Sustainability is the process of maintaining change in a balanced environment, in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional change are all in harmony and enhance both current and future potential to meet human needs and aspirations. For many in the field, sustainability is defined through the following interconnected domains or pillars: environment and social, which according to Fritjof Capra is based on the principles of Systems Thinking. Sub-domains of sustainable development have been considered also: cultural and political. While sustainable development may be the organizing principle for sustainability for some, for others, the two terms are paradoxical. Sustainable development is the development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Brundtland Report for the World Commission on Environment and Development introduced the term of sustainable development.
Sustainability can be defined as a socio-ecological process characterized by the pursuit of a common ideal. An ideal is by definition unattainable in space. However, by persistently and dynamically approaching it, the process results in a sustainable system. Healthy ecosystems and environments are necessary to the survival of other organisms. Ways of reducing negative human impact are environmentally-friendly chemical engineering, environmental resources management and environmental protection. Information is gained from green computing, green chemistry, earth science, environmental science and conservation biology. Ecological economics studies the fields of academic research that aim to address human economies and natural ecosystems. Moving towards sustainability is a social challenge that entails international and national law, urban planning and transport, supply chain management and individual lifestyles and ethical consumerism. Ways of living more sustainably can take many forms from reorganizing living conditions, reappraising economic sectors, or work practices, using science to develop new technologies, or designing systems in a flexible and reversible manner, adjusting individual lifestyles that conserve natural resources."The term'sustainability' should be viewed as humanity's target goal of human-ecosystem equilibrium, while'sustainable development' refers to the holistic approach and temporal processes that lead us to the end point of sustainability."
Despite the increased popularity of the use of the term "sustainability", the possibility that human societies will achieve environmental sustainability has been, continues to be, questioned—in light of environmental degradation, climate change, population growth and societies' pursuit of unlimited economic growth in a closed system. The name sustainability is derived from the Latin sustinere. Sustain can mean "maintain", "support", or "endure". Since the 1980s sustainability has been used more in the sense of human sustainability on planet Earth and this has resulted in the most quoted definition of sustainability as a part of the concept sustainable development, that of the Brundtland Commission of the United Nations on March 20, 1987: "sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs"; the 2005 World Summit on Social Development identified sustainable development goals, such as economic development, social development and environmental protection.
This view has been expressed as an illustration using three overlapping ellipses indicating that the three pillars of sustainability are not mutually exclusive and can be mutually reinforcing. In fact, the three pillars are interdependent, in the long run none can exist without the others; the three pillars have served as a common ground for numerous sustainability standards and certification systems in recent years, in particular in the food industry. Standards which today explicitly refer to the triple bottom line include Rainforest Alliance, Fairtrade and UTZ Certified; some sustainability experts and practitioners have illustrated four pillars of sustainability, or a quadruple bottom line. One such pillar is future generations, which emphasizes the long-term thinking associated with sustainability. There is an opinion that considers resource use and financial sustainability as two additional pillars of sustainability. Sustainable development consists of balancing local and global efforts to meet basic human needs without destroying or degrading the natural environment.
The question becomes how to represent the relationship between those needs and the environment. A study from 2005 pointed out. Ecological economist Herman Daly asked, "what use is a sawmill without a forest?" From this perspective, the economy is a subsystem of human society, itself a subsystem of the biosphere, a gain in one sector is a loss from another. This perspective led to the nested circles figure of'economics' inside'society' inside the'environment'; the simple definition that sustainability is something that improves "the quality of human life while living within the carrying capacity of supporting eco-systems", though vague, conveys the idea of sustainability having quantifiable limits. But sustainability is a call to action, a task in progress or "journe
Tidal power or tidal energy is a form of hydropower that converts the energy obtained from tides into useful forms of power electricity. Although not yet used, tidal energy has potential for future electricity generation. Tides are more predictable than the sun. Among sources of renewable energy, tidal energy has traditionally suffered from high cost and limited availability of sites with sufficiently high tidal ranges or flow velocities, thus constricting its total availability. However, many recent technological developments and improvements, both in design and turbine technology, indicate that the total availability of tidal power may be much higher than assumed, that economic and environmental costs may be brought down to competitive levels. Tide mills have been used both in Europe and on the Atlantic coast of North America; the incoming water was contained in large storage ponds, as the tide went out, it turned waterwheels that used the mechanical power it produced to mill grain. The earliest occurrences date from the Middle Ages, or from Roman times.
The process of using falling water and spinning turbines to create electricity was introduced in the U. S. and Europe in the 19th century. The world's first large-scale tidal power plant was the Rance Tidal Power Station in France, which became operational in 1966, it was the largest tidal power station in terms of output until Sihwa Lake Tidal Power Station opened in South Korea in August 2011. The Sihwa station uses sea wall defense barriers complete with 10 turbines generating 254 MW. Tidal power is taken from the Earth's oceanic tides. Tidal forces are periodic variations in gravitational attraction exerted by celestial bodies; these forces create corresponding currents in the world's oceans. Due to the strong attraction to the oceans, a bulge in the water level is created, causing a temporary increase in sea level; as the Earth rotates, this bulge of ocean water meets the shallow water adjacent to the shoreline and creates a tide. This occurrence takes place in an unfailing manner, due to the consistent pattern of the moon's orbit around the earth.
The magnitude and character of this motion reflects the changing positions of the Moon and Sun relative to the Earth, the effects of Earth's rotation, local geography of the sea floor and coastlines. Tidal power is the only technology that draws on energy inherent in the orbital characteristics of the Earth–Moon system, to a lesser extent in the Earth–Sun system. Other natural energies exploited by human technology originate directly or indirectly with the Sun, including fossil fuel, conventional hydroelectric, biofuel and solar energy. Nuclear energy makes use of Earth's mineral deposits of fissionable elements, while geothermal power utilizes the Earth's internal heat, which comes from a combination of residual heat from planetary accretion and heat produced through radioactive decay. A tidal generator converts the energy of tidal flows into electricity. Greater tidal variation and higher tidal current velocities can increase the potential of a site for tidal electricity generation; because the Earth's tides are due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is inexhaustible and classified as a renewable energy resource.
Movement of tides causes a loss of mechanical energy in the Earth–Moon system: this is a result of pumping of water through natural restrictions around coastlines and consequent viscous dissipation at the seabed and in turbulence. This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since its formation. During the last 620 million years the period of rotation of the earth has increased from 21.9 hours to 24 hours. While tidal power will take additional energy from the system, the effect is negligible and would only be noticed over millions of years. Tidal power can be classified into four generating methods: Tidal stream generators make use of the kinetic energy of moving water to power turbines, in a similar way to wind turbines that use wind to power turbines; some tidal generators can be built into the structures of existing bridges or are submersed, thus avoiding concerns over impact on the natural landscape. Land constrictions such as straits or inlets can create high velocities at specific sites, which can be captured with the use of turbines.
These turbines can be horizontal, open, or ducted. Stream energy can be used at a much higher rate than wind turbines due to water being more dense than air. Using similar technology to wind turbines converting energy in tidal energy is much more efficient. Close to 10 mph ocean tidal current would have an energy output equal or greater than a 90 mph wind speed for the same size of turbine system. Tidal barrages make use of the potential energy in the difference in height between high and low tides; when using tidal barrages to generate power, the potential energy from a tide is seized through strategic placement of specialized dams. When the sea level rises and the tide begins to come in, the temporary increase in tidal power is channeled into a large basin behind the dam, holding a large amount of potential energy. With the receding tide, this energy is converted into mechanical energy as the water is released through large turbines that create electrical power through the use of generators.
Barrages are dams across the full width of a tidal estuary. Dynamic tidal power is an untried but promising technology t
Recycling is the process of converting waste materials into new materials and objects. It is an alternative to "conventional" waste disposal that can save material and help lower greenhouse gas emissions. Recycling can prevent the waste of useful materials and reduce the consumption of fresh raw materials, thereby reducing: energy usage, air pollution, water pollution. Recycling is a key component of modern waste reduction and is the third component of the "Reduce and Recycle" waste hierarchy. Thus, recycling aims at environmental sustainability by substituting raw material inputs into and redirecting waste outputs out of the economic system. There are some ISO standards related to recycling such as ISO 15270:2008 for plastics waste and ISO 14001:2015 for environmental management control of recycling practice. Recyclable materials include many kinds of glass, cardboard, plastic, textiles and electronics; the composting or other reuse of biodegradable waste—such as food or garden waste—is a form of recycling.
Materials to be recycled are either delivered to a household recycling center or picked up from curbside bins sorted and reprocessed into new materials destined for manufacturing new products. In the strictest sense, recycling of a material would produce a fresh supply of the same material—for example, used office paper would be converted into new office paper or used polystyrene foam into new polystyrene. However, this is difficult or too expensive, so "recycling" of many products or materials involves their reuse in producing different materials instead. Another form of recycling is the salvage of certain materials from complex products, either due to their intrinsic value, or due to their hazardous nature. Recycling has been a common practice for most of human history, with recorded advocates as far back as Plato in the fourth century BC. During periods when resources were scarce and hard to come by, archaeological studies of ancient waste dumps show less household waste —implying more waste was being recycled in the absence of new material.
In pre-industrial times, there is evidence of scrap bronze and other metals being collected in Europe and melted down for perpetual reuse. Paper recycling was first recorded in 1031. In Britain dust and ash from wood and coal fires was collected by "dustmen" and downcycled as a base material used in brick making; the main driver for these types of recycling was the economic advantage of obtaining recycled feedstock instead of acquiring virgin material, as well as a lack of public waste removal in more densely populated areas. In 1813, Benjamin Law developed the process of turning rags into "shoddy" and "mungo" wool in Batley, Yorkshire; this material combined recycled fibers with virgin wool. The West Yorkshire shoddy industry in towns such as Batley and Dewsbury lasted from the early 19th century to at least 1914. Industrialization spurred demand for affordable materials. Railroads both purchased and sold scrap metal in the 19th century, the growing steel and automobile industries purchased scrap in the early 20th century.
Many secondary goods were collected and sold by peddlers who scoured dumps and city streets for discarded machinery, pots and other sources of metal. By World War I, thousands of such peddlers roamed the streets of American cities, taking advantage of market forces to recycle post-consumer materials back into industrial production. Beverage bottles were recycled with a refundable deposit at some drink manufacturers in Great Britain and Ireland around 1800, notably Schweppes. An official recycling system with refundable deposits was established in Sweden for bottles in 1884 and aluminum beverage cans in 1982. New chemical industries created in the late 19th century both invented new materials and promised to transform valueless into valuable materials. Proverbially, you could not make a silk purse of a sow's ear—until the US firm Arthur D. Little published in 1921 "On the Making of Silk Purses from Sows' Ears", its research proving that when "chemistry puts on overalls and gets down to business... new values appear.
New and better paths are opened to reach the goals desired."Recycling was a major issue for governments throughout World War II. Financial constraints and significant material shortages due to war efforts made it necessary for countries to reuse goods and recycle materials; these resource shortages caused by the world wars, other such world-changing occurrences encouraged recycling. The struggles of war claimed much of the material resources available, leaving little for the civilian population, it became necessary for most homes to recycle their waste, as recycling offered an extra source of materials allowing people to make the most of what was available to them. Recycling household materials meant a better chance of victory. Massive government promotion campaigns, such as the National Salvage Campaign in Britain and the Salvage for Victory campaign in the United States, were carried out on the home front in every combative nation, urging citizens to donate metal, rags, r
Air quality index
An air quality index is used by government agencies to communicate to the public how polluted the air is or how polluted it is forecast to become. As the AQI increases, an large percentage of the population is to experience severe adverse health effects. Different countries have their own air quality indices, corresponding to different national air quality standards; some of these are the Air Quality Health Index, the Air Pollution Index, the Pollutant Standards Index. Computation of the AQI requires an air pollutant concentration over a specified averaging period, obtained from an air monitor or model. Taken together and time represent the dose of the air pollutant. Health effects corresponding to a given dose are established by epidemiological research. Air pollutants vary in potency, the function used to convert from air pollutant concentration to AQI varies by pollutant, its air quality index values are grouped into ranges. Each range is assigned a descriptor, a color code, a standardized public health advisory.
The AQI can increase due to an increase of air emissions or from a lack of dilution of air pollutants. Stagnant air caused by an anticyclone, temperature inversion, or low wind speeds lets air pollution remain in a local area, leading to high concentrations of pollutants, chemical reactions between air contaminants and hazy conditions. On a day when the AQI is predicted to be elevated due to fine particle pollution, an agency or public health organization might: advise sensitive groups, such as the elderly and those with respiratory or cardiovascular problems to avoid outdoor exertion. Declare an "action day" to encourage voluntary measures to reduce air emissions, such as using public transportation. Recommend the use of masks to keep fine particles from entering the lungsDuring a period of poor air quality, such as an air pollution episode, when the AQI indicates that acute exposure may cause significant harm to the public health, agencies may invoke emergency plans that allow them to order major emitters to curtail emissions until the hazardous conditions abate.
Most air contaminants do not have an associated AQI. Many countries monitor ground-level ozone, sulfur dioxide, carbon monoxide and nitrogen dioxide, calculate air quality indices for these pollutants; the definition of the AQI in a particular nation reflects the discourse surrounding the development of national air quality standards in that nation. A website allowing government agencies anywhere in the world to submit their real-time air monitoring data for display using a common definition of the air quality index has become available. Air quality in Canada has been reported for many years with provincial Air Quality Indices. AQI values reflect air quality management objectives, which are based on the lowest achievable emissions rate, not concern for human health; the Air Quality Health Index or is a scale designed to help understand the impact of air quality on health. It is a health protection tool used to make decisions to reduce short-term exposure to air pollution by adjusting activity levels during increased levels of air pollution.
The Air Quality Health Index provides advice on how to improve air quality by proposing behavioural change to reduce the environmental footprint. This index pays particular attention to people, it provides them with advice on how to protect their health during air quality levels associated with low, moderate and high health risks. The Air Quality Health Index provides a number from 1 to 10+ to indicate the level of health risk associated with local air quality. On occasion, when the amount of air pollution is abnormally high, the number may exceed 10; the AQHI provides a local air quality current value as well as a local air quality maximums forecast for today and tomorrow, provides associated health advice. On December 30, 2013 Hong Kong replaced the Air Pollution Index with a new index called the Air Quality Health Index; this index, reported by the Environmental Protection Department, is measured on a scale of 1 to 10+ and considers four air pollutants: ozone. For any given hour the AQHI is calculated from the sum of the percentage excess risk of daily hospital admissions attributable to the 3-hour moving average concentrations of these four pollutants.
The AQHIs are grouped into five AQHI health risk categories with health advice provided: Each of the health risk categories has advice with it. At the low and moderate levels the public are advised. For the high category, the elderly and people with heart or respiratory illnesses are advising to reduce outdoor physical exertion. Above this the general public are advised to reduce or avoid outdoor physical exertion. China's Ministry of Environmental Protection is responsible for measuring the level of air pollution in China; as of January 1, 2013, MEP monitors daily pollution level in 163 of its major cities. The AQI level is based on the level of six atmospheric pollutants, namely sulfur dioxide, nitrogen dioxide, suspended particulates smaller than 10 μm in aerodynamic diameter, suspended particulates smaller than 2.5 μm in aerodynamic diameter ，carbon monoxide, ozone measured at the monitoring stations throughout each city. AQI MechanicsAn individual score is assigned to each pollutant and the fi
Emissions trading is a market-based approach to controlling pollution by providing economic incentives for achieving reductions in the emissions of pollutants. A central authority allocates or sells a limited number of permits to discharge specific quantities of a specific pollutant per time period. Polluters are required to hold permits in amount equal to their emissions. Polluters that want to increase their emissions must buy permits from others willing to sell them. Financial derivatives of permits can be traded on secondary markets. Various countries and groups of companies have adopted such trading systems, notably for mitigating climate change. In contrast to command-and-control environmental regulations such as best available technology standards and government subsidies and trade programs are a type of flexible environmental regulation that allows organizations to decide how best to meet policy targets. There are active trading programs in several air pollutants. For greenhouse gases, which cause climate change, permit units are called carbon credits.
The largest greenhouse gases trading program is the European Union Emission Trading Scheme, which trades in European Union Allowances. The United States has a national market to reduce acid rain and several regional markets in nitrogen oxides. Recent reduction in California's GHG emissions are not attributed to carbon trading but to other factors such as renewable portfolio standards and energy efficiency policies. GHG emissions increased at more than half of industrial point sources regulated by California's cap and trade program from 2013 to 2015. In theory, polluters who can reduce emissions most cheaply will do so, achieving the emission reduction at the lowest cost to society. Cap and trade is meant to provide the private sector with the flexibility required to reduce emissions while stimulating technological innovation and economic growth. In practice the theory can fall short. Environmental hotspots arise and impact areas nearest pollution sources when credits are purchased in lieu of emission reductions.
In addition to environmental justice issues cap and trade policy is not as effective as performance standards for reducing air pollutant emissions. For example, sulfur dioxide emissions and acidic sulfate deposition decreased to a larger extent more in Europe than in the United States over similar time periods with Europe employing traditional control approaches compared to the U. S.' Subsidized market approach. Pollution is a prime example of a market externality. An externality is an effect of some activity on an entity, not party to a market transaction related to that activity. Emissions trading is a market-based approach to address pollution; the overall goal of an emissions trading plan is to minimize the cost of meeting a set emissions target. In an emissions trading system, the government sets an overall limit on emissions, defines permits, or limited authorizations to emit, up to the level of the overall limit; the government may sell the permits, but in many existing schemes, it gives permits to participants equal to each participant's baseline emissions.
The baseline is determined by reference to the participant's historical emissions. To demonstrate compliance, a participant must hold permits at least equal to the quantity of pollution it emitted during the time period. If every participant complies, the total pollution emitted will be at most equal to the sum of individual limits; because permits can be bought and sold, a participant can choose either to use its permits exactly. In effect, the buyer pays a charge for polluting, while the seller gains a reward for having reduced emissions. In many schemes, organizations which do not pollute may trade permits and financial derivatives of permits. In some schemes, participants can bank allowances to use in future periods. In some schemes, a proportion of all traded permits must be retired periodically, causing a net reduction in emissions over time. Thus, environmental groups may buy and retire permits, driving up the price of the remaining permits according to the law of demand. In most schemes, permit owners can receive a tax deduction.
The government lowers the overall limit over time, with an aim towards a national emissions reduction target. According to the Environmental Defense Fund, cap-and-trade is the most environmentally and economically sensible approach to controlling greenhouse gas emissions, the primary cause of global warming, because it sets a limit on emissions, the trading encourages companies to innovate in order to emit less."International trade can offer a range of positive and negative incentives to promote international cooperation on climate change. Three issues are key to developing constructive relationships between international trade and climate agreements: how existing trade policies and rules can be modified to be more climate friendly.
Atmosphere of Earth
The atmosphere of Earth is the layer of gases known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention, reducing temperature extremes between day and night. By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, small amounts of other gases. Air contains a variable amount of water vapor, on average around 1% at sea level, 0.4% over the entire atmosphere. Air content and atmospheric pressure vary at different layers, air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in Earth's troposphere and in artificial atmospheres; the atmosphere has a mass of about 5.15×1018 kg, three quarters of, within about 11 km of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space.
The Kármán line, at 100 km, or 1.57% of Earth's radius, is used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km. Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition; the study of Earth's atmosphere and its processes is called atmospheric science. Early pioneers in the field include Richard Assmann; the three major constituents of Earth's atmosphere are nitrogen and argon. Water vapor accounts for 0.25% of the atmosphere by mass. The concentration of water vapor varies from around 10 ppm by volume in the coldest portions of the atmosphere to as much as 5% by volume in hot, humid air masses, concentrations of other atmospheric gases are quoted in terms of dry air; the remaining gases are referred to as trace gases, among which are the greenhouse gases, principally carbon dioxide, nitrous oxide, ozone. Filtered air includes trace amounts of many other chemical compounds.
Many substances of natural origin may be present in locally and seasonally variable small amounts as aerosols in an unfiltered air sample, including dust of mineral and organic composition and spores, sea spray, volcanic ash. Various industrial pollutants may be present as gases or aerosols, such as chlorine, fluorine compounds and elemental mercury vapor. Sulfur compounds such as hydrogen sulfide and sulfur dioxide may be derived from natural sources or from industrial air pollution; the relative concentration of gases remains constant until about 10,000 m. In general, air pressure and density decrease with altitude in the atmosphere. However, temperature has a more complicated profile with altitude, may remain constant or increase with altitude in some regions; because the general pattern of the temperature/altitude profile is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. In this way, Earth's atmosphere can be divided into five main layers.
Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere and thermosphere. From highest to lowest, the five main layers are: Exosphere: 700 to 10,000 km Thermosphere: 80 to 700 km Mesosphere: 50 to 80 km Stratosphere: 12 to 50 km Troposphere: 0 to 12 km The exosphere is the outermost layer of Earth's atmosphere, it extends from the exobase, located at the top of the thermosphere at an altitude of about 700 km above sea level, to about 10,000 km where it merges into the solar wind. This layer is composed of low densities of hydrogen and several heavier molecules including nitrogen and carbon dioxide closer to the exobase; the atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another. Thus, the exosphere no longer behaves like a gas, the particles escape into space; these free-moving particles follow ballistic trajectories and may migrate in and out of the magnetosphere or the solar wind. The exosphere is located too far above Earth for any meteorological phenomena to be possible.
However, the aurora borealis and aurora australis sometimes occur in the lower part of the exosphere, where they overlap into the thermosphere. The exosphere contains most of the satellites orbiting Earth; the thermosphere is the second-highest layer of Earth's atmosphere. It extends from the mesopause at an altitude of about 80 km up to the thermopause at an altitude range of 500–1000 km; the height of the thermopause varies due to changes in solar activity. Because the thermopause lies at the lower boundary of the exosphere, it is referred to as the exobase; the lower part of the thermosphere, from 80 to 550 kilometres above Earth's surface, contains the ionosphere. The temperature of the thermosphere increases with height. Unlike the stratosphere beneath it, wherein a temperature inversion is due to the absorption of radiation by ozone, the inversion in the t
The term Peak coal is used to refer to the point in time at which coal production and consumption reaches its maximum, after which, it is assumed and consumption will decline steadily. The term was used in connection with M. King Hubbert's Hubbert peak theory, in which the finite nature of the resource determines a constraint on production. However, since the expansion of renewable energy in electricity generation, the term is now used with reference to a peak in coal demand, which may have occurred. According to M. King Hubbert's Hubbert peak theory, peak coal is the point in time at which the maximum global coal production rate is reached, after which, according to the theory, the rate of production will enter a terminal decline. Coal is a fossil fuel formed from plant matter over the course of millions of years, it thus considered to be a non-renewable energy source. There are two different possible peaks: one measured by another by energy output; the world average heat content per mass of mined coal rose from 8,020 BTU/lb. in 1989 to 9,060 BTU/lb. in 1999.
Since 1999, the world average heat content of mined coal has been steady, was 9,030 BTU/lb. in 2011. The estimates for global peak coal extraction vary wildly. Many coal associations suggest the peak could occur in 200 years or more, while scholarly estimates predict the peak to occur as soon as the immediate future. Research in 2009 by the University of Newcastle in Australia concluded that global coal extraction could peak sometime between the present and 2048. A 2007 study by the German Energy Watch Group predicted that global peak coal extraction may occur sometime around 2025 at 30 percent above the 2005 rate; the contemporary concept of peak coal follows from Hubbert peak theory, most associated with peak oil. Hubbert concluded that each oil nation has a bell-shaped depletion curve. However, this question was raised by William Stanley Jevons in his book The Coal Question in 1865. Hubbert noted that United States coal extraction grew exponentially at a steady 6.6% per year from 1850 to 1910.
The growth leveled off. He concluded. At some point, the rate of extraction will have to peak and decline until the resource is exhausted, he theorized that extraction rate plotted versus time would show a bell-shaped curve, declining as as it had risen. Hubbert used his observation of the US coal extraction to predict the behavior of peak oil; the Hubbert linearization using yearly production rates has weaknesses for peak coal calculation, as the signal-to-noise ratio is inferior with coal mining data compared to oil extraction. As a consequence, Rutledge uses cumulative production for linearization. By this method the estimated ultimate recovery results in a stable fit for active coal regions; the ultimate production for world coal is estimated to be 680 Gt, of which 309 Gt have been produced. However, in 2013 the World Coal Association reported that two different estimates of coal reserves remaining were 1038 and 861 Gt. Although reserves of coal remain abundant, consumption of coal has declined in many countries.
In 2016 Scotland closed its last coal-fired power plant. This decline has resulted from the replacement of coal-fired electricity by gas and renewable energy, along with the decline of the steel industry in some countries; as a result, the term "peak coal" is now used to refer to a peak and subsequent decline in global and national coal consumption. In 2016 experts estimated that China, the world's largest coal consumer, reached peak coal in 2013, that the world may have passed peak coal. However, in 2017, for the first time in four years, demand for coal rose; as of 2015, China accounted for 50.0 percent of world coal consumption. Chinese coal consumption fell in 2014 and 2015; the last previous decline in Chinese coal consumption had been in 1997 and 1998. While consumption in China and the United States declined in 2015, that of India continued to rise and, in 2015, India surpassed the United States and became the world's second-largest consumer of coal; as of 2011, the top coal-extracting countries were China, United States, India and Indonesia.
Four out of five of these largest coal-extracting countries, the exception being the United States, had experienced significant increases in coal extraction over the previous decade. The People's Republic of China is the world’s largest coal extractor and has the third largest reserves after Russia and the United States; the Energy Watch Group predicted that the Chinese extraction will peak around 2015 in their 2007 report, revised that to 2020 in their March 2013 report. The EWG predicts that the recent steep rise in extraction will be followed by a steep decline after 2020. Another study puts the peak at 2027; the US Energy Information Administration projects that China coal extraction will continue to rise until 2030. Although Hubbert's analysis in 1956 projected total extraction to peak in about 2150, records show that extraction reached an energy peak in 1998 and a tonnage peak in 2008. US coal extraction peaked during World War I declined during the depression years of the 1930s. Coal extraction peaked again in the 1940s declined during the 1950s.
Coal extraction revived, was on a nearly continual increasing trend from 1962 to 2008, exceeding the previous peaks. Extraction in 2008 was a record 1.17 billion short tons. High-BTU anthracite coal peaked in 1914. Bituminous coal extraction has been declining since 1990