Global Perspectives on Peat Fires

The global peat carbon pool exceeds that of global vegetation and is similar to the current atmospheric carbon pool. Because fire is increasingly appreciated as a threat to peatlands and their carbon stocks, here we discuss controls on and effects of peat fires across biomes and how they vary. Peat fires are dominated by smoldering combustion, which is easier to ignite and persists under greater moisture content than flaming combustion. In undisturbed peatlands, the peat C stock typically is protected from deep smoldering, and fire resistance has played a role in tropical and boreal peat carbon storage over millennia. However, drying mediated by climate change and anthropogenic activity is altering peatland hydrology and increasing the frequency and extent of peat fires; in some cases, processes of drying and fire may be coupled in positive feedbacks that could result in increasingly large fires and consequent releases of carbon to the atmosphere. The combustion of deep peat affects older soil carbon that has not been part of the active carbon cycle for centuries to millennia, and will dictate the importance of peat fire emissions with respect to future climate change and human health effects.