WP5: Re-Assessment of livestock farm systems | Update

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In a new report three crucial methodological choices when applying life cycle assessments (LCA) in livestock systems were investigated and discussed. Recommendations for how to handle these issues in the Re-livestock project and more generally were given.

Functional units should be selected reflecting the goal and scope of the study considering carefully the different functions a livestock system provides including both provisioning (e.g. meat) and non[1]provisioning ecosystem services (e.g. habitat creation and maintenance). When accounting for biogenic carbon in LCA of agricultural systems, both changes in soil organic carbon (SOC) as well as in woody biomass can be relevant.

The choice of reference situation is crucial and strongly influences results. In general, carbon stored in soils or biomass should be reported separately from fossil carbon and results need to be interpreted with caution. In addition, an uncertainty or sensitivity analysis should, to the extent possible, be performed on SOC changes. To calculate the carbon footprint of a product, established metrics such as global warming potential (GWP) and global temperature potential (GTP) are recommended.

Using the new metric GWP* for climate footprints is discouraged for two reasons: (1) method details around baselines have proven difficult and confusing for many people; and (2) GWP* has no advantage in principle over a time-dependent application of GTP, which is a more established and widely understood metric.

Using a dynamic approach, such as GWP* or other simple climate models, can be useful to highlight potential trade-offs between short-term and long term warming effects. In a dynamic approach, climate impact is however not reduced to one number, but rather a time series of numbers indicating the climate impact, e.g., as global temperature change (GTP) or CO2 warming-equivalents (GWP*).

Click here to read the full report.