Press release 16.03.2006
Effects of peatland utilization on climate change were studied in a research project coordinated by Metla. The use of fuel peat currently causes a greenhouse effect of similar magnitude to that of coal when the whole life cycle is considered. This can be reduced by directing peat production to peatlands in agricultural use. As for post-production use, afforestation is a slightly better alternative than restoration of mires. The greenhouse effect of peat combustion can be clearly reduced through careful collection of residual peat, new peat harvesting methods, and by improving combustion techniques.
More than half of the mires in Finland, originally almost 10 million hectares in area, have been drained for forestry use and less than a million hectares for agricultural use. Only approximately 40% of original mire areas are in their natural state. The greater part of the area used for fuel peat production is drained peatland forests.
The UN Framework Convention on Climate Change (UN FCCC) requires countries to make greenhouse gas inventories and report on their emissions. The research results form a basis for reporting on greenhouse gases and provide tools for calculating a life cycle analysis of the use of fuel peat.
Mires bind carbon as biomass and release it as greenhouse gases
The carbon balance of pristine mires is sensitive to changes in climatic factors. The annual greenhouse gas balance of fens can vary between a net loss of over 1000 kg per hectare and a net gain of almost the same magnitude. Methane emissions from fens vary between 10 and 400 kg per hectare expressed in carbon, while for peat bogs maximum emissions amount to 150 kg.
Forestry is the most significant form of land use on mires. Earlier research results indicated that drained peatland forest soil was a significant carbon sink, but the new calculations suggest the opposite. According to model simulations, the carbon balance of drained peatland soils is negative, although carbon bound to tree biomass can still compensate for most soil emissions.
Afforestation of peatlands in agriculture and cut-away peatlands reduces the greenhouse effect. Afforestation slows down carbon emissions for a few decades when tree stand biomass increases. Concurrently, however, afforested cut-away and agricultural sites release nitrous oxide that enhances global warming even more efficiently than carbon dioxide and methane.
Restoration of cut-away peatlands creates long-term sinks for carbon dioxide, but methane emissions are ´gradually re-initiated during the mire development. Net binding of carbon on the restoration areas is initiated within a few years, when the water surface is kept at the surface peat level. Consequently, methane emissions follow with a delay when new organic matter is produced; the restoration area accumulating plant biomass can rapidly produce an exceptionally large annual methane emission.
The research programme ”Greenhouse impact of the use of peat and peatlands in Finland”, first coordinated by the University of Helsinki and later by Metla, was completed at the end of last year. It was funded by the Ministry of Agriculture and Forestry, the Ministry of Trade and Industry and the Ministry of the Environment. The research was conducted in close collaboration with the Metla research project Pools and fluxes of carbon in Finnish forests and their socio-economic implications (HMS).