Step On It! - Ecological Footprints
In The Picture
In purely material terms, our lives are defined by what we produce and what we consume. When we consume more than we produce, then our way of life becomes unsustainable.
The Earth, littered as it is with a number of resources, can absorb some of this over-consumption for a period of time. Unfortunately most of the Earth's resources are finite, meaning that there is only a certain amount of them. Once we use them up, that's it - once existing oil reserves run out, for example, we'll have to generate our energy in some other way.
This unsustainable way of life has even more serious repercussions from an ecological perspective. Our ravenous consumption levels are also taking their toll on ecosystems (think of rainforest deforestation, desertification in arid climates or depleted fish stocks) as well as the atmosphere (global warming and the thinning of the ozone layer being the two main examples).
As we've grown more aware of the problems unsustainable consumption levels bring with them, an analysis of how we consume resources has become far more detailed. Ecological footprints have become one of the most useful tools used to measure our consumption levels. This section explores ecological footprints, and then provides a tangible example of how a school can use them to raise awareness about ecological issues.
What is an Ecological Footprint?
Your ecological footprint measures the land and sea area needed to sustain your individual way of life. It calculates how demanding your consumption of food, goods, services, housing and energy is on the environment.
How does it work?
An ecological footprint compares the demands each individual places on the planet to the Earth's ecological capacity to regenerate its resources. It allows an individual to find out if, and by how much, their current consumption of the Earth's resources is unsustainable.
How is it measured?
Ecological footprints are expressed in "global hectares" or "global acres". When you divide the Earth's resource capacity by the global population, it is calculated that each person can use up 15.71 global hectares. If you take up more than that, then your way of life is biologically unsustainable.
An ecological footprint can be divided into four main categories:
- Goods and services
- Carbon (Fuel use, at home and transportation) - 6.77 global hectares
- Food - 7.13 global hectares
- Housing - 2.79 global hectares
- Goods and services - 6.78 global hectares
The total of all these four amounts to 23.47 global hectares per person. Remember, the Earth is only sustainable if each person uses up 15.71 global hectares. This means that, globally, our current way of life is overstretching the Earth's capacity by 50%.
Long Distance Dining from abroad to the UK
|Chicken from Thailand||10,691 miles by ship|
|Runner beans from Zambia||4912 miles by plane|
|Carrots from Spain||1000 miles by lorry|
|Potatoes from Italy||1521 miles by lorry|
Source: Rough Guide to Ethical Shopping (2004)
The exact quantity of feed required to make each kilogram of meat or fish varies between breed and farming method - and there are also great differences between the figures favoured by campaigners, on the one hand, and the meat industry, on the other. The following "middle of the road" estimates come from the non-partisan Council for Agricultural Science and Technology.
Kilos of feed required to produce 1 kilo of food
|Food||Kilos of feed|
Litres of water required to produce 1 kilo of food
The amount of water required to produce certain meats is also often very high (though naturally the relevance of this varies from country to country). According to a study by D. Pimentel, and published in Bioscience:
|Food||Litres of water|
Source: Rough Guide to Ethical Shopping (2004): 118