Satellite image of the island of Borneo on 19 August 2002, showing smoke from burning peat swamp forests
Peat swamp forests are tropical moist forests where waterlogged soil prevents dead leaves and wood from fully decomposing. Over time, this creates a thick layer of acidic peat. Large areas of these forests are being logged at high rates.
Peat swamp forests are typically surrounded by lowland rain forests on better-drained soils, and by brackish or salt-water mangrove forests near the coast.
Over the past decade[date missing], the government of Indonesia has drained some peat swamp forests of the island of Borneo for conversion to agricultural land. The dry years of 1997-8 and 2002-3 saw huge fires in the peat swamp forests. A study for the European Space Agency found that the peat swamp forests are a significant carbon sink for the planet, and that the fires of 1997-8 may have released up to 2.5 billion tonnes, and the 2002-3 fires between 200 million to 1 billion tonnes, of carbon into the atmosphere. Much of the emissions from peatlands in Borneo are due to changes in their hydrological regime, caused by drainage from nearby plantations (particularly oil palm). Peatland conservation and rehabilitation are more efficient undertakings than reducing deforestation (in terms of claiming carbon credits from REDD initiatives), due to the much larger reduced emissions achievable per unit area and the much lower opportunity costs involved. Indonesia contains 50% of tropical peat swamps and 10% in the world.