24 Aug 2020

24 Aug 2020

Review status: a revised version of this preprint was accepted for the journal ESSD and is expected to appear here in due course.

Facility scale inventory of dairy methane emissions in California: Implications for mitigation

Alison R. Marklein1, Deanne Meyer2, Marc L. Fischer3, Seongeun Jeong3, Talha Rafiq1, Michelle Carr1, and Francesca M. Hopkins1 Alison R. Marklein et al.
  • 1University of California Riverside, Department of Environmental Science, Riverside, CA 94611, USA
  • 2University of California Davis, Department of Animal Science, One Shields Avenue, Davis, CA 95616, USA
  • 3Lawrence Berkeley National Laboratory, Energy Technologies Area, Cyclotron Road, Berkeley, CA 94720, USA

Abstract. Dairies emit roughly half of total methane (CH4) emissions in California, generating CH4 from both enteric fermentation by ruminant gut microbes and anaerobic decomposition of manure. Representation of these emission processes is essential for management and mitigation of CH4 emissions, and is typically done using standardized emission factors applied at large spatial scales (e.g., state level). However, CH4-emitting activities and management decisions vary across facilities, and current inventories do not have sufficiently high spatial resolution to capture changes at this scale. Here, we develop a spatially-explicit database of dairies in California, with information from operating permits and California-specific reports detailing herd demographics and manure management at the facility scale. We calculated manure management and enteric fermentation CH4 emissions using two previously published bottom-up approaches and a new farm-specific calculation developed in this work. We also estimate the effect of mitigation strategies – the use of mechanical separators and installation of anaerobic digesters – on CH4 emissions. We predict that implementation of digesters at the 109 dairies that are existing or planned in California will reduce manure CH4 emissions from those facilities by an average of 35 %, and total state CH4 emissions by 6 % (or ~ 47.3 Gg CH4/yr). In addition to serving as a planning tool for mitigation, this database is useful as a prior for atmospheric observation-based emissions estimates, attribution of emissions to a specific facility, and to validate CH4 emissions reductions from management changes. Raster files of the datasets and associated metadata are available from the Oak Ridge National Laboratory Distributed Active Archive Center for Biogeochemical Dynamics (ORNL DAAC; Marklein et al., 2020;

Alison R. Marklein et al.

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Alison R. Marklein et al.

Data sets

Dairy Sources of Methane Emissions in California Alison R. Marklein, Deanne Meyer, Marc L. Fischer, Seongeun Jeong, Talha Rafiq, Michelle Carr, and Francesca M. Hopkins

Alison R. Marklein et al.


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Short summary
Dairy cow farms produce half of California's (CA) methane (CH4) emissions. Current CH4 emission inventories lack regional variation in management and are inadequate to assess CH4 mitigation measures. We develop a spatial database of CH4 emissions for CA dairy farms including farm-scale herd demographics and management data. This database is useful to predict CH4 emission reductions from mitigation efforts, to compare with atmospheric CH4 observations and to attribute emissions to specific farms.