Sphagnum, the peatland carbon economy, and climate change

Northern peatlands cover about 3% of the Earth's land surface and contain about 600 Gt of carbon — about the same amount as there is in CO₂ in the atmosphere. Species of Sphagnum are abundant in most of these peatlands and are amongst the most important fixers of carbon. In the context of concerns about atmospheric CO₂ concentrations and climate change, peatlands as carbon sinks were a 'Good Thing' in the sense implied by R. J. Sellars & W. C. Yeatman. The key idea here is that the catotelm is the true peat accumulating layer; the living plants in the acrotelm, among which Sphagnum is usually conspicuous, fix carbon and decay predominantly aerobically but at different rates. The sideways arrow represents losses as soluble carbon in runoff through the acrotelm. The two main carbon-containing gases that exchange with the peatland surface is CO₂ and CH₄.