Peat, the accumulated turf made up of decayed vegetation, forms in many parts of the world in places like bogs, moors, and swamp forests. Due to its high carbon content, it can be harvested and burned as fuel. There are estimates that the global inventory of peat, covering 2 percent of all land area, contains 8 billion terajoules of energy. A new study has revealed that peat also has a high potential to contribute to climate change. The study, published by researchers from Bangor University in Maine, found that drought causes the release of far more carbon dioxide from peat than previously assumed.
Peatlands are areas of land with a naturally accumulated layer of peat. Peatlands are found in at least 175 countries and cover around 4 million km2 or 3% of the world’s land area. In Europe, peatlands extend to ca. 515,000 km2.
Peat forms when plant material, usually in marshy areas, is inhibited from decaying fully by acidic and anaerobic conditions. It is composed mainly of marshland vegetation: trees, grasses, fungi, as well as other types of organic remains, such as insects, and animal remains. Under certain conditions, the decomposition of the latter (in the absence of oxygen) is inhibited, and archaeologists often take advantage of this.
Peat layer growth and the degree of decomposition (or humification, transformation to humus) depends principally on its composition and on the degree of waterlogging. Peat formed in very wet conditions accumulates considerably faster, and is less decomposed, than that in drier places. This allows climatologists to use peat as an indicator of climatic change. The composition of peat can also be used to reconstruct ancient ecologies by examining the types and quantities of its organic constituents.
Under the proper conditions, peat is the earliest stage in the formation of coal.
Most modern peat bogs formed in high latitudes after the retreat of the glaciers at the end of the last ice age some 9,000 years ago. They usually grow slowly, at the rate of about a millimetre per year.
The peat in the world’s peatlands has been forming for 360 million years and contains 550 Gt of carbon.
Peat deposits are found in many places around the world, notably in Ireland, Russia, Belarus, Ukraine, Finland, Lithuania, Latvia, Estonia, Scotland, Northern England (Particularly in the Pennines), Wales, Poland, northern Germany, the Netherlands, Denmark, Norway, Sweden, New Zealand and in North America, principally in Canada and the United States (Michigan, Minnesota, the Florida Everglades, and California’s Sacramento-San Joaquin River Delta). The amount of peat is smaller in the southern hemisphere, partly because there is less land, but peat can be found in New Zealand, Kerguelen, Southern Patagonia/Tierra del Fuego and the Falkland Islands, Indonesia (Kalimantan (Sungai Putri, Danau Siawan, Sungai Tolak, Rasau Jaya (West Kalimantan), and Sumatra). Indonesia has more tropical peat land and mangrove forests than any other nation on earth, but Indonesia is losing wetlands by 100,000 hectares per year.
Approximately 60% of the world’s wetlands are peat. About 7% of total peatlands have been exploited for agriculture and forestry.[citation needed] Under proper conditions, peat will turn into lignite coal over geologic periods of time.
Peatlands of the world lie in regions which are predicted to experience more frequent and severe droughts as climate change deepens. This will lead to the peat drying out and releasing vast quantities of CO2 into the atmosphere. Peat normally contains ample moisture which locks in the greenhouse gas. As it dries, the peat becomes exposed to the air where CO2 can be released.
The new study was published in the journal Nature Geosciences by Dr. Nathalie Fenner and Professor Chris Freeman of Bangor University. They found that not only with drought increase the rate of CO2 release, but that the release will also continue after the drought has concluded and the peat is re-wetted. This is because the new rainwater will drain away the dried out peatlands as dissolved organic carbon, where it can also be released.
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