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Questioning the Accuracy of Greenhouse Gas Accounting from Agricultural Waste: A Case Study
Author(s) -
Chung Matthew L.,
Shilton Andrew N.,
Guieysse Benoit,
Pratt Chris
Publication year - 2013
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0350
Subject(s) - greenhouse gas , environmental science , agriculture , waste management , environmental engineering , engineering , geography , geology , archaeology , oceanography
The New Zealand Greenhouse Gas Inventory (the NZ Inventory) uses country‐specific data to quantify CH 4 emissions from anaerobic ponds treating dairy farm effluent (315 Gg CO 2 equivalent [CO 2 –e] in 2009). In this study, we used literature data to: (i) evaluate the accuracy of the NZ Inventory's parameters used to quantify these CH 4 emissions; and (ii) determine whether the NZ Inventory's scope is capturing the full spectrum of sources with bio‐CH 4 potential entering anaerobic ponds. The research indicated that the current NZ Inventory methodology is underestimating CH 4 emissions from anaerobic ponds across New Zealand by 264 to 603 Gg CO 2 –e annually. Moreover, the NZ Inventory is currently not accounting for (i) manure from supplementary feed pads and stand‐off pads (annual CH 4 emissions = 207–330 Gg CO 2 –e); (ii) waste milk (153–280 Gg CO 2 –e); and (iii) supplementary feed waste (90–216 Gg CO 2 –e). Annual CH 4 emissions from anaerobic ponds on dairy farms across New Zealand are thus more likely to be 1029 to 1744 Gg CO 2 –e, indicating that the NZ Inventory is reporting as little as 18% of actual CH 4 emissions produced by this sector. These additional wastes are not accounted for in the methodology prescribed by the Intergovernmental Panel on Climate Change for estimating CH 4 emissions from dairy manure. Consequently, other significant dairying nations will also probably be underestimating their waste CH 4 emissions. Our research highlights that, if governments attempt to include country‐specific emission factors in their greenhouse gas inventories, these factors must be based on an assessment of the full spectrum of sources contributing to greenhouse gas emissions within any given sector.