TY - JOUR
T1 - Discrepancies and Uncertainties in Bottom-up Gridded Inventories of Livestock Methane Emissions for the Contiguous United States
AU - Hristov, Alexander N.
AU - Harper, Michael
AU - Meinen, Robert
AU - Day, Rick
AU - Lopes, Juliana
AU - Ott, Troy
AU - Venkatesh, Aranya
AU - Randles, Cynthia A.
N1 - Funding Information:
This study was partially funded by ExxonMobil Research and Engineering Company. The authors thank David Lyon (Environmental Defense Fund) and Marc L. Fischer and Seongeun Jeong (Lawrence Berkeley National Laboratory) for providing methane emission data for the Barnett Shale region of Texas and CALGEM, respectively.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/12/5
Y1 - 2017/12/5
N2 - In this analysis we used a spatially explicit, simplified bottom-up approach, based on animal inventories, feed dry matter intake, and feed intake-based emission factors to estimate county-level enteric methane emissions for cattle and manure methane emissions for cattle, swine, and poultry for the contiguous United States. Overall, this analysis yielded total livestock methane emissions (8916 Gg/yr; lower and upper 95% confidence bounds of ±19.3%) for 2012 (last census of agriculture) that are comparable to the current USEPA estimates for 2012 and to estimates from the global gridded Emission Database for Global Atmospheric Research (EDGAR) inventory. However, the spatial distribution of emissions developed in this analysis differed significantly from that of EDGAR and a recent gridded inventory based on USEPA. Combined enteric and manure methane emissions from livestock in Texas and California (highest contributors to the national total) in this study were 36% lesser and 100% greater, respectively, than estimates by EDGAR. The spatial distribution of emissions in gridded inventories (e.g., EDGAR) likely strongly impacts the conclusions of top-down approaches that use them, especially in the source attribution of resulting (posterior) emissions, and hence conclusions from such studies should be interpreted with caution.
AB - In this analysis we used a spatially explicit, simplified bottom-up approach, based on animal inventories, feed dry matter intake, and feed intake-based emission factors to estimate county-level enteric methane emissions for cattle and manure methane emissions for cattle, swine, and poultry for the contiguous United States. Overall, this analysis yielded total livestock methane emissions (8916 Gg/yr; lower and upper 95% confidence bounds of ±19.3%) for 2012 (last census of agriculture) that are comparable to the current USEPA estimates for 2012 and to estimates from the global gridded Emission Database for Global Atmospheric Research (EDGAR) inventory. However, the spatial distribution of emissions developed in this analysis differed significantly from that of EDGAR and a recent gridded inventory based on USEPA. Combined enteric and manure methane emissions from livestock in Texas and California (highest contributors to the national total) in this study were 36% lesser and 100% greater, respectively, than estimates by EDGAR. The spatial distribution of emissions in gridded inventories (e.g., EDGAR) likely strongly impacts the conclusions of top-down approaches that use them, especially in the source attribution of resulting (posterior) emissions, and hence conclusions from such studies should be interpreted with caution.
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U2 - 10.1021/acs.est.7b03332
DO - 10.1021/acs.est.7b03332
M3 - Article
C2 - 29094590
AN - SCOPUS:85038211330
SN - 0013-936X
VL - 51
SP - 13668
EP - 13677
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 23
ER -