Ecological Footprints and Sustainability
This assignment allows the student to calculate his or her own "ecological footprint" and see how the footprint concept relates to sustainability.
INTRODUCTION
Like all species, humans need certain resources to survive. However, humans consume resources not only for survival, but also for comfort, luxury, and prestige. Whereas non-human species generally must obtain their resources from within their ecosystem, in contrast, humans have devised ways (transportation) to remove resources from other ecosystems to satisfy their wants and desires. However, societies are not equal in their ability to extract, transport, process, manufacture, and use resources. And, societies have different philosophies and cultural perspectives regarding their desire to utilize resources beyond basic needs. Thus, there is a question of equitable distribution of resources among human societies and between humans and other species.
In addition to resource extraction, an additional crucial ecosystem function is the assimilation of waste, sometime, known as sinks (e.g., air, water, and soil pollution; hazardous, solid, and radioactive waste; and waste heat). Again, humans have devised ways to discharge wastes into other ecosystems by building tall smoke stacks, dumping waste in flowing rivers and oceans, and shipping "recyclables" and wastes around the globe.
The area of productive land required to provide resources and assimilate waste to meet consumption needs is referred to as the Ecological Footprint (Wackernagel and Rees, 1996). This is different from carrying capacity which is the maximum abundance of a population that can be sustained by a habitat or ecosystem without degrading the habitat or ecosystem. Because non-humans cannot extract resources from outside of their ecosystem, their population cannot exceed the carrying capacity, which is based on the availability and amount of an ecosystem's resources. Thus, a non-human's ecological footprint is limited by the size of the ecosystem. In contrast, humans also have a carrying capacity for their "ecosystem" (for example, a country). However, because humans can transfer resources from another country, their ecological footprint can exceed the carrying capacity.
Thus, the U.S.'s ecological footprint can exceed the carrying capacity of the U.S. (i.e., the U.S. can maintain more people than available resources) because resources are extracted from Mexico, Africa, Saudi Arabia, and so forth. Clearly, this means that for some countries, their ecological footprint must be smaller than the carrying capacity because the Earth is finite. Or, some populations must live near the subsistence level, whereas other can live in high comfort. A method to determine and compare this is to calculateand compare the per capita amount of resource use (the amount available/consumed on a per person basis). Calculating the per capita is done by dividing the amount of available biological resources and waste assimilation needs by the population (resource / population).
The ecological footprint is one measure of the sustainability of a society's current lifestyle. However, this is an anthropocentric view. If humans consume all the resources or take over all the biologically productive land, what about non-humans? And what about humans in less developed countries? This is an issue of environmental equity. As shown in Figure P8.l, the average per-person ecological footprint in the U.S. is nearly 10 times greater than the per-person ecological footprint of India.
Figure P8.1—Comparison of Ecological Footprints Between India and the United States.
In developing nations such as India, about one hectare is needed to meet the resource requirements of an average person. In the U.S., the average individual ecological footprint is almost ten hectares. If everyone in the world consumed resources equal to the average American, we would need five Earths. Source: Raven, P.H. and L.R. Berg. 2004. Environment. 4th ed. John Wiley & Sons, NY (p. 189).
TASKS
In this lab, you will individually analyze your consumption and life activity patterns to calculate your ecological footprint using an Internet-based ecological footprint calculator. Please do the following tasks and answer the following questions:
1. Go to the U.S. Census Bureau's population calculator at
a. What is the current world population? (Note the precise local time—for example, Eastern Standard Time—you determined this.)
b. What is the current world person/hour growth rate?
c. What is the current U.S. population? (Note the precise local time you determined this.)
d. What is the current U.S. person/hour growth rate?
2. Go to or a site provided by your instructor. Answer all questions on
the website truthfully. If you are not sure of the answer, make an educated guess.
a. What is your ecological footprint in acres? in hectares?
b. How does your footprint compare to the average American footprint? (Compare quantitatively as in percent difference.)
c. If everyone in the world had the same footprint as you, how many Earths would be required to support the global population?
3. If you are using click on the button "What About Other Species."
The Bruntland Report states that 12% of the biosphere should be set aside for other organisms.
a. By using 12%, what answer do you get for the number of Earths required?
b. Do you think this amount (12%) should be higher or lower? Explain why.
c. Assume that you believe that 25% of the Earth's resources should be set aside for non-humans. Now
what is your answer?
4. Go outside to a field or parking lot indicated by your instructor. Using a measuring tape, calculate the area (in acres and hectares) of the field.
a. How many acres are contained in the field? how many hectares?
b. Based on your ecological footprint answer from Question 2.a., how many of these fields would be required to support your ecological footprint?
c. What percentage of your campus would have to be devoted to supporting your life? What is your source?
5. The Earth's biosphere currently has an estimated 26.7 billion acres of biologically productive land.
a. Now what is the world's current population? Use the U.S. Census Bureau's population calculator at
b. At what precise local time did you determine this?
c. How many people have been added since you first checked?
d. Based on available biologically productive land and the current world population, what is the global per
capita amount of biologically productive land? (Show your work.)
6. A key component to sustainability is population growth. Thus, it is important to estimate future population growth to assess its sustainability. One measure of future population is to estimate a population's doubling time, which is based on the current, annual percentage population growth rate. This is the so-called rule of 70, a rudimentary estimate. Divide 70 by the percentage of growth and you will obtain the doubling time. (For example, if growth is 2%, then 70/2 = 35 years.)
a. According to the U.S. Census Bureau, in 2003, the annual U.S. population increase was l.01%.
Assuming steady growth, in what year will the population of the U.S. double?
b. Approximately how many people will live in the U.S. on that date?
c. In 2002, the annual population growth rate for Mexico was 1.47%. Assuming steady growth, in what
year will the population of Mexico double?
d. What will the population in Mexico be on that date?
e. What are the environmental implications of the doubling of population for Mexico and the U.S.?
7. What about equity? Is the U.S. ecological footprint fair and equitable compared to that of other countries? We will assume that the U.S. has 293.7 million acres of biologically productive land and that the average American needs 24 acres to maintain his/her current lifestyle. Now, go back to the U.S. Census Bureau's population calculator at
a. What is the current U.S. population?
b. What is the precise local time you determined this?
c. How many people have been added since you first checked?
d. Is there enough biologically productive land in the U.S. for current consumption habits?
e. If not, where, specifically, do Americans obtain their resources?
f. What happens to the humans and non-humans living in those ecosystems?
g. What is the current world population? h. What time did you determine this?
I. How many people have been added since you first checked?
]. Recalculate the per capita availability of global resources (i.e., resources divided by population).
k. Is the amount of global biologically productive land increasing, staying steady, or decreasing?
I. What are the ramifications of your answer based on the increasing population?
8. Assume steady growth, consumption rates, and size of the average ecological footprint for the U.S. Answer the following questions using some of the numbers you obtained in your answers. Explain the significance of population growth in relation to:
a. Ecological resources
b. Waste assimilation
c. Sustainability
d. Equity
9. Evaluate the ecological footprint calculator you used for this assignment. Do you think the footprint is accurate, why or why not? What could be done to improve the accuracy of the ecological footprint calculator?
Reference
Wackernagel, M. and W. Rees. 1996, Our Ecological Footprint: Reducing Human Impact on the Earth, New Society Publishers, British Columbia, Canada.