Think of the ways you teach pupils about our ecological impact on the earth. Depending on their ages, you probably show videos of ecological destruction such as devastated rainforests and spreading deserts overseas. You may lead trips to explore relevant local issues such as a proposal to create an out-of-town superstore on a nature reserve or road building through a meadow. And you might invite environmentalists in to lead a class discussion.
Although these methods are useful, they have three major drawbacks. First, they provide only examples of human impacts on ecosystems, not a model through which impacts can be easily visualised. Second, they don't measure an individual's impact, so fail to personalise them. And third, they often fail to show the connection between local and global issues.
All this is about to change. A simple model developed in Canada calculates the ecological impacts of our lifestyles in terms of the land area needed to support it. It helps pupils visualise their local and global ecological impacts and understand their own role in them. Developed for planners, but of obvious benefit to teachers, the "ecological footprint" is a measure of the load imposed by an individual on the environment.
The footprint area represents the amount of land and water needed to supply our resource inputs (fossil energy, built-up land, land used to provide food, clothing and timber), and absorb our outputs (human wastes, pollution and carbon dioxide). In other words, a footprint is the total ecosystem area "appropriated" to support an individual at a given level of consumption and waste production. The footprint calculation is complex and time-consuming, but it is explained in detail by its originators, Mathis Wackernagel and William Rees, in their book, Our Ecological Footprint.
But the appeal of the footprint model is that it offers a simple, yet graphic, mental image of individual ecological impact, and it is reasonable to assume children's footprints correspond largely to those of their parents. A footprint is not fixed - it depends on parental income, personal decisions and values, use of technology and other factors. With this in mind, Year 6 pupils at Winton School, north London, have been investigating footprints.
Deputy head Clair Butler says: "The children have little appreciation of the impact of their consumption." She started by getting them to look at the food they ate in a day, where it came from, and how it found its way to the table. "The footprint concept was soon grasped," says Ms Butler. "They began to build a picture of how 3.5 hectares (ha), the average individual footprint in the United Kingdom, is used up." The pupils are now developing a playground footprint - a scale imprint of the average footprint in the UK, India and the United States. Their next challenge is to investigate ways of treading more lightly.
The beauty of footprints is that they can be applied at a variety of scales, from the individual, to a school, a city or a nation. They can even be used to identify more friendly options, such as less damaging forms of travel.
Footprints can be used to highlight ecological and material inequities between nations. For instance, a person from the United States has an average footprint of 5.1ha, from Canada 4.3ha, from south-east Queensland in Australia 3. 74ha, from the UK 3.5ha, and from India 0.4ha. The world average is 1.8ha.
On the city scale, London's ecological footprint is 125 times the area of the city itself, some 19,755,600ha. The total surface area of Britain is only slightly greater at 24,240,000ha. At the national scale, the Netherlands, a small but densely populated country, has an area of 3,392,000ha. Its footprint, at 49,800,000ha, is 15 times larger than the country itself, and twice the size of Britain, Next time you commute, consider the following. The footprint of one person travelling 10km a day on a bike is 0.012ha; by bus it is 0.030ha and alone in a car it is 0.153ha. The cyclist footprint represents land for extra food consumed, but the bus and car user footprint represents the land needed to absorb carbon dioxide produced by combustion.
The impact of our individual footprint is not only local, just as London's 125 x footprint doesn't fall only in the London area, or even in Britain. We leave our footprint wherever in the world we obtain our resources and deposit our wastes.
Footprinting is still in its infancy. At Winton, it is helping in the delivery of key stage 2 standard coursework in maths, English, science, history and geography. At KS3 it could provide a focus for work on sustainable development. Footprint analysis shows that: * wealthy nations appropriate ecological and material wealth from around the planet, that is, they are in ecological deficit * cities, where increasing numbers of the world's population live, are not sustainable * the large size of individual footprints in wealthy nations is largely due to high levels of fossil fuel consumption.
Ecological footprinting has the potential to communicate to a wide range of audiences. It could become the model against which pupils, teachers and the public realise their present size 11 lifestyle is not sustainable and that it is time to change.
Our Ecological Footprint, by Mathis Wackernagel and William Rees, published by New Catalyst Press, Canada, can be obtained from Jon Carpenter Publishing, The Spendlove Centre, Charlbury, Oxfordshire OX7 3PQ, tel: 01608 811969, Pounds 11.99 paperback Julian Agyeman is a consultant in environmental and sustainable solutions. With Bill Lucas he is producing a pupil resource on ecological footprints, due out in spring 1998