Greenhouse Gas Emissions from Canadian Peat Extraction, 1990–2000: A Life-cycle Analysis

Abstract

This study uses life-cycle analysis to examine the net greenhouse gas (GHG) emissions from the Canadian peat industry for the period 1990-2000. GHG exchange is estimated for land-use change, peat extraction and processing, transport to market, and the in situ decomposition of extracted peat. The estimates, based on an additive GHG accounting model, show that the peat extraction life cycle emitted 0.54 x 10(6) t of GHG in 1990, increasing to 0.89 x 10(6) t in 2000 (expressed as CO2 equivalents using a 100-y time horizon). Peat decomposition associated with end use was the largest source of GHGs, comprising 71% of total emissions during this 11-y period. Land use change resulted in a switch of the peatlands from a GHG sink to a source and contributed an additional 15%. Peat transportation was responsible for 10% of total GHG emissions, and extraction and processing contributed 4%. It would take approximately 2000 y to restore the carbon pool to its original size if peatland restoration is successful and the cutover peatland once again becomes a net carbon sink.

Substitution of peat moss with softwood biochar for soil-free marigold growth

“…Such a perception in part stems from the negative impacts on wetland ecosystems of some peat mining operations (Barkham, 1993;Robertson, 1993), though the sustainability of peat harvesting is a subject of debate (Chapman et al, 2003;Hood, 1999). Peat mining operations and the eventual decomposition of peat after its use in substrates represents a transformation of a terrestrial C sink of global importance into a net C source, with climate change forcing effects (Cleary et al, 2005;Gorham, 1991). Assuming a conservative aerobic decomposition rate for peat in substrates of 5% per annum (Cleary et al, 2005), within one century of mining and use in soil-free substrates 95% of mined peat would be expected to revert from a C sink to source (CO 2 ).…”

“…Peat mining operations and the eventual decomposition of peat after its use in substrates represents a transformation of a terrestrial C sink of global importance into a net C source, with climate change forcing effects (Cleary et al, 2005;Gorham, 1991). Assuming a conservative aerobic decomposition rate for peat in substrates of 5% per annum (Cleary et al, 2005), within one century of mining and use in soil-free substrates 95% of mined peat would be expected to revert from a C sink to source (CO 2 ). In contrast, high-temperature BCs are thought to generally exhibit lower decomposition rates than undecomposed or humified biomass such as compost and peat (Woolf et al, 2010) and exhibit centennial to millennial residence times (Gurwick et al, 2013).…”

“…The organic component provides high porosity, low bulk density, and nutrient retention (e.g., water, nutrient ions) (Raviv et al, 1986), which makes Sphagnum peat moss a strongly suitable option with widespread use (Carlile et al, 2015;Robinson and Lamb, 1975). However, increasing expense and competing uses for peat (Caron et al, 2015), impacts of its harvest on wetland ecosystems (Barkham, 1993;Robertson, 1993), including loss of peat bogs as a key global C sink (Cleary et al, 2005), and its perception as unsustainable (Caron et al, 2015) have spurred recent investigations of substitutes for peat in soil-free substrates, including biomass waste products such as compost and sawdust (e.g., Ceglie et al, 2015;Maas and Adamson, 1972;Wright et al, 2009;Álvarez et al, 2017).…”

Moisture dynamics and hydrophysical properties of a transplanted acrotelm on a cutover peatland

“…Within North America, approximately two-thirds of the peat extraction for horticultural purposes occurs within Canada and the demand for horticultural peat over the past century has lead to the drainage and extraction of over 12 000 ha of peatlands (Cleary et al, 2005). In areas such as the St Lawrence lowlands in Québec, loss of peatlands for peat extraction exceed 70% (Van Seters and Price, 2001).…”

Experimental drying intensifies burning and carbon losses in a northern peatland

“…However, changes in either longterm carbon uptake or losses resulting from changes in climate or land use could alter the function of peatlands within the climate system. Across the boreal region, peatland hydrology is affected by numerous land uses, including drainage for agriculture, forestry, peat harvesting, and oil and gas extraction [10][11][12][13] . Agriculture and forestry are considered the primary land uses affecting peatlands globally.…”