Making our mark – ecological footprints

Key text

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?

Related site: Living planet report 2006 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.

Related site: Global Footprint Network 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.

Related Nova topics:

Population and environment – what's the connection?

Feeding the future – sustainable agriculture

Carbon currency – the credits and debits of carbon emissions trading

Enhanced greenhouse effect – a hot international issue

Capturing the greenhouse gang

Box 1: Sustaining our forests

Ecological footprint calculations show that Australia exploited roughly 0.5 global hectare of forest per person in 2003, making up 8 per cent of our total footprint. Australian forests are harvested for timber and woodchips, with a large proportion of woodchips coming from native forests for export to countries like Japan. Most nations use less (the global average is only 0.17 global hectares), but a few (the USA, Canada, Sweden and Finland) need more because their forest industries are bigger. Like Australia, many nations harvest their forests for export to other countries.

In terms of forest biocapacity we do quite well, with more than three global hectares available per person (again well above the global average of less than one). Much of that is held in national parks and other reserves and so is not available for exploitation, though the forests provide other vital ecological services, protecting biodiversity, soil and water quality, storing carbon and providing somewhere to get away from it all. The area of plantation forests is increasing in Australia, although they can actually reduce biodiversity depending on whether they are planted on former native forest land or farming land.

Since European settlement, a quarter of our native forests and woodlands have gone, replaced by farms and settlements. We hear most about the loss of rainforests, a third of which have vanished, though they make up only 3 per cent of Australia's forest resources.

Agriculture is the major driver of land clearance, and that has a big impact on the vital task of controlling carbon dioxide levels in the air. Land clearing releases carbon dioxide into the atmosphere, as the fallen trees are burnt or allowed to rot, and the crops that replace them are usually not as good at storing carbon.

Fortunately, there is some good news. There is less land clearing now, and carbon dioxide emissions from forest related activities dropped by 74 per cent between 1990 and 2005. The biggest improvement has been in Queensland, the major contributor (mostly due to land clearing) in Australia. Stronger government policy has helped to maintain native forests while still supporting the forest industry.

The push is to make forestry more sustainable, conserving the resources with their many benefits, while still making use of them. This is backed by a major scientific research effort, including measurement and planning for forest biodiversity, managing forests in drier areas and planting trees better suited to particular environments. New practices have been developed, such as watering trees with effluent and using computer models to help make forestry decisions. As a result our forests are becoming more productive and are expanding into drier areas, with extra benefits such as the control of salinity, and, better still, the revegetation of previously cleared land.

Related sites

• Australia's sustainable forest management (Department of Agriculture, Fisheries and Forestry, Australia)

• Australia state of the environment 2006 (Department of the Environment, Water, Heritage and the Arts, Australia)

• CSIRO, Australia
  • Towards forest sustainability
  • Measuring the value of environmental services in forests

Box 2: Tell me about carbon offsets

Suppose you need to make a plane trip overseas, inevitably leaving carbon dioxide in your wake (plane trips generate about 3 per cent of all carbon emissions). Many airlines now let you buy an 'offset'. With your money, the company can do a variety of things to negate your new contribution to the carbon dioxide burden our atmosphere carries.

For example they can pay someone else to plant trees that can take up and store (or 'sequester') an equivalent amount of carbon dioxide. These need to be new trees of course, not just replacing trees which have just been cut down, though revegetating land that was cleared long ago can constitute an offset.

Offsets can also come from projects that cut the emission of methane (an even more potent global warming gas than carbon dioxide) from livestock, landfills or coal beds. Other options include helping fund projects for renewable energy, like wind, solar or biomass, or projects that promote energy efficiency. Unlike tree planting, these options prevent activities that cause greenhouse gas emissions so can reduce emissions.

Offsets are a relatively new idea, and one that is not yet fully worked out. The standards and regulations are still being developed, and being a largely unregulated market, terms like carbon-neutral are sometimes used inappropriately for commercial gain. In addition, you cannot always be sure your investment will deliver what is promised. Trees planted to sequester carbon dioxide can burn down or will ultimately die, letting the gas back into the air. An investment in 'green energy' might be more certain. Calculations to determine how much carbon dioxide is being saved or stored can be complex and not fully reliable, leading to over-estimations and even double-counting.

Yet offsets are probably here to stay, and they will become more effective and accepted as we sort out the problems. They will form a big part of the carbon trading regimes proposed for Australia and elsewhere, with both individuals and companies taking them up. Companies to broker offsets are now being set up. In principle, at least, they allow emissions to be cut at a relatively low cost, so have less impact on the economy than other means of reducing emissions. Offsets are a part of the solution to climate change; ultimately, we need to reduce our reliance on fossil fuels.

Related sites

• Carbon offsets compared (Choice, Australia)

• How carbon offsets work (How Stuff Works, USA)

• Look, no carbon footprint (New Scientist, 9 March 2007)

• Greenfleet (Greenfleet, Australia)

• Would you pay to offset your air travel emissions? (Ecos, April-May 2007)

• New Internationalist
  • Carbon offsets – the facts (July 2006)
  • 10 things you should know about tree 'offsets' (July 2006)

Box 3: What difference can we make?

Not necessarily so. Those countries have a bigger impact because they have more people. Our impact is driven by lifestyle, whether it be in Australia or in a country like India. Every year each Australian burdens the atmosphere with as much carbon dioxide and other greenhouse gases as the average American (about 30 tonnes of carbon dioxide) due to the high standard of living. Average emissions for an Australian are much higher than for the average person in India or China; of course wealthy people in these countries emit more carbon, but on average their standard of living and therefore their impact is lower. To address the current lack of equity between countries, the Garnaut Report discusses a scheme where emissions entitlements per capita decrease for countries above the global average, and increase for countries below it, so that we all converge on a similar per capita value globally

Advanced nations like Australia have been pouring out large quantities of greenhouse gases for many decades, while India and China have begun more recently. Most of the current burden of carbon dioxide came from chimneys in Europe, North America and Australia, not in Asia. Since we own most of the problem, we should be willing to take the lead to find solutions.

This is more than a symbolic gesture. We could really make a difference if we tried. Let's look at the figures. Global emissions of carbon dioxide are about 30 billion tonnes, or about 5 tonnes per person every year. In Australia, we release about 560 million tonnes or about say 28 tonnes a head (nearly six times the global average). China emits about 5 billion tonnes or 4 tonnes per head (still below the global average). Every year their emissions increase by about 9 per cent or 450 million tonnes, due to China's growing economy.

Suppose you, as the average Australian, cut your emissions by only 10 per cent. That would save about 55 million tonnes a year, the amount China's emissions increase every month or so. That sounds like a waste of time.

But suppose that, spurred by our example, we were joined by other people who live in developed countries, say 10 per cent of the United Kingdom, the USA and Japan. That would save almost 900 million tonnes, well above the annual growth not only in China but in all the rest of the world. This would buy time for the developing nations to refine their technology, make the right sort of investments and ultimately rein in their emissions.

We could not do that overnight, but we could do it over, say, a decade if we were serious. Apart from helping with the immediate problem, it would help us get ready for the really serious cuts, 60 per cent or more, that we need to make by 2050 to help maintain our climate.

Related sites

• Consuming Australia: Main findings (Australian Conservation Foundation)

• Why bother going green? (New Scientist, 17 November 2007)

• Climate Change 2007: Synthesis report (Intergovernmental Panel on Climate Change)

• National greenhouse gas inventory 2006 (Department of Climate Change, Australia)

Activities

• Environment Protection Agency (Government of Victoria, Australia)
  • Home ecological footprint calculator – students calculate their home's ecological footprint online and discuss ways to reduce it.

• Centre for Education and Research in Environmental Strategies (Victoria, Australia)
  • Ecological footprints – students calculate their individual or school ecological footprint then discuss ways to reduce their footprint.

• Powerhouse Museum (New South Wales Government, Australia)
  • Bigfoot – test your ecological footprint – an Australian site for calculating ecological footprints.

• Queensland Government (Australia)
  • Power for a sustainable future – presents a range of student activities on sustainable energy production and use.

• Australian Conservation Foundation (Australia)
  • Consumption atlas – students can search for their ecological footprint, water use or greenhouse pollution by postcode using this online interactive atlas of Australia.

• The University of North Carolina at Chapel Hill (USA)
  • Calculating your carbon footprint – students calculate their household's carbon footprint, compare it to another classmate and discuss the limitations of the footprint calculator.

• Chemical Industry Education Centre (USA)
  • Sustainability-ed: Teachers' notes and classroom activities – presents a range of student activities on sustainability.

Further reading

Useful sites

Outlines the state of the environment and our impact on the Earth.
http://assets.panda.org/downloads/living_planet_report.pdf

Global Footprint Network (USA)

Contains a range of information on ecological footprints.
http://www.footprintnetwork.org/index.php

Australian Broadcasting Corporation

• Carbon bigfoot (Catalyst, 15 November 2007)
  Contains information on carbon emitters and carbon offsetters.
  http://www.abc.net.au/catalyst/stories/s2092087.htm

• Eco footprint (Catalyst, 31 August 2006)
  Reports on an Australian approach to ecological footprint measurements.
  http://www.abc.net.au/catalyst/stories/s1730069.htm

• Environmental auditing (The Science Show, 15 October 2005)
  Investigates the concept of environmental auditing
  http://www.abc.net.au/rn/science/ss/stories/s1479679.htm

• 'Australian dream' killing the country, says scientist (News in Science, 26 November 2002)
  Contains information on consumption in Australia and solutions to reduce our ecological footprint.
  http://www.abc.net.au/science/news/stories/2002/734356.htm

• Discarding the bovver boots: Ecological footprints (Earthbeat, 13 April 2002)
  Discusses the ecological footprint of Australians
  http://www.abc.net.au/rn/science/earth/stories/s530081.htm

The sustainable scale project – ecological footprint (Santa-Barbara Family Foundation, Canada)

A general outline of ecological footprints and their limitations.
http://www.sustainablescale.org/ConceptualFramework/UnderstandingScale/MeasuringScale/EcologicalFootprint.aspx

Redefining progress (USA)

• Ecological footprint
  Provides information and a number of resources for ecological footprints.
  http://www.myfootprint.org/en/

• Ecological footprint of nations 2005 update
  Provides an updated approach to address previous limitations of ecological footprints.
  http://www.rprogress.org/publications/2006/Footprint%20of%20Nations%202005.pdf

The ecological footprint – issues and trends (The University of Sydney, Australia)

An extensive discussion of the value, limitations and modifications to ecological footprints
http://www.isa.org.usyd.edu.au/publications/documents/Ecological_Footprint_Issues_and_Trends.pdf

British Broadcasting Corporation

• Global ecosystems 'face collapse' (BBC News, 24 October 2006)
  Looks at the potential effect of current global consumption levels on ecosystems.
  http://news.bbc.co.uk/2/hi/science/nature/6077798.stm

• The living planet: Facts and figures (BBC News, 24 October 2006)
  Provides data on the planet's natural resources and humanity's demands on those resources.
  http://news.bbc.co.uk/2/hi/science/nature/6080074.stm

South Australia's ecological footprint (Sustainable Living Choices, Government of South Australia)

Provides information on the ecological footprint of South Australia.
http://www.sustainableliving.sa.gov.au/resources/Eco_Footprint_Wallet.pdf

Ecological footprint as an assessment tool for urban development (Centre for Design, RMIT University, Australia)

Explores the effectiveness of ecological footprint analysis for urban development.
http://www.cfd.rmit.edu.au/programs/sustainable_built_environments/ecological_footprint_as_an_assessment_tool_for_urban_development

Glossary

The biocapacity of an ecosystem is calculated by taking into account its area, land type and productivity. Biocapacity is usually expressed in units of global hectares.

biomass. Plant or animal matter (including agricultural waste) used as a fuel or energy source. Alternatively, the total mass of living matter within a given environmental area.

biosphere. The region of Earth and its atmosphere that is inhabited by living organisms.

carbon-neutral. A state whereby emissions of carbon-containing gases are balanced by the amount being stored; for example, balancing carbon dioxide emissions by growing plants which take in carbon dioxide.

carbon offset. An investment in an activity that reduces greenhouse gas emissions or removes them from the atmosphere. Carbon offsets are used to compensate for greenhouse gas emissions from your own activities.

carbon trading. The trading of greenhouse gas emission rights. Participants in carbon trading buy and sell certificates that represent specified amounts of emissions or credits for reductions in emissions. Placing a cost on carbon emissions encourages organisations to reduce them eg. through renewable energy, improved energy efficiency or carbon offsets.

ecological footprint. The amount of biologically productive land and water that is needed to supply resources and absorb wastes. Ecological footprints are usually expressed in units of global hectares.

global hectares (gha). Unit for measuring our demands on the Earth (ecological footprint) and the ability of the Earth to supply our demands (biocapacity). A global hectare is one hectare of land or water with world-average productivity. Measurements in global hectares are adjusted according to the productivity of land or water in a given year. A land type of high productivity (eg. cropland) will have more global hectares than less productive land (eg. pasture) of an equivalent size.

greenhouse gas. A gas that is transparent to incoming solar radiation and absorbs some of the longer wavelength infrared radiation (heat) that the Earth radiates back. The result is that some of the heat given off by the planet accumulates, making the surface and the lower atmosphere warmer. For more information see The greenhouse effect (CSIRO Atmospheric Research, Australia).

Life Cycle Assessment (LCA). An assessment of the impact of a product on the environment throughout its life. Measures what is needed during production and what is produced from 'cradle to grave'. This includes energy and materials used for obtaining the raw materials for the product, product manufacture and assembly, transport of the product, its use and disposal. Wastes produced during the product's life are also accounted for.

unsustainable. Use of resources at a rate that will eventually deplete the resources and/or cause major ecological damage. An activity that uses natural resources at a rate above the natural rate of their replacement.