How Peatlands Capture Carbon
Edward Struzik: Peatlands represent just 3 percent of the world’s terrestrial surface, but store twice as much carbon as all the world’s forests combined. Canada’s Hudson Bay Lowlands, the largest intact peatland in the world, stores as much as five times more carbon than the equivalent area in the Amazon rainforest.
Miriam Jones: Plants growing at the peat’s surface take up carbon dioxide from the atmosphere. In most other ecosystems, when plants die, they decompose, returning that carbon to the atmosphere. In peatlands, however, the water at or close to the surface limits oxygen. Without oxygen, decomposition is slow. Much of this plant matter only partially decomposes, then accumulates in layers, turning into peat. Peat sequesters carbon because the decomposition is slower than the accumulation, and over time peat can accumulate to be several meters thick.
Gusti Anshari: Major factors that directly affect the degradation of tropical peats are land use and peat fires. The Intergovernmental Panel on Climate Change forecasts that the tropical peat ecosystem could become a large contributor to atmospheric carbon dioxide.
Jones: Destroying the world’s peatlands could double the amount of carbon in the atmosphere. Peatlands have accumulated this carbon since the last ice age, about 20,000 years ago, but mostly in the last 11,500 years or so. Globally, damaged peatlands are net carbon sources — that is, they release carbon into the atmosphere — through disturbances like drainage or fires, or the drying of the peat surface and thawing of permafrost due to climate change. Some peatlands, however, especially in the northern high latitudes, remain net carbon sinks.
Struzik: When frozen peatlands in the Arctic and sub-Arctic begin to thaw, they reach a point where they can no longer absorb and store carbon, and start emitting it instead. This is already happening. Wildfires and climate change are accelerating this thawing. In 2007, the largest recorded tundra fire to occur in the Arctic, which burned 401 square miles, released as much carbon into the atmosphere as the tundra has stored in the previous 50 years.