Peat covers 3 percent of land but holds more carbon than all forests
Peatlands blanket only about 3 percent of Earth's land, yet they store up to 550 gigatonnes of carbon, some 42 percent of all soil carbon and more than every other vegetation type combined, forests included. That stockpile grew about a millimetre a year for thousands of years, and draining or burning it sends the carbon back skyward.
Peat is plant matter that never finished rotting. In waterlogged bogs, fens and swamp forests, stagnant water keeps oxygen out and slows decay, so dead vegetation piles up. Sphagnum moss is a master of this. It secretes tannins that preserve organic material and has special water-holding cells that keep the bog constantly wet, reshaping its surroundings to favour more peat, a process called habitat manipulation.
Most modern bogs formed at high latitudes about 12,000 years ago, after the glaciers of the last ice age retreated. Boreal peatlands average 1.5 to 2.3 metres deep and hold around 415 gigatonnes of carbon, about 46 times global carbon dioxide emissions in 2019. Because layers build up so slowly, peat preserves pollen and plant remains, letting scientists reconstruct past climates and land use. Over geological time, peat is often the first stage in forming coal, especially lignite.
The biggest peatlands include the West Siberian Lowland, Canada's Hudson Bay Lowlands and the Mackenzie River Valley. The largest tropical peatland lies in the Democratic Republic of Congo, and South America's biggest complex sits in the Peruvian Amazon near Iquitos. Indonesia has more tropical peatland than any other country but is losing wetlands at about 100,000 hectares a year. A recent global map, PEATMAP, puts total coverage at 4.23 million square kilometres, and peat makes up about 60 percent of the world's wetlands.
In theory peat is renewable, but extraction in industrial countries far outpaces regrowth of roughly a millimetre a year, and regrowth happens in only 30 to 40 percent of peatlands. Gardeners' use of it is being banned in some places. Engineers dislike it for another reason: peat soils compact poorly, making them unstable foundations for roads and buildings.
Source: Peat
