Making our mark – ecological footprints
Key text
This topic is sponsored by Australian Government Department of Climate Change.
Ecological footprints are being used to measure our impact on Earth and the results aren't good.
We humans have been changing the face of our planet for thousands of years, clearing forests, damming rivers, draining swamps, ploughing the paddocks, building cities and freeways, creating the world we know. Our numbers have multiplied many times over; the living standards of many have increased beyond recognition. To make all that happen, we have drawn upon the Earth's natural resources such as air, fresh water and fertile soil.
We now know we are pushing our planet's resource base too hard if it is to support us long term. In many regions of our planet, the strain is showing; water is getting scarce, forests are disappearing, deserts are spreading and fish stocks collapsing. Our pattern of life, particularly in developed countries like Australia, has become unsustainable (Box 1: Sustaining our forests).
One way to measure our impact on Earth is to calculate how much of its limited surface area we need to provide our resources and to absorb the wastes we produce. The result of that calculation is our ecological footprint, which can be for an individual, a household, a city, a nation or for the whole human race.
We can then compare what we need with what the Earth can provide, its biocapacity. If we consume more than nature can supply for a long enough period of time, then a day of reckoning must come, as it did for some earlier civilizations. After all, if you consistently spend more than you earn, sooner or later you will go broke.
Why we need the land and water
Basic human needs have never changed; we need food and freshwater, we need shelter, we need clothing. Our needs have traditionally come from nature, and still do; fish from the sea, rivers and lakes, meat, milk, hides and wool from pasture land, cereals and fibres like cotton from cropland and timber from forests.
We need productive land and water to supply these resources. But we often build towns and cities on the land and prevent it being used for something else.
Land and sea ecosystems perform another vital task. They have the capacity to absorb carbon dioxide from the air, including our emissions from burning coal, oil and gas for the energy to power our modern lives. We produce other wastes: runoff from our towns and farms, solid wastes and gas emissions all affect the ecosystems around us.
How much land and sea we need to do all this is our ecological footprint. The planet's biocapacity is how much suitably productive land and sea there is available. Our ability to live sustainably (without the resource base collapsing catastrophically), depends on the balance between the two.
How much is there? How much do we need?
A report on the state of the Earth and the impact of human activities on it.
(WWF International)
Excluding the unproductive hot and cold deserts, our planet has about 11 billion hectares of land which are 'biologically productive'. If we divide that by our planet's current population of about 6.7 billion, about 1.6 global hectares is available for each of us.
But when we come to calculate what we need to live as we do, the answer comes out rather larger. Averaged across the planet, our footprint per person is about 2.2 global hectares. That suggests our planet is already oversubscribed and we are in trouble.
The average footprint hides wide diversity. For big-consuming nations like Australia, the footprint is 6 global hectares or more, while citizens of the poorest nations need less than a single global hectare. According to researchers at the University of Sydney, affluence has a major effect on the ecological footprint: the more we spend, the bigger the footprint.
The world-average ecological footprint hides wide diversity in the footprint of individual nations.
Biocapacity varies rather less. According to the Living Planet Report 2006, high-income countries average about 3.3 global hectares a head, but since they need more than six, each of their citizens is in the red ecologically by three hectares.
Poor countries need less but also have less. They are in the red too, but only by a tenth of a hectare. Middle income nations are more comfortable; indeed on the footprint/biocapacity balance, most are slightly in the black.
Bad news and good news
We now have data tracking what has happened to the human ecological footprint and to the biocapacity of our planet over almost half a century. The most interesting figures are those per capita, dividing the big numbers by the growing population of our planet.
Since 1961, biocapacity per head has gone down, as we would expect. The Earth has limited biological resources but a growing human population, so the share available to each of us must go down. And so it has, from around three global hectares in 1961 to less than two in 2003.
Yet the average human's ecological footprint has stayed much the same since around 1975. Even as many people have become richer and consumed more, the typical human is not stamping on the planet any harder. The total impact is greater because there are now more of us.
Contains a range of information on ecological footprints.
Looking more closely at the footprint, dividing it into sectors – cropland, forests, pasture, fishing and built-up areas – we find the total of those five components has declined. This is mostly because the cropland demand per person is down by nearly 50 per cent, the result of increased agricultural productivity.
Carbon's stamp
So with those declines, what has kept the footprint per person almost constant for more than 40 years? It is the emergence of the big one, the 'carbon footprint'. This is the amount of biologically-active land and sea that is needed to gather in the carbon dioxide we emit, mostly through burning fossil fuels for energy (Box 2: Tell me about carbon offsets).
Back in 1961, the carbon footprint per person was only 0.2 global hectares out of their total ecological footprint of around 1.5. Today, of the average 2.2 global hectares per person, absorbing the carbon dioxide would need one hectare by itself, nearly 50 per cent of the total footprint.
But there is some promising news. The total carbon footprint is growing more slowly now than it was 30 or 40 years ago, mostly as a consequence of the rising price of oil and the urgent need to make better use of it.
How many Earths?
So considering the available biologically-useful land and sea, how much of the Earth do we need to sustain us? In 1961, we managed quite well on the biocapacity of about 0.4 of the Earth. By 1980, that had risen to 0.9, largely from the rapidly growing carbon footprint. By around 1988, we needed it all. We had crossed the threshold, where our footprint exceeded biocapacity.
The figures suggest we now need about 1.2 Earths to survive. So how have we managed? We have allowed carbon dioxide emissions to build up in the atmosphere, since the biosphere cannot take them all in, and has not been able to do so for decades. That build-up brings the threat of climate change, so our reprise may be short-lived.
It could have been worse. Had the growth in carbon dioxide emissions not slowed we would now need the whole biocapacity of our planet just to deal with carbon dioxide. The crossing of the threshold would have come a decade before it did.
It follows that with the other demands on our planet's biocapacity declining (per capita), we now must concentrate on our carbon footprint. We have slowed its rate of growth once before. Now the need is more urgent; can we do it again? (Box 3: What difference can we make?).
Better analysis, worse news
The ecological footprint concept strikingly illustrates a brutal fact: our current lifestyle, assessed globally, is not sustainable. But it has its critics. Some see it as an oversimplification of complex issues. Others claim it has limited value to shape policies needed to build sustainability in particular regions, since it does not clearly show where the impacts are or how they can be reduced. Like GDP, another indicator that measures national income and output but is used to assess our standard of living, such assessments are open to a certain amount of criticism, but the key messages from them cannot be dismissed.
So the original idea is being improved by more sophisticated analyses. Scientists at the University of Sydney have developed a footprint that takes account of the whole life cycle of products and differences in land use. A US group, Redefining Progress, developed Ecological Footprint 2.0. This updated footprint model includes the biocapacity of the whole planet, rather than just the land, takes into account the needs of species other than humans and gives a more accurate estimate of the Earth's capacity to store carbon.
Both the per capita footprint and the per capita biocapacity are much higher using Ecological Footprint 2.0. But the takeaway message is the same. We are overtaxing the capacity of our planet to support us; in fact the shortfall (we need 1.4 Earths) is more severe than from the earlier footprint model.
Boxes
1. Sustaining our forests
2. Tell me about carbon offsets
3. What difference can we make?
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Feeding the future – sustainable agriculture
Carbon currency – the credits and debits of carbon emissions trading
Enhanced greenhouse effect – a hot international issue
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Posted December 2008.