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Climate mitigation by dairy intensification depends on intensive use of spared grassland

Author:
Styles, David, Gonzalez‐Mejia, Alejandra, Moorby, Jon, Foskolos, Andreas, Gibbons, James
Source:
Global change biology 2018 v.24 no.2 pp. 681-693
ISSN:
1354-1013
Subject:
afforestation, attributional life cycle assessment, beef, beef cattle, carbon, carbon footprint, cattle feeds, climate, consequential life cycle assessment, corn, cows, crop production, dairy farming, developed countries, feed conversion, grasslands, grazing intensity, greenhouse gas emissions, greenhouse gases, inventories, land use change, meat production, milk, milk yield, pollution control, Brazil, United Kingdom
Abstract:
Milk and beef production cause 9% of global greenhouse gas (GHG) emissions. Previous life cycle assessment (LCA) studies have shown that dairy intensification reduces the carbon footprint of milk by increasing animal productivity and feed conversion efficiency. None of these studies simultaneously evaluated indirect GHG effects incurred via teleconnections with expansion of feed crop production and replacement suckler‐beef production. We applied consequential LCA to incorporate these effects into GHG mitigation calculations for intensification scenarios among grazing‐based dairy farms in an industrialized country (UK), in which milk production shifts from average to intensive farm typologies, involving higher milk yields per cow and more maize and concentrate feed in cattle diets. Attributional LCA indicated a reduction of up to 0.10 kg CO₂e kg⁻¹ milk following intensification, reflecting improved feed conversion efficiency. However, consequential LCA indicated that land use change associated with increased demand for maize and concentrate feed, plus additional suckler‐beef production to replace reduced dairy‐beef output, significantly increased GHG emissions following intensification. International displacement of replacement suckler‐beef production to the “global beef frontier” in Brazil resulted in small GHG savings for the UK GHG inventory, but contributed to a net increase in international GHG emissions equivalent to 0.63 kg CO₂e kg⁻¹ milk. Use of spared dairy grassland for intensive beef production can lead to net GHG mitigation by replacing extensive beef production, enabling afforestation on larger areas of lower quality grassland, or by avoiding expansion of international (Brazilian) beef production. We recommend that LCA boundaries are expanded when evaluating livestock intensification pathways, to avoid potentially misleading conclusions being drawn from “snapshot” carbon footprints. We conclude that dairy intensification in industrialized countries can lead to significant international carbon leakage, and only achieves GHG mitigation when spared dairy grassland is used to intensify beef production, freeing up larger areas for afforestation.
Agid:
5890562