Peatlands occur in every climatic zone and, according to Page et al. (2011), the total area globally is around 4 million km2 making them 70% of natural freshwater wetland or 3% of the Earth’s land surface. The distribution of peatlands globally follows that of wetlands generally.
The largest known concentrations of peatland are found in Canada and Alaska, Northern Europe and Western Siberia, Southeast Asia, and parts of the Amazon basin, where more than 10% of the land area is covered with peatlands. (Joosten & Clarke, 2002, Wise Use of Mires and Peatlands).
The majority of the world’s peatlands occur in boreal and temperate parts of the Northern Hemisphere, especially, Europe, North America and Russia where they have formed under high precipitation-low temperature climatic regimes.
In the humid tropics, however, regional environmental and topographic conditions enable peat to form under conditions of high precipitation and high temperature (Andriesse, 1988; Page et al., 1999) in Southeast Asia, mainland East Asia, the Caribbean, Central America, South America, Africa, parts of Australasia and a few Pacific Islands (Page et al., 2011).
Most tropical peatlands are located at low altitudes where rain forest vegetation grows on a thick layer of organic matter although some are found in upland or mountainous areas where peat can exceed 30 m (Bord na Mona, 1985; Pajunen, 1985).
Map @ Lappalainen, Global Peat Resources, IPS 1996