Frequently Asked Questions:

How the Ecological Footprint works

(and answers to common questions)

Ecological Footprint Accounting – The Basics

The Ecological Footprint answers a central question: how much nature do we have, and how much we use?

Life, human and wildlife, competes for biologically productive areas. The Footprint measures the biologically productive area needed to provide for everything people demand: fruits and vegetables, fish, wood, fibres, absorption of carbon dioxide from fossil fuel burning, and space for buildings and roads.

Biocapacity is the productive area that can regenerate the renewable resources that people demand from nature. As we phase out fossil fuel — as anticipated in most imaginable scenarios — biocapacity will not only have to feed us and provide fibre and timber. It also will have to help us replace fossil fuel. Therefore, mapping an economy’s material and energy dependence on biocapacity provides a comprehensive view of the competing material demands on the planet.

The underlying rational for Ecological Footprint accounting is simple: We can add up all productive surface areas that fulfil human demand for renewable natural resources. The sum of these areas, the Footprint, then can be compared with the existing productive area (biocapacity). Further, since each area differs in its productivity, they are measured in global hectares, or productivity adjusted hectares. This makes areas globally comparable. For instance, if a hectare produces only x% of the world average, it is counted as x% of a global hectare.

Through this accounting, all demands on nature (but not all environmental problems) can be brought together and can be compared. Similarly, the biocapacity of any country or region can be compared.

This is how we get to answer the question of: How many Earth(s) does humanity currently use? Answer: 1.7. (Check out the data platform with maps and the newest results. Download more results here).

It is possible for human demand to exceed what the Earth renews for a while. But the consequences of overuse are depletion of ecological assets (such as loss of topsoil, forests, fish, groundwater), biodiversity loss, and the accumulation of CO₂ in the atmosphere.

A global Ecological Footprint that is smaller than what Earth can renew is a necessary condition for sustainability. But it is not enough to guarantee sustainability. There can still be erosion, destruction, and build- up of pollution if the Ecological Footprint is smaller than what our planet can renew.

However, we know for certain that we cannot be sustainable if humanity’s Footprint is larger than the planet’s biocapacity. The Ecological Footprint has been referred to by the Swiss Federal Council’s Cleantech Master Plan and the World Business Council for Sustainable Development (WBCSD), which employed it extensively in its Vision 2050 strategy drafted with 30 member companies. WBCSD advocated reducing humanity’s Footprint to one planet by 2050. (WBCSD – Vision 2050).

Question: What does the Footprint leave out? How does it deal with pollution?

Answer: The Footprint measures how much nature we need and how much we have. To keep the Ecological Footprint results comparable and transparent, the accounts are simplified. They are also limited by the amount and quality of the data available through the United Nations. Still, the results are most likely underestimations of actual resource constraints. But even more detailed Footprint calculations could not capture every environmental problem. Nevertheless, a small enough Footprint is a prerequisite for sustainability: Our demand on nature must be less than what nature can regenerate. Air pollution such as elevated low-level ozone concentrations, volatile organic compounds or particulates are a threat primarily to human health. Obviously, human health is a fundamental objective, but not as relevant as nature’s ability to renew, which is what the Footprint measures. The same applies to (short or medium term) plastic waste floating in the sea. Still, when, for example, contaminated water is no longer usable, soils or ecosystems are destroyed, or ecosystem productivity reduced through acid rain, the environment loses some of its reproductive capacity. This loss would be captured in Ecological Footprint accounts.

Question: How does the Footprint deal with non-renewable resources such as copper, rare earths or phosphorus?

Answer: The consumption of non-renewable resources is not in itself a problem for the environment, but rather for production technologies that depend on it. Also, most non-renewable resources (such as lithium or copper) are not limited by how much ore lies underground, but by how much energy and effort it takes to dig up those ores and concentrate them. These resources become ecologically problematic when their excavation and refinement consumes large amounts of energy, or if their subsequent use causes large amounts of greenhouse gas emissions, or soil, air or water pollution. All these impacts represent additional demand on biocapacity, or higher Footprints.

The circular economy makes it possible to carefully manage non-renewable resources by keeping them from being wasted or discarded.

Question: What is the relevance of the Footprint metrics for biodiversity?

Answer: When a plant or animal species becomes extinct, the Ecological Footprint indeed does not change. However, the main condition for animal and plant species to survive and thrive are functioning ecosystems of sufficient size. A declining Ecological Footprint is therefore the most important contribution to preserving biodiversity. This reduction reduces human demand on productive surfaces and leaves space for wild species. For this reason, WWF, one of the world’s largest environment and conservation organizations, has embraced the Footprint and made reducing the human Footprint to less than one planet one of its two core goals.

Question: The largest portion of the Ecological Footprint is CO₂ emissions. Would it not make more sense to focus directly on CO₂, and leave aside the complicated additional calculations?

Answer: Indeed, the carbon Footprint is currently the largest portion of the Ecological Footprint of most countries. However, to reach the 2°C climate target stipulated by the Paris agreement, the carbon Footprint worldwide has to be zero well before 2050, and even earlier with a 1.5°C target. This makes the use of the full Ecological Footprint even more central.

One reason is that in a decarbonized world, biocapacity will become the primary source for any value chain, complemented by technologies that can harvest energy without compromising biocapacity (such as photovoltaics on roofs or unproductive areas, or off-shore windmills). Also, one of the challenges of decarbonization becomes how to reduce CO₂ emissions without putting more pressure on the rest of the biosphere, for instance by increasing agrofuel production. Such a shift would not only add pressure on ecosystems but could also have significant social impact if such biofuel production competes with areas for food. This underlines why a comprehensive approach is needed in order to succeed with the transformation.