Peat wildfires

Dry peat ignites very easily and can burn for days or weeks, even smouldering underground and re-emerging away from the initial source (Fig. 1 & 2). This makes these fires incredibly difficult to extinguish, and highly unpredictable and uncontrollable.

Forest fire in Boreno

Fig. 1: Peat swamp fire in Borneo. Image credit: http://www.outrop.com/

Some of the most severe peat fire events from 1960 to the present day have occurred during years of low rainfall induced by El Niño–Southern Oscillation (ENSO). The fires of 1997-98 burned 9.7–11.7 million ha on Borneo and Sumatra, destroying 4.5–6 million ha of species rich Dipterocarp forest (including 1.5–2.1 million on peat soils). Estimated carbon emissions from these 1997-98 fires on peatlands were 0.81–2.57 Pg, equivalent to 13–40% of annual global fossil fuel emissions. Peatland fires are promoted by deforestation and forest degradation, which is ultimately linked to peatland drainage. Fires are extremely rare in non-degraded and non-drained peatlands; but in drained peatlands, fires can last for weeks, sometimes even months, burning downwards into the thick layers of peat over large areas. The peat fires in South-east Asia can burn millions of hectares in one dry season. For 2015, emissions from peat fire and decomposition were comparable in magnitude, with estimated fire emissions ~0.43 Pg and ~0.44 Pg from oxidation. If the current emissions are combined for SE Asian peatlands they equate to almost 8% of global emissions from fossil fuel burning. This is probably the most concentrated (produced on only 0.2% of the global land area) land-use related CO2 emission in the world. These emissions have strongly increased since 1990 (+25%). Some of the most destructive peat fires occurred in 1997, 1998, 2002, 2013, 2014, and, very recently, in 2015. In each of these years over 1.5 to 2.2 million hectares of peatland burned in Sumatra and Kalimantan. The emissions in each year were estimated to have reached between 3.0 to 9.4 Pg CO2, or up to 40% of the global CO2 emissions. It is, however, important to note that ENSO conditions are not necessary anymore for peat fires in SE Asia to occur and to be sustained: drainage, sufficient peat dryness and a source of ignition, in most cases related to human activities, is sufficient to cause and sustain a peat fire.

Fire fighting

Fig. 2: Fire fighting in in Borneo. Image credit: http://www.outrop.com/

Peat fires diminish the natural resource base of local economies and cultures, and cause losses of property, natural assets, and business / livelihoods. Peat fires also cause serious health problems through atmospheric pollution (Fig. 3). During the peat fires of 1997-98, annual mean particulate matter concentrations reached 200 μg m-3 near fire sources for more than 50 days across Southeast Asia (Southeast Sumatra and Southern Borneo), which exceeds the World Health Organization's 24-hr air quality target (50 μg m-3). It has been estimated that ~30% of all children living in  the locality of peatlands in Indonesia have respiratory diseases and growth inhibition as a result of peat haze / smoke. Indonesian peatland fires, for example, have been the cause of thousands of hospitalizations, and the rapid reduction in biodiversity and a range of other ecosystem services.

Smoke covers Palangkaraya, Central Kalimantan, Indonesian Borneo

Fig. 3: Smoke covers Palangkaraya, Central Kalimantan, Indonesian Borneo. Image credit: Suzanne Turnock and OuTrop

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