Do You Tread Lightly on the Earth?

An ecological footprint is a method for calculating your impact on the natural environment by assessing how much land is required to produce the natural resources that you use. We use these resources for food, clothes, housing, heat, transportation, education, and recreation. There are a number of interactive websites that calculate ecological footprints. They tend to give answers in terms of the area needed to sustain an individual, and the number of Earth-like planets needed to support humanity if everyone had the same lifestyle as the respondent.

Pre-Activity Questions:

  1. What is the definition of carrying capacity?
  2. Surface area of the earth: 510 million km2. Of that, land makes up about 149 million km2. If about 13.4 billion hectares (ha) are ecologically productive, what percentage of the Earth’s surface is biologically productive to a significant extent? (1 km2 = 100 ha)
  3. What is the current population of the Earth?
  4. What is the theoretical maximum for the average ecological footprint if the Earth is to be used sustainably (i.e. inhabited by humans into the indefinite future)?

Question: Can people live with lifestyles like ours indefinitely? What would a sustainable lifestyle for humans look like?

Hypothesis: Answer the question above in the form of your hypothesis.

Organize the data:

  1. Complete the table below as you work through three different ecological footprint sites. Some calculators are listed below, but feel free to search out your own sites instead.
  2. What is the size of the average Canadian’s footprint?
  3. What percentage of the average Canadian ecological footprint do you leave?

Questions / Footprint Calculator 1 / Footprint Calculator 2 / Footprint Calculator 3
URL of ecological calculator site
Name of the organization that sponsors the site
What is the size of your footprint (in hectares) using this calculator?
What questions were included in this survey, but not in the others?
How many planets would we need if everyone used the same amount of resources as you do?
Try survey #1 again, adjusting your answers to make it so that we would need one Earth if everyone used the same number of resources as you do. Were you able to achieve this? What did you have to change to do so?
Redo survey #2 as someone with your lifestyle in a tropical developing country (i.e. don’t change your answers to the questions, but pretend that you live in a tropical developing country). What was the ecological footprint for this scenario? How does it compare to your original footprint using this survey? Why does this happen?
Redo survey #3 a couple more times, drastically changing your answer to only one question each time. What seems to make the greatest difference in the final ecological footprint answer? Why do you think that had the greatest impact?

Post-Lab Questions:

  1. Scientific studies show that we currently use 40% of the net product of terrestrial photosynthesis and 25-35% of coastal shelf primary production, and that these might represent unsustainable use of ecosystems – for example, global fisheries yields have fallen for over 20 years. At the same time some global waste sinks seem full to overflowing. Half of the global population (3.5 billion people) lives on the equivalent of less than $2 per day. About 1 billion people live with a lifestyle comparable to Canada. Explain how these facts make it impossible to have all the people on Earth live with a lifestyle like ours.
  2. Why has every value for carrying capacity so far been an underestimate?
  3. What is the likely consequence of not resolving the problem of people exceeding their carrying capacity in the next 20 years?