Greenhouse gas emission computing methods analysed

Whether climate change policy makers will eventually use IPCC or LCA to compute greenhouse gas (GHG) emissions will have major implications for Irish farmers.

The Intergovernmental Panel on Climate Change (IPCC) method considers emissions from national sources and is used to evaluate compliance with emission targets. The Life cycle assessment (LCA) approach quantifies all emissions associated with, for example, dairy production, up to the point milk is sold from the farm, including embodied emissions (such as fertiliser manufacture).

Both methods were applied by Teagasc experts at Moorepark to evaluate the carbon footprint of grass-based and confinement dairy farming systems. The carbon footprint of the confinement system was 8% lower than the grazing system, using the IPCC.

Using the LCA method, however, the carbon footprint of the confinement system was 16% greater, compared with the grazing system.

This difference arose because the IPCC method only considers the components of dairy systems emissions that occur within national boundaries.

To avoid adopting dairy systems that reduce Irish emissions but increase global emissions, the present policy method (IPCC) needs to be changed to the more appropriate LCA method.