted for when using the analysis methods we've been discussing.
Ecological footprint analysis, life cycle assessment and agroecosystem analysis all attempt to evaluate our human practices and reduce our impact on the planet. Choosing the right one for the situation can be tricky, but here are a few suggestions: Do you need to carefully craft a piece of legislation? Conduct a comprehensive LCA or agroecosystem analysis. Do you need convince a skeptical public? Tell them how much carbon they're spewing or how big their footprint is. Do you want to figure out your personal impact so you can start to lower it? Start with the five-minute quiz.
Above all, Naylor offers perhaps the most important piece of advice: "Keep it simple," she says, "but keep it relevant."
