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Peat gatherers at Westhay, Somerset Levels in 1905
Peat stacks and cutting at Westhay, Somerset Levels
Harvesting the peat at Westhay, Somerset Levels
Peat in Lewis, Scotland

Peat (turf) is an accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands or mires.<ref name=Joosten_Clarke2002>{{#invoke:citation/CS1|citation |CitationClass=report }}</ref><ref name=PERG2013>{{#invoke:citation/CS1|citation |CitationClass=report }}</ref> The peatland ecosystem is the most efficient carbon sink on the planet<ref name=PERG2013 /> because peatland plants capture the CO2 which is naturally released from the peat, thus maintaining an equilibrium. In natural peatlands, the "annual rate of biomass production is greater than the rate of decomposition", but it takes "thousands of years for peatlands to develop the deposits of 1.5 to 2.3 m, which is the average depth of the boreal peatlands".<ref name=PERG2013 /> One of the most common components is Sphagnum moss, although many other plants can contribute. Soils that contain mostly peat are known as histosols. Peat forms in wetland conditions, where flooding obstructs flows of oxygen from the atmosphere, slowing rates of decomposition.<ref>Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Chapter 1.</ref>

Peatlands, also known as mires,<ref group=Notes>"The term ‘peatland’ includes mires (Joosten and Clarke 2002)."</ref> particularly bogs, are the most important source of peat,<ref name="Gorham, E. 1957">Gorham, E. (1957). The development of peatlands. Quarterly Review of Biology, 32, 145–66.</ref> but other less common wetland types also deposit peat, including fens, pocosins, and peat swamp forests. Other words for lands dominated by peat include moors or muskegs. Landscapes covered in peat also have specific kinds of plants, particularly Sphagnum moss, ericaceous shrubs, and sedges (see bog for more information on this aspect of peat). Since organic matter accumulates over thousands of years, peat deposits also provide records of past vegetation and climates stored in plant remains, particularly pollen. Hence, they allow humans to reconstruct past environments and changes in human land use.<ref>Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. 323-325</ref>

Peat is harvested as an important source of fuel in certain parts of the world. By volume, about 4 trillion m³ of peat are in the world, covering a total of around 2% of global land area (about 3 million km²), containing about 8 billion terajoules of energy.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Over time, the formation of peat is often the first step in the geological formation of other fossil fuels such as coal, particularly low-grade coal such as lignite.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Depending on the agency, peat is not generally regarded as a renewable source of energy, as its extraction rate in industrialized countries far exceeds its slow regrowth rate of 1 mm per year,<ref name="Keddy, P.A 2010">Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Chapter 7.</ref> and as peat regrowth is also reported to take place in only 30-40% of peatlands.<ref>http://www.eurosaiwgea.org/Activitiesandmeetings/OtherEUROSAIWGEAmeetings/Documents/Estonia_energy.pdf</ref> Because of this, the United Nations Framework Convention on Climate Change (UNFCCC),<ref name="seai.ie">http://www.seai.ie/Archive1/Files_Misc/IEABioenergyAgreementTask38CaseStudy.pdf</ref> and another organization affiliated with the United Nations classifies peat as a fossil fuel.<ref>http://www.un-documents.net/ocf-07.htm Today's primary sources of energy are mainly non-renewable: natural gas, oil, coal, peat, and conventional nuclear power. There are also renewable sources, including wood, plants, dung, falling water, geothermal sources, solar, tidal, wind, and wave energy, as well as human and animal muscle-power. Nuclear reactors that produce their own fuel ("breeders"), and eventually fusion reactors, are also in this category.</ref> However, the Intergovernmental Panel on Climate Change has begun to classify peat as a "slow-renewable" fuel.<ref>http://www.worldenergy.org/publications/survey_of_energy_resources_2007/peat/704.asp</ref> This is also the classification used by many in the peat industry.<ref name="seai.ie"/>

At 106 g CO2/MJ,<ref name="imcg.net">The CO2 emission factor of peat fuel. Imcg.net. Retrieved on 2011-05-09.</ref> the carbon dioxide emission intensity of peat is higher than that of coal (at 94.6 g CO2/MJ) and natural gas (at 56.1).

Peat fires have been responsible for some large public health disasters, including the 1997 Southeast Asian haze.


Peat sections
Intro   Peatlands distribution   Formation  Types of peat material  Characteristics and uses  Environmental and ecological issues  Wise use and protection  See also   Notes   References  External links  

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