ES1B1 - Problem sheet - Ecological footprints

ES1B1 Introduction to Environmental Science

Ecological footprints

Like all species, humans need certain resources to survive. However, humans consume resources not

only for survival, not 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,

sometimes 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 to 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, M. and Rees, W. (1996) Our ecological

footprint: reducing human impact on the earth. New Society Publishers, British Columbia, Canada).

This is different from carrying capacity which is the maximum abundance of a population that can be

sustained by a habitat or 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 UK’s ecological footprint can exceed the carrying capacity of the UK (i.e. the UK can maintain

more people than available resources) because resources are extracted from Africa, the Middle East, etc.

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

others can live in high comfort. A method to determine and compare this is to calculate and 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 divided by 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, for example, the average per-person ecological footprint in the US is

nearly 10 times greater than the per-person ecological footprint of India.

Questions

Spend 10 minutes on questions 1 and 2 and be prepared to feedback to the class.

The aim of this practical is to calculate your ecological footprint.

1. Go to the US Census Bureau’s population calculator at

/main/www/popclock.html

a. What is the current world population (note the precise local time)?

b. What is the current world person per hour growth rate?

c. What is the current US population (note the precise local time)?

d. What is the current US person per hour growth rate?

e. What is the current China population (note the precise local time)?

f. What is the current China person per hour growth rate?

2. Go to /

If you are not sure of any of the answers make an educated guess.

a. What is your ecological footprint in acres and hectares (1 acre = 0.4047 hectares, 1 hectare =

2.47 acres)?

b. How does your footprint compare to the average footprint of the country that you are looking at?

(Compare quantitatively – calculate a % difference)?

c. If everyone in the world had the same ecological footprint as you, how many Earth’s would be

required to support the global population?

Spend another 5 minutes on Q3.

3. What about other species? The Bruntland Report states that 12 % of the biosphere should be set aside

for other organisms.

a. By setting aside 12 % of the planet for other species what answer do you get now for the number

of Earth’s required to support the human population?

b. Do you think this amount (12 %) should be higher or lower, why?

c. Assume that you believe that 25 % of the Earth’s resources should be set aside for non-humans.