Fugitive emission

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Fugitive emissions are leaks and other irregular releases of gases or vapors from a pressurized containment – such as appliances, storage tanks, pipelines, wells, or other pieces of equipment – mostly from industrial activities. In addition to the economic cost of lost commodities, fugitive emissions contribute to local air pollution and may cause further environmental harm. Common industrial gases include refrigerants and natural gas, while less common examples are perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride.

Contents

Most occurrences of fugitive emissions are small, of no immediate impact, and difficult to detect. Nevertheless due to rapidly expanding activity, even the most strictly regulated gases have accumulated outside of industrial workings to reach measurable levels globally. [1] Fugitive emissions include many poorly understood pathways by which the most potent and long-lived ozone depleting substances and greenhouse gases enter Earth's atmosphere. [2]

In particular, the build-up of a variety of man-made halogenated gases over the past several decades contributes more than 10% of the radiative forcing which drives global climate change as of year 2020. [3] Moreover, the ongoing banking of small to large quantities of these gases within consumer appliances, industrial systems, and abandoned equipment throughout the world has all but guaranteed their future emissions for many years to come. [4] Fugitive emissions of CFCs and HCFCs from legacy equipment and process uses have continued to hinder recovery of the stratospheric ozone layer in the years since most production was banned in accordance with the international Montreal Protocol. [5]

Similar legacy issues continue to be created at ever-increasing scale with the mining of fossil hydrocarbons, including gas venting and fugitive gas emissions from coal mines, oil wells, and gas wells. [6] Economically depleted mines and wells may be abandoned or poorly sealed, while properly decommissioned facilities may experience emission increases following equipment failures or earth disturbances. Satellite monitoring systems are beginning to be developed and deployed to aid identification of the largest emitters, sometimes known as super-emitters. [7] [8]

Emissions inventory

A detailed inventory of greenhouse gas emissions from upstream oil and gas activities in Canada for the year 2000 estimated that fugitive equipment leaks had a global warming potential equivalent to the release of 17 million metric tonnes of carbon dioxide, or 12 percent of all greenhouse gases emitted by the sector, [9] while another report put fugitive emissions at 5.2% of world greenhouse emissions in 2013. [10] Venting of natural gas, flaring, accidental releases and storage losses accounted for an additional 38 percent.[ citation needed ]

Fugitive emissions present other risks and hazards. Emissions of volatile organic compounds such as benzene from oil refineries and chemical plants pose a long term health risk to workers and local communities. In situations where large amounts of flammable liquids and gases are contained under pressure, leaks also increase the risk of fire and explosion.

Pressurized equipment

Leaks from pressurized process equipment generally occur through valves, pipe connections, mechanical seals, or related equipment. Fugitive emissions also occur at evaporative sources such as waste water treatment ponds and storage tanks. Because of the huge number of potential leak sources at large industrial facilities and the difficulties in detecting and repairing some leaks, fugitive emissions can be a significant proportion of total emissions. Though the quantities of leaked gases may be small, gases that have serious health or environmental impacts can cause a significant problem.

Fenceline monitoring

Fenceline monitoring techniques involve the use of samplers and detectors positioned at the fenceline of a facility. Several types of devices are used to provide data on a facility's fugitive emissions, including passive samplers with sorbent tubes, and "SPod" sensors that provide real-time data. [11]

Detection and repair

To minimize and control leaks at process facilities operators carry out regular leak detection and repair activities. Routine inspections of process equipment with gas detectors can be used to identify leaks and estimate the leak rate in order to decide on appropriate corrective action. Proper routine maintenance of equipment reduces the likelihood of leaks.

Because of the technical difficulties and costs of detecting and quantifying actual fugitive emissions at a site or facility, and the variability and intermittent nature of emission flow rates, bottom-up estimates based on standard emission factors are generally used for annual reporting purposes.

New technologies

New technologies are under development that could revolutionize the detection and monitoring of fugitive emissions. One technology, known as differential absorption lidar (DIAL), can be used to remotely measure concentration profiles of hydrocarbons in the atmosphere up to several hundred meters from a facility. DIAL has been used for refinery surveys in Europe for over 15 years. A pilot study carried out in 2005 using DIAL found that actual emissions at a refinery were fifteen times higher than those previously reported using the emission factor approach. The fugitive emissions were equivalent to 0.17% of the refinery throughput. [12]

Portable gas leak imaging cameras are also a new technology that can be used to improve leak detection and repair, leading to reduced fugitive emissions. The cameras use infrared imaging technology to produce video images in which invisible gases escaping from leak sources can be clearly identified.

Types

Natural gas

This section is an excerpt from Fugitive gas emissions.[ edit ]

Fugitive gas emissions are emissions of gas (typically natural gas, which contains methane) to atmosphere or groundwater [13] which result from oil and gas or coal mining activity. [14] In 2016, these emissions, when converted to their equivalent impact of carbon dioxide, accounted for 5.8% of all global greenhouse gas emissions. [14]

Most fugitive emissions are the result of loss of well integrity through poorly sealed well casings due to geochemically unstable cement. [15] This allows gas to escape through the well itself (known as surface casing vent flow) or via lateral migration along adjacent geological formations (known as gas migration). [15] Approximately 1-3% of methane leakage cases in unconventional oil and gas wells are caused by imperfect seals and deteriorating cement in wellbores. [15] Some leaks are also the result of leaks in equipment, intentional pressure release practices, or accidental releases during normal transportation, storage, and distribution activities. [16] [17] [18]

Emissions can be measured using either ground-based or airborne techniques. [15] [16] [19] In Canada, the oil and gas industry is thought to be the largest source of greenhouse gas and methane emissions, [20] and approximately 40% of Canada's emissions originate from Alberta. [17] Emissions are largely self-reported by companies. The Alberta Energy Regulator keeps a database on wells releasing fugitive gas emissions in Alberta, [21] and the British Columbia Oil and Gas Commission keeps a database of leaky wells in British Columbia. Testing wells at the time of drilling was not required in British Columbia until 2010, and since then 19% of new wells have reported leakage problems. This number may be a low estimate, as suggested by fieldwork completed by the David Suzuki Foundation. [13] Some studies have shown a range of 6-30% of wells suffer gas leakage. [19] [21] [22] [23]

Canada and Alberta have plans for policies to reduce emissions, which may help combat climate change. [24] [25] Costs related to reducing emissions are very location-dependent and can vary widely. [26] Methane has a greater global warming impact than carbon dioxide, as its radiative force is 120, 86 and 34 times that of carbon dioxide, when considering a 1, 20 and 100 year time frame (including Climate Carbon Feedback [27] [28] [21] Additionally, it leads to increases in carbon dioxide concentration through its oxidation by water vapor. [29]

See also

Related Research Articles

<span class="mw-page-title-main">Greenhouse effect</span> Atmospheric phenomenon causing planetary warming

The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly to space, resulting in a warmer planet. Earth's natural greenhouse effect makes life as we know it possible and carbon dioxide plays a significant role in providing for the relatively high temperature on Earth. The greenhouse effect is a process by which thermal radiation from a planetary atmosphere warms the planet's surface beyond the temperature it would have in the absence of its atmosphere. Without the greenhouse effect, the Earth's average surface temperature would be about −18 °C (−0.4 °F) compared to Earth's actual average surface temperature of approximately 14 °C (57.2 °F). In addition to the naturally present greenhouse gases, human-caused increases in greenhouse gases trap greater amounts of heat, causing the Earth to become warmer over time.

Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide. GWP is 1 for CO2. For other gases it depends on the gas and the time frame.

<span class="mw-page-title-main">Natural gas</span> Gaseous fossil fuel

Natural gas is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon dioxide, nitrogen, hydrogen sulfide, and helium are also usually present. Natural gas is colorless and odorless, so odorizers such as mercaptan are commonly added to natural gas supplies for safety so that leaks can be readily detected.

<span class="mw-page-title-main">Radiative forcing</span> Difference between solar irradiance absorbed by the Earth and energy radiated back to space

Radiative forcing is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured by watts / meter². It is a scientific concept used to quantify and compare the external drivers of change to Earth's energy balance. System feedbacks and internal variability are related concepts, encompassing other factors that also influence the direction and magnitude of imbalance.

<span class="mw-page-title-main">Emission intensity</span> Emission rate of a pollutant

An emission intensity is the emission rate of a given pollutant relative to the intensity of a specific activity, or an industrial production process; for example grams of carbon dioxide released per megajoule of energy produced, or the ratio of greenhouse gas emissions produced to gross domestic product (GDP). Emission intensities are used to derive estimates of air pollutant or greenhouse gas emissions based on the amount of fuel combusted, the number of animals in animal husbandry, on industrial production levels, distances traveled or similar activity data. Emission intensities may also be used to compare the environmental impact of different fuels or activities. In some case the related terms emission factor and carbon intensity are used interchangeably. The jargon used can be different, for different fields/industrial sectors; normally the term "carbon" excludes other pollutants, such as particulate emissions. One commonly used figure is carbon intensity per kilowatt-hour (CIPK), which is used to compare emissions from different sources of electrical power.

<span class="mw-page-title-main">Carbon tetrafluoride</span> Chemical compound

Tetrafluoromethane, also known as carbon tetrafluoride or R-14, is the simplest perfluorocarbon (CF4). As its IUPAC name indicates, tetrafluoromethane is the perfluorinated counterpart to the hydrocarbon methane. It can also be classified as a haloalkane or halomethane. Tetrafluoromethane is a useful refrigerant but also a potent greenhouse gas. It has a very high bond strength due to the nature of the carbon–fluorine bond.

<span class="mw-page-title-main">Greenhouse gas emissions</span> Sources and amounts of greenhouse gases emitted to the atmosphere from human activities

Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and large oil and gas companies. Human-caused emissions have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but have been consistent among all greenhouse gases (GHGs). Emissions in the 2010s averaged 56 billion tons a year, higher than any decade before. Each year, about 6.7 million people die from polluted air quality.

Carbon monitoring as part of greenhouse gas monitoring refers to tracking how much carbon dioxide or methane is produced by a particular activity at a particular time. For example, it may refer to tracking methane emissions from agriculture, or carbon dioxide emissions from land use changes, such as deforestation, or from burning fossil fuels, whether in a power plant, automobile, or other device. Because carbon dioxide is the greenhouse gas emitted in the largest quantities, and methane is an even more potent greenhouse gas, monitoring carbon emissions is widely seen as crucial to any effort to reduce emissions and thereby slow climate change.

<span class="mw-page-title-main">Low-carbon diet</span> Diet to reduce greenhouse gas emissions

A low-carbon diet refers to making lifestyle choices related to food consumption to reduce resulting greenhouse gas emissions (GHGe). Choosing a low carbon diet is one facet of developing sustainable diets which increase the long-term sustainability of humanity.

<span class="mw-page-title-main">Arctic methane emissions</span> Release of methane from seas and soils in permafrost regions of the Arctic

Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic. While it is a long-term natural process, methane release is exacerbated by global warming. This results in a positive feedback cycle, as methane is itself a powerful greenhouse gas.

<span class="mw-page-title-main">Greenhouse gas</span> Gas in an atmosphere that absorbs and emits radiation within the thermal infrared range

A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Without greenhouse gases, the average temperature of Earth's surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F). The atmospheres of Venus, Mars and Titan also contain greenhouse gases.

<span class="mw-page-title-main">Atmospheric methane</span> Methane present in Earths atmosphere

Atmospheric methane is the methane present in Earth's atmosphere. Atmospheric methane concentrations are of interest because it is one of the most potent greenhouse gases in Earth's atmosphere. Atmospheric methane is rising.

<span class="mw-page-title-main">Environmental impact of the petroleum industry</span>

The environmental impact of the petroleum industry is extensive and expansive due to petroleum having many uses. Crude oil and natural gas are primary energy and raw material sources that enable numerous aspects of modern daily life and the world economy. Their supply has grown quickly over the last 150 years to meet the demands of rapidly increasing human population, creativity, knowledge, and consumerism.

<span class="mw-page-title-main">Greenhouse gas monitoring</span> Measurement of greenhouse gas emissions and levels

Greenhouse gas monitoring is the direct measurement of greenhouse gas emissions and levels. There are several different methods of measuring carbon dioxide concentrations in the atmosphere, including infrared analyzing and manometry. Methane and nitrous oxide are measured by other instruments. Greenhouse gases are measured from space such as by the Orbiting Carbon Observatory and networks of ground stations such as the Integrated Carbon Observation System.

The atmospheric carbon cycle accounts for the exchange of gaseous carbon compounds, primarily carbon dioxide, between Earth's atmosphere, the oceans, and the terrestrial biosphere. It is one of the faster components of the planet's overall carbon cycle, supporting the exchange of more than 200 billion tons of carbon in and out of the atmosphere throughout the course of each year. Atmospheric concentrations of CO2 remain stable over longer timescales only when there exists a balance between these two flows. Methane, Carbon monoxide (CO), and other man-made compounds are present in smaller concentrations and are also part of the atmospheric carbon cycle.

Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% of methane released globally was from human activities, while natural sources contributed about 40%. Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.

<span class="mw-page-title-main">Gas venting</span> Disposal of unwanted methane gas from fossil fuels

Gas venting, more specifically known as natural-gas venting or methane venting, is the intentional and controlled release of gases containing alkane hydrocarbons - predominately methane - into earth's atmosphere. It is a widely used method for disposal of unwanted gases which are produced during the extraction of coal and crude oil. Such gases may lack value when they are not recyclable into the production process, have no export route to consumer markets, or are surplus to near-term demand. In cases where the gases have value to the producer, substantial amounts may also be vented from the equipment used for gas collection, transport, and distribution.

Fugitive gas emissions are emissions of gas to atmosphere or groundwater which result from oil and gas or coal mining activity. In 2016, these emissions, when converted to their equivalent impact of carbon dioxide, accounted for 5.8% of all global greenhouse gas emissions.

The Canadian province of Alberta faces a number of environmental issues related to natural resource extraction—including oil and gas industry with its oil sands—endangered species, melting glaciers in banff, floods and droughts, wildfires, and global climate change. While the oil and gas industries generates substantial economic wealth, the Athabasca oil sands, which are situated almost entirely in Alberta, are the "fourth most carbon intensive on the planet behind Algeria, Venezuela and Cameroon" according to an August 8, 2018 article in the American Association for the Advancement of Science's journal Science. This article details some of the environmental issues including past ecological disasters in Alberta and describes some of the efforts at the municipal, provincial and federal level to mitigate the risks and impacts.

Orphan, orphaned or abandoned wells are oil or gas wells that have been abandoned by fossil fuel extraction industries. These wells may have been deactivated because of economic viability, failure to transfer ownerships, or neglect and thus no longer have legal owners responsible for their care. Decommissioning wells effectively can be expensive, costing millions of dollars, and economic incentives for businesses generally encourage abandonment. This process leaves the wells the burden of government agencies or landowners when a business entity can no longer be held responsible. As climate change mitigation reduces demand and usage of oil and gas, its expected that more wells will be abandoned as stranded assets.

References

  1. ↑ "Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases". Washington, DC: United States Environmental Protection Agency (EPA). 2021-07-21.
  2. ↑ Thibault Laconde (2018). "Fugitive emissions: A blind spot in the fight against climate change". www.climate-chance.org. Retrieved 2021-02-24.
  3. ↑ Butler, James H.; Montzka, Stephen A. (Spring 2021). "The NOAA Annual Greenhouse Gas Index (AGGI)". Global Monitoring Laboratory/Earth System Research Laboratories. Boulder, CO: National Oceanic & Atmospheric Administration.
  4. ↑ Simmonds, P. G., Rigby, M., Manning, A. J., Park, S., Stanley, K. M., McCulloch, A., Henne, S., Graziosi, F., Maione, M., and 19 others (2020) "The increasing atmospheric burden of the greenhouse gas sulfur hexafluoride (SF6)". Atmos. Chem. Phys., 20: 7271–7290. doi : 10.5194/acp-20-7271-2020
  5. ↑ McGrath, Matt (2018-07-09). "China 'home foam' gas key to ozone mystery". BBC News. Retrieved 2021-02-24.
  6. ↑ "Methane Tracker - Analysis". International Energy Agency (Paris). 2019-11-01. Retrieved 2021-02-24.
  7. ↑ Michelle Lewis (2019-12-18). "New satellite technology reveals Ohio gas leak released 60K tons of methane". Electrek. Retrieved 2021-02-24.
  8. ↑ Fialka, John (2018-03-09). "Meet the satellite that can pinpoint methane and carbon dioxide leaks". Scientific American. Retrieved 2020-02-24.
  9. ↑ Clearstone Engineering (1994). "A National Inventory of Greenhouse Gas (GHG), Criteria Air Contaminant (CAC) and Hydrogen Sulphide (H2S) Emissions by the Upstream Oil and Gas Industry, Volume 1, Overview of the GHG Emissions Inventory". Canadian Association of Petroleum Producers: v. Retrieved 2008-12-10.{{cite journal}}: Cite journal requires |journal= (help)[ permanent dead link ]
  10. ↑ "Global Emissions". Arlington, VA: Center for Climate and Energy Solutions. 6 January 2020.
  11. ↑ "Fenceline Monitoring". EPA. 2018-05-11.
  12. ↑ Chambers, Allan; Tony Wootton; Jan Moncrieff; Philip McCready (August 2008). "Direct Measurement of Fugitive Emissions of Hydrocarbons from a Refinery". Journal of the Air & Waste Management Association. 58 (8): 1047–1056. doi: 10.3155/1047-3289.58.8.1047 . PMID   18720654. S2CID   1035294.
  13. 1 2 Wisen, Joshua; Chesnaux, Romain; Werring, John; Wendling, Gilles; Baudron, Paul; Barbecot, Florent (2017-10-01). "A Portrait of Oil and Gas Wellbore Leakage in Northeastern British Columbia, Canada". GeoOttawa2017.
  14. 1 2 Ritchie, Hannah; Roser, Max (11 May 2020). "Emissions by sector". Our World in Data. Retrieved 30 July 2021.
  15. 1 2 3 4 Cahill, Aaron G.; Steelman, Colby M.; Forde, Olenka; Kuloyo, Olukayode; Ruff, S. Emil; Mayer, Bernhard; Mayer, K. Ulrich; Strous, Marc; Ryan, M. Cathryn (27 March 2017). "Mobility and persistence of methane in groundwater in a controlled-release field experiment". Nature Geoscience. 10 (4): 289–294. Bibcode:2017NatGe..10..289C. doi:10.1038/ngeo2919. ISSN   1752-0908.
  16. 1 2 Caulton, Dana R.; Shepson, Paul B.; Santoro, Renee L.; Sparks, Jed P.; Howarth, Robert W.; Ingraffea, Anthony R.; Cambaliza, Maria O. L.; Sweeney, Colm; Karion, Anna (2014-04-29). "Toward a better understanding and quantification of methane emissions from shale gas development". Proceedings of the National Academy of Sciences. 111 (17): 6237–6242. Bibcode:2014PNAS..111.6237C. doi: 10.1073/pnas.1316546111 . ISSN   0027-8424. PMC   4035982 . PMID   24733927.
  17. 1 2 Lopez, M.; Sherwood, O.A.; Dlugokencky, E.J.; Kessler, R.; Giroux, L.; Worthy, D.E.J. (June 2017). "Isotopic signatures of anthropogenic CH 4 sources in Alberta, Canada". Atmospheric Environment. 164: 280–288. Bibcode:2017AtmEn.164..280L. doi: 10.1016/j.atmosenv.2017.06.021 .
  18. ↑ "ICF Methane Cost Curve Report". Environmental Defense Fund. March 2014. Retrieved 2018-03-17.
  19. 1 2 Atherton, Emmaline; Risk, David; Fougere, Chelsea; Lavoie, Martin; Marshall, Alex; Werring, John; Williams, James P.; Minions, Christina (2017). "Mobile measurement of methane emissions from natural gas developments in Northeastern British Columbia, Canada". Atmospheric Chemistry and Physics Discussions. 17 (20): 12405–12420. doi: 10.5194/acp-2017-109 .
  20. ↑ Johnson, Matthew R.; Tyner, David R.; Conley, Stephen; Schwietzke, Stefan; Zavala-Araiza, Daniel (2017-11-07). "Comparisons of Airborne Measurements and Inventory Estimates of Methane Emissions in the Alberta Upstream Oil and Gas Sector". Environmental Science & Technology. 51 (21): 13008–13017. Bibcode:2017EnST...5113008J. doi: 10.1021/acs.est.7b03525 . ISSN   0013-936X. PMID   29039181.
  21. 1 2 3 Bachu, Stefan (2017). "Analysis of gas leakage occurrence along wells in Alberta, Canada, from a GHG perspective – Gas migration outside well casing". International Journal of Greenhouse Gas Control. 61: 146–154. doi:10.1016/j.ijggc.2017.04.003.
  22. ↑ Boothroyd, I.M.; Almond, S.; Qassim, S.M.; Worrall, F.; Davies, R.J. (March 2016). "Fugitive emissions of methane from abandoned, decommissioned oil and gas wells". Science of the Total Environment. 547: 461–469. Bibcode:2016ScTEn.547..461B. doi: 10.1016/j.scitotenv.2015.12.096 . PMID   26822472.
  23. ↑ A. Ingraffea, R. Santoro, S. B. Shonkoff, Wellbore Integrity: Failure Mechanisms, Historical Record, and Rate Analysis. EPA’s Study Hydraul. Fract. Its Potential Impact Drink. Water Resour. 2013 Tech. Work. Present. Well Constr. Subsurf. Model. (2013) (available at http://www2.epa.gov/hfstudy/2013-technical-workshop-presentations-0)
  24. ↑ Alberta Government (2015). "Climate Leadership Plan" . Retrieved 2018-03-17.
  25. ↑ Pan-Canadian framework on clean growth and climate change : canada's plan to address climate change and grow the economy. Canada. Environment and Climate Change Canada. Gatineau, Québec. 2016. ISBN   9780660070230. OCLC   969538168.{{cite book}}: CS1 maint: others (link)
  26. ↑ Munnings, Clayton; Krupnick, Alan J. (2017-07-10). "Comparing Policies to Reduce Methane Emissions in the Natural Gas Sector". Resources for the Future. Retrieved 2018-03-17.
  27. ↑ Myhre, G.; Shindell, D.; Bréon, F.-M.; Collins, W.; et al. (2013). "Chapter 8: Anthropogenic and Natural Radiative Forcing" (PDF). IPCC AR5 WG1 2013 . pp. 659–740.
  28. ↑ Etminan, M.; Myhre, G.; Highwood, E. J.; Shine, K. P. (2016-12-28). "Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing". Geophysical Research Letters. 43 (24): 2016GL071930. Bibcode:2016GeoRL..4312614E. doi: 10.1002/2016GL071930 . ISSN   1944-8007.
  29. ↑ Myhre; Shindell; Bréon; Collins; Fuglestvedt; Huang; Koch; Lamarque; Lee; Mendoza; Nakajima; Robock; Stephens; Takemura; Zhang (2013). "Anthropogenic and Natural Radiative Forcing". In Stocker; Qin; Plattner; Tignor; Allen; Boschung; Nauels; Xia; Bex; Midgley (eds.). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.
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