The Footprint Concept
The ecological footprint has become a valuable global instrument for representing human sustainability.
It is an estimate of the space on the planet that is needed to keep each human living the way they currently live.
An individual’s footprint is the area of biologically active land and water area that is required to produce the food they eat, the water they drink, the air they breathe, and to manage the waste they produce.
People in different parts of the world live very differently and have very differently sized footprints.
Every Australian has an average ecological footprint estimated on the basis of 2003 data at 6.4 global hectares (or 64,000 square metres). A global hectare is a hectare that is “normalized” to have the average biological productivity of all of the world’s biologically productive land and water in a given year.
In other words, to live the lifestyle that we currently lead in Australia, each of us on average uses at least 6.4 soccer fields of biologically active land and water.
For the 955 million people who live in high income countries the average footprint is about the same as ours although there is a substantial range of average footprints across these affluent countries); for the 3.1 billion people living in middle income countries it is 1.9 hectares and for the 2.3 billion living in low income countries it is 0.8 hectares per person.
During the period that the available biologically active land has been declining in recent decades, the human global footprint has been increasing and human numbers are also increasing by about 80 million humans per year.
The planet is already stressed because collectively we are already asking more from it than it can manage in a sustainable way. At the same time, developing countries are increasing the size of their per capita footprints as their economies develop and as their consumption aspirations grow.
Humanity’s Ecological Footprint is spread across six land use categories; crop land, grazing land, fishing grounds, forest, built up area and land for carbon absorption.
The latter is about half of the total and CO2 production is responsible for about half of humanity’s ecological footprint In 2003, there were approximately 11.2 billion global hectares of biologically active land and water available and in that year humanity demanded products and services from the equivalent of 14.1 billion global hectares.
Issues and Trends
Estimates of national and regional ecological footprints are derived from national and regional census and household expenditure analyses.
The methodology for doing this at a national and international level is agreed upon by an international Global Footprint Network and standardization of the methodology is progressively being achieved, though there are two different and not yet fully reconciled schools of thought. Ecological Footprint Issues and Trends is available for download.
Because the science of footprint estimation is still evolving, a range of different calculators are available for assessing an individual’s per capita footprint by asking them a series of simple questions about their lifestyle choices which are used to modify the estimate of the average footprint that is computed in the conventional way for all of the residents of their region.
Because the individual calculators weight different behaviours in different ways, they can produce different individual footprint estimates.
The product of an individual calculator is a relatively crude approximation. But it has educative and motivational value and various calculators are widely accessible on the web.
The national and regional computations which are based upon statistical analysis of large sample national household expenditure and full sample census data are more dependable than estimates for small populations and groups and individuals.
The footprints published in the recent ACF Consumption Atlas are derived from the periodic National Household Expenditure survey (for which nearly 300 randomly chosen households contributed the Canberra data) and the suburb estimates are derived by a regression approach which modifies the Canberra-wide data by the census-derived demographic profile of the suburb.
Because we live in a highly energy dependent society most of the products we purchase, have within them, “embedded energy” that has been expended in their production, packaging, or transportation. At present. most of this energy is generated by the combustion of fossil fuels resulting in the release of CO2.
Recent estimates indicate that the CO2 emissions that are generated by the average Australian householder are derived 28.3% from food, 29.4 per cent from goods and services, 20% from household electricity, gas and firewood,10.5% from travel (petrol, public transport and air travel), and 11.8% from construction and renovations.
The full ecological footprint is even more heavily dominated by food choices with 48.8% of the footprint being derived from food, 35.1% from goods and services,7% from use of household electricity, gas and firewood, 3.2% from travel (petrol, public transport and air travel) and 5.9% construction and renovations. The Consuming Australia atlas is available for download.
It will be apparent from this brief description that any attempt to reduce the ecological footprint and the average carbon emissions generated by Australia households will need to pay particular attention to the issue of food choice and should include encouragement for Australian families to return to increased domestic food growth and production.