The utility of novel environmental impact metrics in UK ruminant mitigation

Much of the UK land sector’s environmental impact comes from the production of beef and dairy. Conventional metrics, which understate both the impact of methane reductions and the carbon opportunity cost of land, attribute most of this impact to enteric methane and land-use change from imported soy for feed. Recent developments in agricultural impact metrics necessitate investigation into whether continued reliance on conventional metrics could undermine national (and global) progress on climate and deforestation targets. This article estimates emissions and land use impacts associated with cattle in the UK and applies various combinations of metrics under four futures simulating a range of technological and policy levers. We find that the use of alternative metrics can highlight the potential impact of interventions that might have been overlooked when using conventional metrics, particularly encouraging more efficient production by including the carbon cost of foregone sequestration. We suggest that a range of metrics should be considered to ensure mitigation strategies which deliver on global outcomes, and show that estimates of absolute sectoral impact are acutely sensitive to methodological choices in how it is measured. We also find that the rank-ordering of different intervention strategies for the UK is largely insensitive to metric choice, though this may not be the case for all agricultural systems.