The principal objective of sustainability indicators is to inform public policy-making as part of the process of sustainability governance. Sustainability indicators can provide information on any aspect of the interplay between the environment and socio-economic activities. Building strategic indicator sets generally deals with just a few simple questions: what is happening? (descriptive indicators), does it matter and are we reaching targets? (performance indicators), are we improving? (efficiency indicators), are measures working? (policy effectiveness indicators), and are we generally better off? (total welfare indicators). One popular general framework used by The European Environment Agency uses a slight modification of the Organisation for Economic Co-operation and Development DPSIR system. This breaks up environmental impact into five stages. Social and economic developments (consumption and production) (D)rive or initiate environmental (P)ressures which, in turn, produces a change in the (S)tate of the environment which leads to (I)mpacts of various kinds. Societal (R)esponses (policy guided by sustainability indicators) can be introduced at any stage of this sequence of events.
The United Nations has developed extensive sustainability measurement tools in relation to sustainable development as well as a System of Integrated Environmental and Economic Accounting.
In the last couple of decades there has arisen a crowded toolbox of quantitative methods used to assess sustainability — including measures of resource use like life cycle assessment, measures of consumption like the ecological footprint and measurements of quality of environmental governance like the Environmental Performance Index. The following is a list of quantitative "tools" used by sustainability scientists - the different categories are for convenience only as defining criteria will intergrade. It would be too difficult to list all those methods available at different levels of organisation so those listed here are at for the global level only.Benchmarks
A benchmark is a point of reference for a measurement. Once a benchmark is established it is possible to assess trends and measure progress. Baseline global data on a range of sustainability parameters is available at list of global sustainability statistics
2010 Biodiversity Indicators Partnership
A sustainability index is an aggregate sustainability indicator that combines multiple sources of data. There is a Consultative Group on Sustainable Development Indices
Many environmental problems ultimately relate to the human effect on those global biogeochemical cycles that are critical to life. Over the last decade monitoring these cycles has become a more urgent target for research:
Sustainability auditing and reporting are used to evaluate the sustainability performance of a company, organization, or other entity using various performance indicators. Popular auditing procedures available at the global level include:
The Natural Step
Triple Bottom Line Accounting
input-output analysis can be used for any level of organization with a financial budget. It relates environmental impact to expenditure by calculating the resource intensity of goods and services.
Development and NGO project auditing
"Litmus test" type indicators are also used in the development and NGO community to test conformity and compliance with the guidelines of sustainable human development and the international Rio Declaration of 1992.
Sustainable development indicator for NGOs and Other Organizations
Global Reporting Initiative Global Reporting Initiative modelling and monitoring procedures. Many of these have only just been developed.
State of the Environment reporting provides general background information on the environment and is progressively including more indicators.
Some accounting methods attempt to include environmental costs rather than treating them as externalities
Part of this process can relate to resource use such as energy accounting or to economic metrics or price system values as compared to non-market economics potential, for understanding resource use. An important task for resource theory (energy economics) is to develop methods to optimize resource conversion processes. These systems are described and analyzed by means of the methods of mathematics and the natural sciences. Human factors, however, have dominated the development of our perspective of the relationship between nature and society since at least the Industrial Revolution, and in particular have influenced how we describe and measure the economic impacts of changes in resource quality. A balanced view of these issues requires an understanding of the physical framework in which all human ideas, institutions, and aspirations must operate.
When oil production first began in the mid-nineteenth century, the largest oil fields recovered fifty barrels of oil for every barrel used in the extraction, transportation and refining. This ratio is often referred to as the Energy Return on Energy Investment (EROI or EROEI). Currently, between one and five barrels of oil are recovered for each barrel-equivalent of energy used in the recovery process. As the EROEI drops to one, or equivalently the Net energy gain falls to zero, the oil production is no longer a net energy source. This happens long before the resource is physically exhausted.
Note that it is important to understand the distinction between a barrel of oil, which is a measure of oil, and a barrel of oil equivalent (BOE), which is a measure of energy. Many sources of energy, such as fission, solar, wind, and coal, are not subject to the same near-term supply restrictions that oil is. Accordingly, even an oil source with an EROEI of 0.5 can be usefully exploited if the energy required to produce that oil comes from a cheap and plentiful energy source. Availability of cheap, but hard to transport, natural gas in some oil fields has led to using natural gas to fuel enhanced oil recovery. Similarly, natural gas in huge amounts is used to power most Athabasca Tar Sands plants. Cheap natural gas has also led to Ethanol fuel produced with a net EROEI of less than 1, although figures in this area are controversial because methods to measure EROEI are in debate.
Insofar as economic growth is driven by oil consumption growth, post-peak societies must adapt. M. King Hubbert believed:
Some economists describe the problem as uneconomic growth or a false economy. At the political right, Fred Ikle has warned about "conservatives addicted to the Utopia of Perpetual Growth". Brief oil interruptions in 1973 and 1979 markedly slowed - but did not stop - the growth of world GDP.
Between 1950 and 1984, as the Green Revolution transformed agriculture around the globe, world grain production increased by 250%. The energy for the Green Revolution was provided by fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon fueled irrigation.
David Pimentel, professor of ecology and agriculture at Cornell University, and Mario Giampietro, senior researcher at the National Research Institute on Food and Nutrition (INRAN), place in their study Food, Land, Population and the U.S. Economy the maximum U.S. population for a sustainable economy at 200 million. To achieve a sustainable economy world population will have to be reduced by two-thirds, says the study. Without population reduction, this study predicts an agricultural crisis beginning in 2020, becoming critical c. 2050. The peaking of global oil along with the decline in regional natural gas production may precipitate this agricultural crisis sooner than generally expected. Dale Allen Pfeiffer claims that coming decades could see spiraling food prices without relief and massive starvation on a global level such as never experienced before.
Although Hubbert peak theory receives most attention in relation to peak oil production, it has also been applied to other natural resources.
Doug Reynolds predicted in 2005 that the North American peak would occur in 2007. Bentley (p. 189) predicted a world "decline in conventional gas production from about 2020".
Peak coal is significantly further out than peak oil, but we can observe the example of anthracite in the USA, a high grade coal whose production peaked in the 1920s. Anthracite was studied by Hubbert, and matches a curve closely. Pennsylvania's coal production also matches Hubbert's curve closely, but this does not mean that coal in Pennsylvania is exhausted—far from it. If production in Pennsylvania returned at its all-time high, there are reserves for 190 years. Hubbert had recoverable coal reserves worldwide at 2500 × 109 metric tons and peaking around 2150(depending on usage).
More recent estimates suggest an earlier peak. Coal: Resources and Future Production (PDF 630KB ), published on April 5, 2007 by the Energy Watch Group (EWG), which reports to the German Parliament, found that global coal production could peak in as few as 15 years. Reporting on this Richard Heinberg also notes that the date of peak annual energetic extraction from coal will likely come earlier than the date of peak in quantity of coal (tons per year) extracted as the most energy-dense types of coal have been mined most extensively. A second study, The Future of Coal by B. Kavalov and S. D. Peteves of the Institute for Energy (IFE), prepared for European Commission Joint Research Centre, reaches similar conclusions and states that ""coal might not be so abundant, widely available and reliable as an energy source in the future".
Work by David Rutledge of Caltech predicts that the total of world coal production will amount to only about 450 gigatonnes. This implies that coal is running out faster than usually assumed.
Finally, insofar as global peak oil and peak in natural gas are expected anywhere from imminently to within decades at most, any increase in coal production (mining) per annum to compensate for declines in oil or NG production, would necessarily translate to an earlier date of peak as compared with peak coal under a scenario in which annual production remains constant.
In a paper in 1956, after a review of US fissionable reserves, Hubbert notes of nuclear power:
Technologies such as the thorium fuel cycle, reprocessing and fast breeders can, in theory, considerably extend the life of uranium reserves. Roscoe Bartlett claims
Caltech physics professor David Goodstein has stated that
Hubbert applied his theory to "rock containing an abnormally high concentration of a given metal" and reasoned that the peak production for metals such as copper, tin, lead, zinc and others would occur in the time frame of decades and iron in the time frame of two centuries like coal. The price of copper rose 500% between 2003 and 2007 was by some attributed to peak copper. Copper prices later fell, along with many other commodities and stock prices, as demand shrank from fear of a global recession. Lithium availability is a concern for a fleet of Li-ion battery using cars but a paper published in 1996 estimated that world reserves are adequate for at least 50 years. A similar prediction for platinum use in fuel cells notes that the metal could be easily recycled.
Phosphorus supplies are essential to farming and depletion of reserves is estimated at somewhere from 60 to 130 years. Individual countries supplies vary widely; without a recycling initiative America's supply is estimated around 30 years. Phosphorus supplies affect total agricultural output which in turn limits alternative fuels such as biodiesel and ethanol.
Hubbert's original analysis did not apply to renewable resources. However over-exploitation often results in a Hubbert peak nonetheless. A modified Hubbert curve applies to any resource that can be harvested faster than it can be replaced.
For example, a reserve such as the Ogallala Aquifer can be mined at a rate that far exceeds replenishment. This turns much of the world's underground water and lakes into finite resources with peak usage debates similar to oil. These debates usually center around agriculture and suburban water usage but generation of electricity from nuclear energy or coal and tar sands mining mentioned above is also water resource intensive. The term fossil water is sometimes used to describe aquifers whose water is not being recharged.Fisheries: At least one researcher has attempted to perform Hubbert linearization (Hubbert curve) on the whaling industry, as well as charting the transparently dependent price of caviar on sturgeon depletion. Another example is the cod of the North Sea. The comparison of the cases of fisheries and of mineral extraction tells us that the human pressure on the environment is causing a wide range of resources to go through a depletion cycle which follows a Hubbert curve.