The ecological footprint definition is a measurement that compares rates of human resource consumption and waste generation with the biosphere’s rates of resource regeneration and waste energy assimilation, expressed in terms of the area necessary to maintain these flows. Ecological footprints represent the biologically productive space required to produce the resources and absorb the waste biomass of a given population, organization, or product using prevailing management and technology.
Ecological Overshoot
The nature of ecological issues and ecological limit may be one of the most influential misconceptions of the sustainability debate. A former executive director of the United Nations (UN) Population Fund stated that ‘‘many environmentalists think [that the carrying capacity of Earth] is 4 billion, maximum. But now we have 6 billion people.’’ The continued growth of the human population and resource and energy consumption, however, is only an apparent contradiction. In reality, ecological issues can be exceeded for a period of time because nature reacts with inertia. More precisely, natural capital can be harvested faster than it regenerates, thereby depleting the natural capital stock. Ecologists call this state ecological overshoot.
The concept of overshoot reconciles the apparently contradictory assertions that standards of living are waxing while ecological capacity is waning. Nevertheless, uncertainties remain regarding the possible impacts of prolonged overshoot. Some fear that unsustainable harvests will trigger the sudden collapse of ecosystems, leaving fisheries and other dynamic resource stocks irreversibly damaged. Others hope that the contraction of ecosystem services will be slower and more forgiving.
The delayed effects of overshoot and difficulty of valuing ecosystem services prevent markets and uninformed policy from forming corrective feedback mechanisms. Without adequate feedback mechanisms, such as systematic accounting that compares human demands on nature with nature’s capacity to regenerate, overshoot can go unnoticed, thereby undermining humanity’s future. Industrial economies in particular can exceed ‘‘sustainable limits’’ by masking resource depletion and decreasing energy returns on investment with technological advances, inexpensive energy, and easy access to distant resources. Particularly on the waste side, feedback is weak: CO2 from fossil fuel burning leaves tailpipes with ease, independent of the increasing CO2 concentration in the atmosphere.
No national government or UN agency operates a comprehensive accounting system to document the extent to which human demands fit within the capacity of existing ecosystems. The ecological footprint is one of the few tools that attempts integrated resources accounting.
The purpose of ecological footprint definition is not only to illustrate the possibility of overshoot but also to offer a robust tool to demonstrate its occurrence. As a resources accounting tool, it can help determine who is contributing, and how much, to the overall impact of humanity. Most important, it can evaluate potential strategies for avoiding overshoot.
Ecological Footprint Calculation Methods
There are two basic to calculate ecological footprint: component- and compound-based. The first calculates the footprint of individual goods or organizations. This bottom-up, component-based method first identifies all relevant items and then assesses the ecological footprint of each item using life-cycle data. The overall accuracy of the final result depends on the completeness of the component list as well as the reliability of the life-cycle assessment (LCA) of each identified component. This approach provides a high level of detail but has limitations due to LCAs’ frequent inaccuracies, incompleteness, and poorly defined boundaries. The component-based method also has difficulty with data gaps and indirect expenditures outside of an organization’s inventories, such as public infrastructure and military.
The compound-based method uses a top-down approach to aggregate economic and environmental statistics into national ecological footprints. Compound footprinting, which underlies the national results presented in this article, calculate ecological footprint using aggregate national data. This information is more complete than subnational sources and LCAs and captures both direct and indirect consumption. For instance, to calculate the paper footprint of a country, information about the total amount consumed is typically available and sufficient for the task. In contrast to the component method, there is no need to know which portions of the overall paper consumption were used for which purposes, aspects that are poorly documented in statistical data collections.
