Linking environmental and economic modelling for informing policymaking in agriculture

The European Green Deal recognises the importance of addressing the environmental challenges posed by agriculture to meet the global biodiversity and climate agendas. Environmental policymaking is needed to drive and speed up sustainability transitions in agriculture because the environmental consequences of agricultural activities are not generally reflected in production costs and lead to market-driven production systems that are not delivering optimal outcomes for society. This thesis contributes scientific analysis for informing policymaking on the benefits and trade-offs of environmental measures concerning arable-land management, bioenergy crops with local soil co-benefits, a price on greenhouse gas emissions, and the removal of coupled income support to cattle.Chapters 1 and 2 study the societal benefits of improving arable-land management across the EU. This is done with a systematic review and meta-analysis of time series data in long-term field experiments, reported statistics on farm management and economic valuation of C sequestration for climate-change mitigation. Results from chapter 1 show that combining crop rotations, reduced tillage, organic amendments and soil cover can effectively restore soil organic carbon stocks in intensive arable land in climatic regions where wheat can grow. Chapter 2 shows substantial variation in climate-change mitigation benefits from soil management improvements across the EU. This indicates substantial potential to enhance cost-effectiveness of a payment eco-scheme promoting C sequestration through soil management by basing payment levels on expected benefits rather than adoption costs.Chapters 3 and 4 analyse the environmental implications of policy interventions that advance (at least some) aspects of the European Green Deal for agriculture, namely a subsidy to promote arable grass for bioenergy, a price on greenhouse gas emissions, and removal of the Coupled Income Support to cattle. Both regional and global environmental aspects are captured by linking agent-based modelling of farming regions and territorial Life Cycle Assessment. The environmental implications of policy interventions are strongly influenced by regional structure features, and in particular changes in relative productivity, which can vary widely between intensive and extensive farming regions in the EU. This confirms the importance of adapting environmental policymaking to regional conditions and supports the regional development of the 2023 reform of the Common Agricultural Policy, which also enhances national governance of the payment structure. Agent-based Life Cycle Assessment has thus the potential to speed up sustainability transitions in agriculture by contributing to identify the need or redundance of complementary policy interventions prior to implementation.