Sustainability

For other uses of the term "Sustain", see Sustain (disambiguation).

Blue Marble NASA composite images: 2001 (left), 2002 (right).

Sustainability is the ability to maintain. It can be defined in biological terms as the ability of an ecosystem to maintain ecological processes, functions, biodiversity and productivity over time.

The word 'sustainability' has become a wide-ranging term that can be applied to many facets of life on Earth, from a local to a global scale and over various time periods. Long-lived and healthy wetlands and forests are examples of sustainable biological systems. Invisible chemical cycles redistribute water, oxygen, nitrogen and carbon through the world's living and non-living systems, and have sustained life for millions of years. As the earth’s human population has increased, natural ecosystems have declined and changes in the balance of natural cycles has had a negative impact on both humans and other living systems.

Scientific evidence shows that humanity is not living in a sustainable manner. Efforts to live more sustainably can take many forms from reorganizing living conditions (e.g., ecovillages, eco-municipalities and sustainable cities), reappraising economic sectors (green building, sustainable agriculture), or work practices (sustainable architecture), using science to develop new technologies (green technologies, renewable energy), to adjustments in individual lifestyles.

Definition

Cooperative intersection of the social, environmental and economic pillars of sustainability

Definitions of sustainability may be expressed as statements of fact, intent, or value with sustainability treated as either a "journey" or "destination". Where we are now, where we need to be going, and how we are to get there are all open to interpretation and will depend on the particular context under consideration. What can meaningfully be described as sustainable will depend on the scale of space and time that is appropriate to the item under consideration. For example, if time criteria have not been met, then assertions of sustainability are more like predictions than definitions. This difficult mix has been described as a "dialogue of values that defies consensual definition." Sustainability has been regarded as both an important but unfocused concept like "liberty" or "justice" and as a feel-good buzzword with little meaning or substance. The idea of sustainable development is sometimes viewed as an oxymoron because development inevitably depletes and degrades the environment. Consequently some definitions either avoid the word development and use the term sustainability exclusively, or emphasise the environmental component, as in "environmentally sustainable development."

Another representation of sustainability showing how both economy and society are constrained by environmental limits

The dimensions of sustainability are often taken to be: environmental, social and economic, known as the "three pillars". These can be depicted as three overlapping circles (or ellipses), to show that they are not mutually exclusive and can be mutually reinforcing. While this model initially improved the standing of environmental concerns, it has since been criticised for not adequately showing that societies and economies are fundamentally reliant on the natural world. According to English environmentalist and author Jonathon Porritt, "The economy is, in the first instance, a subsystem of human society ... which is itself, in the second instance, a subsystem of the totality of life on Earth (the biosphere). And no subsystem can expand beyond the capacity of the total system of which it is a part." For this reason a second diagram shows economy as a component of society, both bounded by, and dependent upon, the environment. As the American World Bank ecological economist Herman Daly famously asked, "what use is a sawmill without a forest?" The concept of living within environmental constraints yields a definition of sustainable development: "improving the quality of human life while living within the carrying capacity of supporting eco-systems."

The Earth Charter goes beyond defining what sustainability is, and seeks to establish the values and direction needed to achieve it: "We must join together to bring forth a sustainable global society founded on respect for nature, universal human rights, economic justice, and a culture of peace. Towards this end, it is imperative that we, the peoples of Earth, declare our responsibility to one another, to the greater community of life, and to future generations."

History

Main article: History of sustainability

In early human history the environmental impacts of small bands of hunter-gatherers would have been relatively small, even though the use of fire and the desire for specific foods may have altered the natural composition of plant and animal communities. With the Neolithic Revolution 8,000 and 10,000 years ago came the emergence of agriculture and settled communities. Societies outgrowing their local food supply or depleting critical resources either moved on or faced collapse. In contrast, stable communities of shifting cultivators and horticulturists existed in New Guinea and South America, and large agrarian communities in China, India, Polynesia and elsewhere have farmed in the same localities for centuries.

Technological advances over several millennia gave humans increasing control over the environment. But it was the Western industrial revolution of the 17th to 19th centuries that tapped into the vast growth potential of the energy in fossil fuels to power sophisticated machinery technology. Such conditions led to a human population explosion and unprecedented industrial, technological and scientific growth that has continued to this day. From 1650 to 1850 the global population doubled from around 500 million to 1 billion people.

By the 20th century, the industrial revolution had resulted in an exponential increase in the human consumption of resources and an increase in health, wealth and population. Ecology as a new scientific discipline was gaining general acceptance and ideas now part and parcel to sustainability were being explored including the recognition of the interconnectedness of living systems, the importance of global natural cycles, the passage of energy through trophic levels of living systems.

After the deprivations of the Great Depression and World War II the developed world entered a post-1950s "great acceleration” of growth and population while a gathering environmental movement pointed out that there were environmental costs associated with the many material benefits that were now being enjoyed. Technological innovations included plastics, synthetic chemicals and nuclear energy as fossil fuels also continued to transform society. The negative influences of the new technology were documented by American marine biologist and naturalist Rachel Carson in her influential book Silent Spring in 1962. A period of peak oil production was anticipated in 1956 by American geoscientist M. King Hubbert's peak oil theory. In the 1970s environmentalism's concern with pollution, the population explosion, consumerism and the depletion of finite resources found expression in Small Is Beautiful, by British economist E. F. Schumacher in 1973, and The Limits to Growth published by the global think tank, the Club of Rome, in 1975.

By the late twentieth century environmental problems were becoming global in scale. and the 1973 and 1979 energy crises demonstrated the extent to which the global community had become dependent on a nonrenewable resource.

In 1987 the United Nation's World Commission on Environment and Development (the Brundtland Commission), in its report Our Common Future suggested that sustainable development was needed to meet human needs while not increasing environmental problems. In 1961 almost all countries in the world had the capacity to meet their own demand but by 2005 the situation had changed and many countries were able to meet their needs only by importing resources from other nations. A move toward more sustainable living emerged, based on increasing public awareness and adoption of recycling, and renewable energies. The development of renewable sources of energy in the 1970s and 80's, primarily in wind turbines and photovoltaics and increased use of hydroelectricity, presented more sustainable alternatives to fossil fuel and nuclear energy generation.

In the 21st century there is heightened awareness of the threat posed by the human-induced greenhouse effect. Ecological economics now seeks to bridge the gap between ecology and traditional neoclassical economics: and proposes an inclusive and ethical economic model for society. Many new techniques have arisen to help measure and implement sustainability, including Life Cycle Assessment (the Cradle to Cradle, the Ecological Footprint Analysis, and green building. The work of Bina Agarwal and Vandana Shiva amongst many others, has brought some of the cultural knowledge of traditional, sustainable agrarian societies into the academic discourse on sustainability, and blended that knowledge with modern scientific principles.

Principles and concepts

Sustainability science and environmental science form the basis for much of the philosophical and analytic framework of sustainability. Quantitative data is collected through sustainability measurement and this data is then used in governance for sustainability.

Scale and context

Sustainability is studied and managed over many scales (levels or frames of reference) of time and space and in many contexts of environmental, social and economic organization. The focus ranges from the total carrying capacity (sustainability) of planet Earth to the sustainability of economic sectors, ecosystems, countries, municipalities, neighbourhoods, home gardens, individual lives, individual goods and services, occupations, lifestyles, behaviour patterns and so on. In short, it can entail the full compass of biological and human activity or any part of it. As Daniel Botkin, author and environmentalist, has stated: "We see a landscape that is always in flux, changing over many scales of time and space."

Global goals

At the global level a number of key goals have been isolated:

• Intergenerational equity - providing future generations with the same environmental potential as presently exists
• Decoupling economic growth from environmental degradation - managing economic growth to be less resource intensive and less polluting
• Integration of all pillars - integrating environmental, social and economic sectors when developing sustainability policies
• Ensuring environmental adaptability and resilience - maintaining and enhancing the adaptive capacity of the environmental system
• Preventing irreversible long-term damage to ecosystems and human health
• Ensuring distributional equity - avoiding unfair or high environmental costs on vulnerable populations
• Accepting global responsibility - assuming responsibility for environmental effects that occur outside areas of jurisdiction
• Education and grassroots involvement - people and communities investigating problems and developing new solutions

Consumption, population, technology, resources

Further information: I PAT

The overall driver of human impact on Earth systems is the consumption of biophysical resources. Human consumption can be divided into three key components: population numbers, levels of consumption (affluence), and impact per unit of resource use (which depends on the technology used). This has been expressed through an equation:

I = P × A × T

Where: I = Environmental impact, P = Population, A = Affluence, T = Technology

Historically, humanity has responded to a demand for more resources by trying to increase supply. Sustainability, instead, applies demand management of all goods and services by promoting reduced consumption, using renewable resources where possible, and encouraging practices that minimise resource intensity while maximising resource productivity. Careful resource management is applied at many scales, but especially at the levels of economic sectors like agriculture, manufacturing and industry as well as to individual goods and services and the consumption patterns of households and individuals.

Population

Main article: Population control

Graph showing human population growth from 10,000 BC – AD 2000, illustrating current exponential growth

According to the 2008 Revision of the official United Nations population estimates and projections, the world population is projected to reach 7 billion early in 2012, up from the current 6.9 billion (May 2009), to exceed 9 billion people by 2050. Most of the increase will be in developing countries whose population is projected to rise from 5.6 billion in 2009 to 7.9 billion in 2050. This increase will be distributed among the population aged 15–59 (1.2 billion) and 60 or over (1.1 billion) because the number of children under age 15 in developing countries will decrease. In contrast, the population of the more developed regions is expected to undergo only slight increase from 1.23 billion to 1.28 billion, and this would have declined to 1.15 billion but for a projected net migration from developing to developed countries, which is expected to average 2.4 million persons annually from 2009 to 2050. Long-term estimates of global population suggest a peak at around 2070 of nine to ten billion people, and then a slow decrease to 8.4 billion by 2100.

Emerging economies like those of China and India aspire to the living standards of the Western world as does the non-industrialized world in general. It is the combination of population increase in the developing world and unsustainable consumption levels in the developed world that poses a stark challenge to sustainability.

Direct and indirect environmental impacts

At a fundamental level energy flow and biogeochemical cycling set an upper limit on the number and mass of organisms in any ecosystem. Human impacts on the Earth are demonstrated through detrimental changes in the global biogeochemical cycles of chemicals that are critical to life, most notably those of water, oxygen, carbon, nitrogen and phosphorus.

• Global biophysical cycles critical for life
• 
  Nitrogen cycle
• 
  Water cycle
• 
  Carbon cycle
• 
  Oxygen cycle
• 
  Phosphorus cycle

Measurement

Main article: Sustainability measurement

To survive on planet Earth humans must live within its measurable biophysical constraints. By establishing quantitative measures for sustainability it is possible to set goals, apply management strategies, and measure progress. The Natural Step (TNS) framework developed by Karl-Henrik Robèrt examines sustainability and resource use from its thermodynamic foundations to determine how humans use and apportion natural capital in a way that is sustainable and just. The TNS framework's system conditions of sustainability provide a means for the scientifically based measurement of sustainability. Natural capital includes resources from the earth's crust (i.e., minerals, oil), those produced by humans (synthetic substances), and those of the biosphere. Equitable access to natural capital is also a component of sustainability. The energy generated in use of resources—referred to as exergy—can be measured as the embodied energy of a product or service over its life cycle. Its analysis, using methods such as Life Cycle Analysis or Ecological Footprint analysis provide basic indicators of sustainability on various scales.

There is now a vast number of sustainability indicators, metrics, benchmarks, indices, reporting procedures, audits and more. They include environmental, social and economic measures separately or together over many scales and contexts. Environmental factors are integrated with economics through ecological economics, resource economics and thermoeconomics, and social factors through metrics like the Happy Planet Index which measures the well-being of people in the nations of the world while taking into account their environmental impact. Some of the best known and most widely used sustainability measures are listed in the side bar, they include corporate sustainability reporting, Triple Bottom Line accounting, and estimates of the quality of sustainability governance for individual countries using the Environmental Sustainability Index and Environmental Performance Index.

Carrying capacity

Further information: Carrying capacity

Ecological footprint for different nations compared to their Human Development Index (HDI)

Gathering data show humans are not living within carrying capacity of the planet. The Ecological footprint measures human consumption in terms of the biologically productive land needed to provide the resources, and absorb the wastes of the average global citizen. In 2008 it required 2.7 global hectares per person, 30% more than the natural biological capacity of 2.1 global hectares (assuming no provision for other organisms). The resulting ecological deficit must be met from unsustainable extra sources and these are obtained in three ways: embedded in the goods and services of world trade; taken from the past (e.g. fossil fuels); or borrowed from the future as unsustainable resource usage (e.g. by over exploiting forests and fisheries).

The figure (right) indicates the sustainability of countries in terms of their Ecological Footprint to the UN Human Development Index (a measure of standard of living): it shows what is necessary for countries to maintain an acceptable standard of living for their citizens while, at the same time, living at a globally sustainable level. The general trend is for higher standards of living to become less sustainable. As always population growth has a marked influence on levels of consumption and the efficiency of resource use. The sustainability goal is to raise the global standard of living without increasing the use of resources beyond globally sustainable levels; that is, to not exceed "one planet" consumption. Information generated by reports at the national, regional and city scales confirm the global trend towards societies that are becoming less sustainable over time.

Global human impact on biodiversity

Chicago, a heavily urbanised area devoid of natural ecosystems

Further information: Millennium Ecosystem Assessment

The Millennium Ecosystem Assessment is an international synthesis by over 1000 of the world's leading biological scientists that analyses the state of the Earth’s ecosystems. It concludes that human activity is having a significant and escalating impact on the biodiversity of world ecosystems, reducing both their resilience and biocapacity. The report refers to natural systems as humanity's "life-support system", providing essential "ecosystem services". The assessment measures 24 ecosystem services concluding that only four have shown improvement over the last 50 years, 15 are in serious decline, and five are in a precarious condition.

Environmental dimension

Healthy ecosystems provide vital goods and services to humans and other organisms. There are two major ways of reducing negative human impact and enhancing ecosystem services:

a) Environmental management. This direct approach is based largely on information gained from earth science, environmental science and conservation biology.

However, this is management at the end of a long series of indirect causal factors that are initiated by human consumption, so a second approach is through demand management of human resource use.

b) Management of human consumption of resources, an indirect approach based largely on information gained from economics. Herman Daly has suggested three broad criteria for ecological sustainability: renewable resources should provide a sustainable yield (the rate of harvest should not exceed the rate of regeneration); for non-renewable resources there should be equivalent development of renewable substitutes; waste generation should not exceed the assimilative capacity of the environment.

Environmental management

Further information: Environmental management and Natural resource management

At the global scale and in the broadest sense environmental management involves the oceans, freshwater systems, land and atmosphere, but following the sustainability principle of scale it can be equally applied to any ecosystem from a tropical rainforest to a home garden.

Atmosphere, oceans, freshwater, land, forests, cultivated land

Atmosphere

Further information: Earth's atmosphere and Climate change

In March 2009 at a meeting of the Copenhagen Climate Council 2,500 climate experts from 80 countries issued a keynote statement that there is now "no excuse" for failing to act on global warming and that without strong carbon reduction targets "abrupt or irreversible" shifts in climate may occur that "will be very difficult for contemporary societies to cope with". Management of the global atmosphere now involves assessment of all aspects of the carbon cycle to identify opportunities to address human-induced climate change and this has become a major focus of scientific research because of the potential catastrophic effects on biodiversity and human communities (see Energy below).

Other human impacts on the atmosphere include the air pollution in cities, the pollutants including toxic chemicals like nitrogen oxides, sulphur oxides, volatile organic compounds and particulate matter that produce photochemical smog and acid rain, and the chlorofluorocarbons that degrade the ozone layer. Anthropogenic particulates such as sulphate aerosols in the atmosphere reduce the direct irradiance and reflectance (albedo) of the Earth's surface. Known as global dimming the decrease is estimated to have been about 4% between 1960 and 1990 although the trend has subsequently reversed. Global dimming may have disturbed the global water cycle by reducing evaporation and rainfall in some areas. It also creates a cooling effect and this may have partially masked the effect of greenhouse gases on global warming.

Oceans

Further information: Coastal management and Overfishing

A selection of the world's saltwater fish

Ocean circulation patterns have a strong influence on climate and weather and, in turn, the food supply of both humans and other organisms. Scientists have warned of the possibility, under the influence of climate change, of a sudden alteration in circulation patterns of ocean currents that could drastically alter the climate in some regions of the globe. Major human environmental impacts occur in the more habitable regions of the ocean fringes – the estuaries, coastline and bays. Ten per cent of the world's population – about 600 million people – live in low-lying areas vulnerable to sea level rise. Trends of concern that require management include: over-fishing (beyond sustainable levels); coral bleaching due to ocean warming and ocean acidification due to increasing levels of dissolved carbon dioxide; and sea level rise due to climate change. Because of their vastness oceans also act as a convenient dumping ground for human waste. Remedial strategies include: more careful waste management, statutory control of overfishing by adoption of sustainable fishing practices and the use of environmentally sensitive and sustainable aquaculture and fish farming, reduction of fossil fuel emissions and restoration of coastal and other marine habitat.

Freshwater

Further information: Water crisis

Water covers 71% of the Earth's surface. Of this, 97.5% is the salty water of the oceans and only 2.5% freshwater, most of which is locked up in the Antarctic ice sheet. The remaining freshwater is found in lakes, rivers, wetlands, the soil, aquifers and atmosphere. All life depends on the solar-powered global water cycle, the evaporation from oceans and land to form water vapour that later condenses from clouds as rain, which then becomes the renewable part of the freshwater supply. Awareness of the global importance of preserving water for ecosystem services has only recently emerged as, during the 20th century, more than half the world’s wetlands have been lost along with their valuable environmental services. Biodiversity-rich freshwater ecosystems are currently declining faster than marine or land ecosystems making them the world's most vulnerable habitats. Increasing urbanization pollutes clean water supplies and much of the world still does not have access to clean, safe water. In the industrial world demand management has slowed absolute usage rates but increasingly water is being transported over vast distances from water-rich natural areas to population-dense urban areas and energy-hungry desalination is becoming more widely used. Greater emphasis is now being placed on the improved management of blue (harvestable) and green (soil water available for plant use) water, and this applies at all scales of water management.

Land

Further information: Land use

Loss of biodiversity stems largely from the habitat loss and fragmentation produced by the human appropriation of land for development, forestry and agriculture as natural capital is progressively converted to man-made capital. Land use change is fundamental to the operations of the biosphere because alterations in the relative proportions of land dedicated to urbanisation, agriculture, forest, woodland, grassland and pasture have a marked effect on the global water, carbon and nitrogen biogeochemical cycles and this can impact negatively on both natural and human systems. At the local human scale major sustainability benefits accrue from the pursuit of green cities and sustainable parks and gardens.

Forests

Further information: Forestry and Ecoforestry

Since the Neolithic Revolution about 47% of the world’s forests have been lost to human use. Present-day forests occupy about a quarter of the world’s ice-free land with about half of these occurring in the tropics In temperate and boreal regions forest area is gradually increasing (with the exception of Siberia), but deforestation in the tropics is of major concern.

Beech Forest – Grib Skov, Denmark

Forests moderate the local climate and the global water cycle through their light reflectance (albedo) and evapotranspiration. They also conserve biodiversity, protect water quality, preserve soil and soil quality, provide fuel and pharmaceuticals, and purify the air. These free ecosystem services have no market value and so forest conservation has little appeal when compared with the economic benefits of logging and clearance which, through soil degradation and organic decomposition returns carbon dioxide to the atmosphere. The United Nations Food and Agriculture Organization (FAO) estimates that about 90% of the carbon stored in land vegetation is locked up in trees and that they sequester about 50% more carbon than is present in the atmosphere. Changes in land use currently contribute about 20% of total global carbon emissions (heavily logged Indonesia and Brazil are a major source of emissions). Climate change can be mitigated by sequestering carbon in reafforestation schemes, plantations and timber products. Also wood biomass can be utilized as a renewable carbon-neutral fuel. The FAO has suggested that, over the period 2005–2050, effective use of tree planting could absorb about 10–20% of man-made emissions – so monitoring the condition of the world's forests must be part of a global strategy to mitigate emissions and protect ecosystem services. However, climate change may pre-empt this FAO scenario as a study by the International Union of Forest Research Organizations in 2009 concluded that the stress of a 2.5C (4.5F) temperature rise above pre-industrial levels could result in the release of vast amounts of carbon so the potential of forests to act as carbon "sinks" is "at risk of being lost entirely".

Cultivated land

Main article: Sustainable agriculture

A rice paddy. Rice, wheat, corn and potatoes make up more than half the world's food supply

Feeding more than six billion human bodies takes a heavy toll on the Earth’s resources. This begins with the appropriation of about 38% of the Earth’s land surface and about 20% of its net primary productivity. Added to this are the resource-hungry activities of industrial agribusiness – everything from the crop need for irrigation water, synthetic fertilizers and pesticides to the resource costs of food packaging, transport (now a major part of global trade) and retail. Food is essential to life. But the list of environmental costs of food production is a long one: topsoil depletion, erosion and conversion to desert from constant tillage of annual crops; overgrazing; salinization; sodification; waterlogging; high levels of fossil fuel use; reliance on inorganic fertilisers and synthetic organic pesticides; reductions in genetic diversity by the mass use of monocultures; water resource depletion; pollution of waterbodies by run-off and groundwater contamination; social problems including the decline of family farms and weakening of rural communities.

All of these environmental problems associated with industrial agriculture and agribusiness are now being addressed through such movements as sustainable agriculture, organic farming and more sustainable business practices.

Extinctions

Further information: Extinction

The extinct Dodo (Raphus cucullatus)

Although biodiversity loss can be monitored simply as loss of species, effective conservation demands the protection of species within their natural habitats and ecosystems. Following human migration and population growth, species extinctions have progressively increased to a rate unprecedented since the Cretaceous–Tertiary extinction event. Known as the Holocene extinction event this current human-induced extinction of species ranks as one of the worlds six mass extinction events. Some scientific estimates indicate that up to half of presently existing species may become extinct by 2100. Current extinction rates are 100 to 1000 times their prehuman levels with more than 10% birds and mammals threatened, about 8% of plants, 5% of fish and more than 20% of freshwater species.

The 2008 IUCN Red List warns that long-term droughts and extreme weather put additional stress on key habitats and, for example, lists 1,226 bird species as threatened with extinction, which is one-in-eight of all bird species. The Red List Index also identifies 44 tree species in Central Asia as under threat of extinction due to over-exploitation and human development and threatening the region's forests which are home to more than 300 wild ancestors of modern domesticated fruit and nut cultivars.

Biological invasions

Further information: Introduced species

Kudzu (Pueraria lobata) infesting trees in Atlanta, Georgia, USA

In many parts of the industrial world land clearing for agriculture has diminished and here the greatest threat to biodiversity, after climate change, has become the destructive effect of invasive species. Increasingly efficient global transport has facilitated the spread of organisms across the planet. The potential danger of this aspect of globalization is starkly illustrated through the spread of human diseases like HIV AIDS, mad cow disease, bird flu and swine flu, but invasive plants and animals are also having a devastating impact on native biodiversity. Non-indigenous organisms can quickly occupy disturbed land and natural areas where, in the absence of their natural predators, they are able to thrive. At the global scale this issue is being addressed through the Global Invasive Species Information Network but there is improved international biosecurity legislation to minimise the transmission of pathogens and invasive organisms. Also, through CITES legislation there is control the trade in rare and threatened species. Increasingly at the local level public awareness programs are alerting communities, gardeners, the nursery industry, collectors, and the pet and aquarium industries, to the harmful effects of potentially invasive species.

Management of human consumption

Further information: Consumption (economics)

Helix of sustainability – the carbon cycle of manufacturing

The underlying driver of direct human impacts on the environment is human consumption. This impact is reduced by not only consuming less but by also making the full cycle of production, use and disposal more sustainable. Consumption of goods and services can be analysed and managed at all scales through the chain of consumption, starting with the effects of individual lifestyle choices and spending patterns, through to the resource demands of specific goods and services, the impacts of economic sectors, through national economies to the global economy. Analysis of consumption patterns relates resource use to the environmental, social and economic impacts at the scale or context under investigation. The ideas of embodied resource use (the total resources needed to produce a product or service), resource intensity (the resources needed for each dollar spent on a good or service), and resource productivity (the amount of good or service produced for a given input of resource) are important tools for understanding the impacts of consumption with simple key resource categories indicating human needs being food, energy, materials and water.

Energy, water, food

Energy

Main article: Sustainable energy

Flow of CO₂ in an ecosystem

The Sun's energy, stored by plants (primary producers) during photosynthesis, passes through the food chain to other organisms to ultimately power all living processes. Since the industrial revolution the concentrated energy of the Sun stored in fossilized plants as fossil fuels has been a major driver of technology which, in turn, has been the source of both economic and political power. In 2007 climate scientists of the IPCC concluded that there was at least a 90% probability that atmospheric increase in CO₂ was human-induced, mostly as a result of fossil fuel emissions but, to a lesser extent from changes in land use. Stabilize the world’s climate will require high income countries to reduce their emissions by 60-90% over 2006 levels by 2050 which should hold CO₂ levels at 450-650 ppm from current levels of about 380 ppm. Above this level and temperatures could rise by more than 2 °C (36 °F) to produce “catastrophic” climate change. Reduction of current CO₂ levels must be achieved against a background of global population increase and developing countries aspiring to energy-intensive high consumption Western lifestyles.

Reducing greenhouse emissions, referred to as decarbonization, is being tackled at all scales, ranging from tracking the passage of carbon through the carbon cycle to the exploration of renewable energies, developing less carbon-hungry technology and transport systems and attempts by individuals to lead carbon neutral lifestyles by monitoring the fossil fuel use embodied in all the goods and services they use.

Water

Further information: Water resources

Water security and food security are inextricably linked. In the decade 1951-60 human water withdrawals were four times greater than the previous decade. This rapid increase resulted from scientific and technological developments impacting through the economy - especially the increase in irrigated land, growth in industrial and power sectors, and intensive dam construction on all continents. This altered the water cycle of rivers and lakes, affected their water quality and had a significant impact on the global water cycle. Currently towards 35% of human water use is unsustainable, drawing on diminishing aquifers and reducing the flows of major rivers: this percentage is likely to increase if climate change worsens, populations increase, aquifers become progressively depleted and supplies become polluted and unsanitary. From 1961 to 2001 water demand doubled - agricultural use increased by 75%, industrial use by more than 200%, and domestic use more than 400%. Humans currently use 40-50% of the globally available freshwater in the approximate proportion of 70% for agriculture, 22% for industry, and 8% for domestic purposes and the total volume is progressively increasing.

Water efficiency is being improved on a global scale by increased demand management, improved infrastructure, improved water productivity of agriculture, minimising the water intensity (embodied water) of goods and services, addressing shortages in the non-industrialised world, concentrating food production in areas of high productivity; and planning for climate change. At the local level people are becoming more water-self-sufficient by harvesting rainwater and reducing use of mains water.

Food

Further information: Food and Food security

The American Public Health Association (APHA) defines a "sustainable food system" as "one that provides healthy food to meet current food needs while maintaining healthy ecosystems that can also provide food for generations to come with minimal negative impact to the environment. A sustainable food system also encourages local production and distribution infrastructures and makes nutritious food available, accessible, and affordable to all. Further, it is humane and just, protecting farmers and other workers, consumers, and communities." Concerns about the environmental impacts of agribusiness and the stark contrast between the obesity problems of the Western world and the poverty and food insecurity of the developing world have generated a strong movement towards healthy, sustainable eating as a major component of overall ethical consumerism. The environmental effects of different dietary patterns depend on many factors, including the proportion of animal and plant foods consumed and the method of food production. The World Health Organization has published a Global Strategy on Diet, Physical Activity and Health which was endorsed by the May 2004 World Health Assembly. It recommends the Mediterranean diet which is associated with health and longevity and is low in meat, rich in fruits and vegetables, low in added sugar and limited salt, and low in saturated fatty acids; the traditional source of fat in the Mediterranean is olive oil, rich in monounsaturated fat. The healthy rice-based Japanese diet is also high in carbohydrates and low in fat. Both diets are low in meat and saturated fats and high in legumes and other vegetables; they are associated with a low incidence of ailments and low environmental impact.

At the global level the environmental impact of agribusiness is being addressed through sustainable agriculture and organic farming. At the local level there are various movements working towards local food production, more productive use of urban wastelands and domestic gardens including permaculture, urban horticulture, local food, slow food, sustainable gardening, and organic gardening.

Materials, toxic substances, waste

As global population and affluence increases, so does the use of materials which has increased in volume, diversity and distance transported. Included here are raw materials, minerals, synthetic chemicals (including hazardous substances), manufactured products, food, living organisms and waste.

Materials

Further information: Dematerialization

Sustainable use of materials has targeted the idea of dematerialization, converting the linear path of materials (extraction, use, disposal in landfill) to a circular material flow that reuses materials as much as possible, much like the cycling and reuse of waste in nature. This approach is supported by product stewardship and the increasing use of material flow analysis at all levels, especially individual countries and the global economy.

Toxic substances

Further information: Dangerous goods

Synthetic chemical production has escalated following the stimulus it received during the second World War. Chemical production includes everything from herbicides, pesticides and fertilizers to domestic chemicals and hazardous substances. Apart from the build-up of greenhouse gas emissions in the atmosphere, chemicals of particular concern include: heavy metals, nuclear waste, chlorofluorocarbons, persistent organic pollutants and all harmful chemicals capable of bioaccumulation. Although most synthetic chemicals are harmless there needs to be rigorous testing of new chemicals, in all countries, for adverse environmental and health effects. International legislation has been established to deal with the global distribution and management of dangerous goods.

The waste hierarchy

Waste

Further information: Waste management

Every economic activity produces material that can be classified as waste. The average human uses 45-85 tonnes of materials each year. To reduce waste industry, business and government are now mimicking nature by turning the waste produced by industrial metabolism into resource. Dematerialization is being encouraged through the ideas of industrial ecology, ecodesign and ecolabelling (see side bar). In addition to the well-established “reduce, reuse and recycle” shoppers are using their purchasing power for ethical consumerism.

Economic dimension

Further information: Ecological economics and Environmental economics

The Great Fish Market, painted by Jan Brueghel the Elder

Sustainability interfaces with economics through the social and ecological consequences of economic activity. Sustainability economics represents: "... a broad interpretation of ecological economics where environmental and ecological variables and issues are basic but part of a multidimensional perspective. Social, cultural, health-related and monetary/financial aspects have to be integrated into the analysis." At present the average per capita consumption of people in the developing world is sustainable but population numbers are increasing and individuals are aspiring to high consumption Western lifestyles. The developed world population is only increasing slightly but consumption levels are unsustainable. The challenge for sustainability is to curb and manage Western consumption while raising the standard of living of the developing world without increasing its resource use and environmental impact. This must be done by using strategies and technology that break the link between, on the one hand, economic growth and on the other, environmental damage and resource depletion.

In addressing this issue several key areas have been targeted for economic analysis and reform: the environmental effects of unconstrained economic growth; the consequences of nature being treated as an economic externality; and the possibility of a more ethical economics that takes greater account of the social and environmental consequences of market behaviour.

Decoupling environmental degradation and economic growth

Further information: Ecological economics

International Recycle Symbol

In the second half of the 20th century world population doubled, food production tripled, energy use quadrupled, and overall economic activity quintupled. Historically there has been a close correlation between economic growth and environmental degradation: as communities grow, so the environment declines. This trend is clearly demonstrated on graphs of human population numbers, economic growth, and environmental indicators. Unsustainable economic growth has been starkly compared to the malignant growth of a cancer because it eats away at the Earth's ecosystem services which are its life-support system. There is concern that, unless resource use is checked, modern global civilization will follow the path of ancient civilizations that collapsed through overexploitation of their resource base. While conventional economics is concerned largely with economic growth and the efficient allocation of resources, ecological economics has the explicit goal of sustainable scale (rather than continual growth), fair distribution and efficient allocation, in that order. The World Business Council for Sustainable Development states that "business cannot succeed in societies that fail". Sustainability studies analyse ways to reduce (decouple) the amount of resource (e.g. water, energy, or materials) needed for the production, consumption and disposal of a unit of good or service whether this be achieved from improved economic management, product design, new technology etc. Ecological economics includes the study of societal metabolism, the throughput of resources that enter and exit the economic system in relation to environmental quality.

Nature as an economic externality

Further information: Ecosystem services

The economic importance of nature is indicated by the use of the expression ecosystem services to highlight the market relevance of an increasingly scarce natural world that can no longer be regarded as both unlimited and free. In general as a commodity or service becomes more scarce the price increases and this acts as a restraint that encourages frugality, technical innovation and alternative products. However, this only applies when the product or service falls within the market system. As ecosystem services are generally treated as economic externalities they are unpriced and therefore overused and degraded, a situation sometimes referred to as the Tragedy of the Commons.

One approach to this dilemma has been the attempt to "internalise" these "externalities" by using market strategies like ecotaxes and incentives, tradeable permits for carbon, water and nitrogen use etc., and the encouragement of payment for ecosystem services. Community currencies such as LETS, a gift economy and Time Banking have also been promoted as a way of supporting local economies and the environment. Green economics is another market-based attempt to address issues of equity and the environment. The global recession and a range of government policies that have been connected to that, are likely to bring the biggest annual fall in the world's carbon dioxide emissions in 40 years.

Economic opportunity

Treating the environment as an externality may generate short-term profit at the expense of sustainability. Sustainable business practices, on the other hand, integrate ecological concerns with social and economic ones (i.e., the triple bottom line). Growth that depletes ecosystem services is sometimes termed "uneconomic growth" as it leads to a decline in quality of life. Minimising such growth can provide opportunities for local businesses. For example, industrial waste can be treated as an "economic resource in the wrong place". The benefits of waste reduction include savings from disposal costs, fewer environmental penalties, and reduced liability insurance. This may lead to increased market share due to an improved public image. Energy efficiency can also increase profits by reducing costs.

The idea of sustainability as a business opportunity has led to the formation of organizations such as the Sustainability Consortium of the Society for Organizational Learning, the Sustainable Business Institute, and the World Council for Sustainable Development. The expansion of sustainable business opportunities can contribute to job creation through the introduction of green-collar workers.

Social dimension

Further information: Social sustainability

Sustainability issues are generally expressed in scientific and environmental terms, but implementing change is a social challenge that entails, among other things, international and national law, urban planning and transport, local and individual lifestyles and ethical consumerism. "The relationship between human rights and human development, corporate power and environmental justice, global poverty and citizen action, suggest that responsible global citizenship is an inescapable element of what may at first glance seem to be simply matters of personal consumer and moral choice."

Peace, security, social justice

Further information: Peace and Social justice

Social disruptions like war, crime and corruption divert resources from areas of greatest human need, damage the capacity of societies to plan for the future, and generally threaten human well-being and the environment. Broad-based strategies for more sustainable social systems include: improved education and the political empowerment of women, especially in developing countries; greater regard for social justice notably equity between rich and poor both within and between countries; and intergenerational equity. Depletion of natural resources including fresh water increases the likelihood of “resource wars”. This aspect of sustainability has been referred to as environmental security and creates a clear need for global environmental agreements to manage resources such as aquifers and rivers which span political boundaries, and to protect global systems including oceans and the atmosphere.

Human settlements

One approach to sustainable living, exemplified by small-scale urban transition towns and rural ecovillages, seeks to create self-reliant communities based on principles of simple living, which maximise self-sufficiency particularly in food production. These principles, on a broader scale, underpin the concept of a bioregional economy. Other approaches, loosely based around new urbanism, are successfully reducing environmental impacts by altering the built environment to create and preserve sustainable cities which support sustainable transport. Residents in compact urban neighbourhoods drive fewer miles, and have significantly lower environmental impacts across a range of measures, compared with those living in sprawling suburbs.

Ultimately, the degree of human progress towards sustainability will depend on large scale social movements which influence both community choices and the built environment. Eco-municipalities may be one such movement. Eco-municipalities take a systems approach, based on sustainability principles. The eco-municipality movement is participatory, involving community members in a bottom-up approach. In Sweden, more than 70 cities and towns — 25 per cent of all municipalities in the country — have adopted a common set of "Sustainability Principles" and implemented these systematically throughout their municipal operations. There are now twelve eco-municipalities in the United States and the American Planning Association has adopted sustainability objectives based on the same principles.

Human relationship to nature

Sustainability principles

1. Reduce dependence upon fossil fuels,
underground metals, and minerals
2. Reduce dependence upon synthetic chemicals
and other unnatural substances
3. Reduce encroachment upon nature
4. Meet human needs fairly & efficiently

According to Murray Bookchin, the idea that humans must dominate nature is common in hierarchical societies. Bookchin contends that capitalism and market relationships, if unchecked, have the capacity to reduce the planet to a mere resource to be exploited. Nature is thus treated as a commodity: “The plundering of the human spirit by the market place is paralleled by the plundering of the earth by capital.” Still more basically, Bookchin argued that most of the activities that consume energy and destroy the environment are senseless because they contribute little to quality of life and well being. The function of work is to legitimse, even create, hierarchy. For this reason understanding the transformation of organic into hierarchical societies is crucial to finding a way forward.

Social ecology, founded by Bookchin, is based on the conviction that nearly all of humanity's present ecological problems originate in, indeed are mere symptoms of, dysfunctional social arrangements. Whereas most authors proceed as if our ecological problems can be fixed by implementing recommendations which stem from physical, biological, economic etc studies, Bookchin's claim is that these problems can only be resolved by understanding the underlying social processes and intervening in those processes by applying the concepts and methods of the social sciences.

Deep ecology establishes principles for the well-being of all life on Earth and the richness and diversity of life forms. This is only compatible with a substantial decrease of the human population and the end of human interference with the nonhuman world. To achieve this, deep ecologists advocate policies for basic economic, technological, and ideological structures that will improve the quality of life rather than the standard of living . Those who subscribe to these principles are obliged to make the necessary change happen.

Transition

Further information: Sociocultural evolution

Old and new approaches to human use of the atmosphere

The earth has a finite capacity to provide resources and to absorb waste, and human demands already exceed that capacity. Current lifestyles in the developed world, to which many people in the developing world also aspire, rely on depleting natural capital and are unsustainable. The United Nations has stated, in the Millennium Declaration, that "current unsustainable patterns of production and consumption must be changed". Yet weight of information and scientific evidence is often insufficient to produce necessary social change, especially if that change entails moving people out of their comfort zones.

There is a wealth of advice available to individuals wishing to reduce their personal impact on the environment through small, cheap and easily achievable steps. But the transition required to reduce global human consumption to within sustainable limits involves much larger changes, at all levels and contexts of society. The United Nations have recognised the central role of education, and have declared a decade of education for sustainable development, 2005-2014, which aims to "challenge us all to adopt new behaviours and practices to secure our future". The Worldwide Fund for Nature proposes a strategy for sustainability that goes beyond education to tackle underlying individualistic and materialistic societal values head-on and strengthen people's connections with the natural world. The level of change required to safeguard the life-supporting capacity of the Earth sets new challenges for community and political structures.

See also

{{{inline}}}

• Outline of sustainability
• List of sustainability topics
• Environmental issue

Further reading

• Adams, W. M. and Jeanrenaud, S. J. (2008). Transition to Sustainability: Towards a Humane and Diverse World. Gland, Switzerland: IUCN. 108 pp. ISBN 9782831710723. Retrieved on: 2009-07-06.
• Atkinson, G., Dietz, S. & Neumayer, E. (2007). Handbook of Sustainable Development. Cheltenham: Edward Elgar. ISBN 9781843765776.
• Bartlett, A. (1998). Reflections on Sustainability, Population Growth, and the Environment—Revisited revised version (January 1998) paper first published in Population & Environment 16(1): 5–35. Retrieved on: 2009-03-12.* Benyus, J. (1997). Biomimicry: Innovations Inspired by Nature. New York: William Morrow. ISBN 0060533226.
• Blackburn, W.R. (2007). The Sustainability Handbook. London: Earthscan. ISBN 9781844074952.
• Costanza, R., Graumlich, L.J. & Steffen, W. (eds), (2007). Sustainability or Collapse? An Integrated History and Future of People on Earth. Cambridge, MA.: MIT Press. ISBN 9780262033664.
• Norton, B. (2005). Sustainability, A Philosophy of Adaptive Ecosystem Management. Chicago: The University of Chicago Press. ISBN 9780226595214.

External links

• Breaking news in sustainability at Microdocs
• Compilation of Fact Sheets Published by the University of Michigan's Center for Sustainable Systems
• Elements of sustainability at Microdocs
• Learning for sustainability
• Roadmap for a Sustainable Earth on-line book by Hiroshi Komiyama and Steven Kraines
• Template:Dmoz
• Sustainable Food Guidelines published by Sustain: The alliance for better food and farming (UK)