Exploring net zero greenhouse gas emission strategies for the Irish agriculture and land use sectors

Ireland has set ambitious net zero greenhouse gas (GHG) emission targets across all sectors by 2050. Lowering national climate impact alongside other environmental targets for biodiversity, air and water quality and producing green energy, while producing food for a growing global population, will require tremendous effort and a transformation of the Agriculture, Forestry and Other Land Use (AFOLU) sector. Since 2010, the gap has widened between annual GHG emissions and climate targets of the agricultural sector and sustainable developments across various environmental quality indicators prior to the removal of EU milk quotas were reversed.

Integrated assessment modelling is pertinent to investigate dynamics between agriculture and land use to define strategies and synergies for a multi-beneficial land sector that contributes to various environmental targets. Previous studies have unveiled that net zero GHG emission scenarios entail a substantial transformation of current herd dynamics, production systems and change in land use. Therefore, this research presents novel livestock and grassland models that improve the precision of modelling pasture-based livestock systems and the areas they occupy under different production systems by relating emission factors to individual feed and grass requirements. Based on these models, the integration of a white clover system using data collected from 39 farms across Ireland and six other aspects contributing GHG emission reduction from the AFOLU sector, national net zero emission scenarios were developed with the aim of maintaining bovine protein production.

Results indicate that a transformation of the current livestock herd configuration, alongside vast improvements of productivity and mitigation measures are required to meet 2050 net zero targets. This entailed the sparing of at least 1.5 million ha of grassland currently under agriculture for the generation of carbon dioxide removal from the land use sector, for example through afforestation and rewetting of organic soils. The white clover system was found to be an important measure that reduces agricultural emissions through the displacement of inorganic nitrogen fertiliser while sparing land due to larger dry matter yields than in present systems. In addition, the thesis evaluates a variety of net zero definitions within GWP100 accounting and their impact on successful scenarios.

To conclude, this thesis demonstrates pathways towards meeting net zero GHG emissions in Ireland for the AFOLU sector by 2050 while maintaining current levels of bovine protein production. These results will be a major asset to support public discussion, policy and academic stakeholders by outlining options and choices that can be made for a sustainable future of Irish agricultural and the magnitude of change from current production systems that is required.