The research team, led by Daniel Henn of the University of Galway together with colleagues at Munster Technological University and the Norwegian Institute of Bioeconomy Research, built twelve integrated scenarios for Ireland’s agriculture, forestry and other land use (AFOLU) sector out to 2050. They combined the GOBLIN land balance model, the LCAD 2.0 anaerobic digestion model, national bioresource databases and FAOSTAT trade data, then evaluated every scenario against twelve key performance indicators spanning production, land use, environmental impact and economic resilience. The approach deliberately couples two dimensions that previous studies had treated in isolation: national net zero pathways and farm-to-national-scale circularity strategies.

Four contrasting futures formed the backbone of the analysis. A Business as Usual (BAU) pathway extends the current trajectory, with gradual conversion of beef farms to dairy and moderate uptake of technical mitigation measures. Dairy Specialisation (DS) pursues climate neutrality through intensive, export-oriented dairy production paired with aggressive afforestation. Food Self-Sufficiency (FSS) imagines a world of disrupted trade in which Ireland must feed its own population with minimal imports. Diversification (DIV) reduces reliance on cattle, expands plant-based protein production from legumes and horticulture, and maintains export revenue across a broader portfolio. Each pathway was then modelled at three levels of circularity: Minimum, Energy-focused and Feed-focused.

The two circularity strategies differ fundamentally in what they close. Energy-focused circularity maximises the use of domestic crops, by-products and wastes (CBPW) as feedstock for anaerobic digestion, generating biomethane for grid injection, electricity and heat, while recycling nutrients back to land as digestate. Feed-focused circularity instead redirects by-product streams into the livestock feed system, displacing imported soya bean cake and other protein-rich concentrates. Ireland currently imports around 4.2 million tonnes of livestock feed annually, worth roughly one billion euros, alongside fertiliser inputs of about 560 million euros per year, so both strategies target significant exposure to global markets.

The headline finding is a matter of magnitude and hierarchy. The choice of net zero pathway itself dwarfed the effect of circularity on sustainability indicators. All three net zero pathways reduced utilised agricultural area by 28 to 55 percent relative to BAU, driven mainly by livestock reductions, and cut territorial agricultural emissions by 29 to 62 percent before land use sinks balanced the remainder to zero. Inorganic nitrogen fertiliser use, acidification and eutrophication potentials fell by 23 to 68 percent, showing genuine synergies between climate abatement and air and water quality. By comparison, circularity strategies shifted territorial agricultural emissions by only about eight percent in either direction.

But circularity proved decisive for resilience. Energy-focused scenarios increased bioenergy production by 352 to 658 percent relative to minimum circularity, drawing on roughly seven million tonnes of available CBPW, livestock manure and grass-clover feedstocks in the BAU and DS pathways. Digestate from anaerobic digestion replaced 11 to 16 percent of territorial inorganic nitrogen fertiliser inputs under energy-focused strategies. Feed-focused scenarios reduced overseas land demand and greenhouse gas emissions across all pathways by cutting imports, and both strategies together reduced combined domestic and overseas emissions by two to four percent relative to minimum circularity in most pathways.

The economic sensitivity analyses delivered perhaps the most striking results. When the researchers simulated market shocks that raised fertiliser, energy and feed import prices by up to 200 percent, trade balances under minimum circularity scenarios turned negative, while energy- and feed-focused circularity strategies maintained positive balances across all non-BAU pathways. Avoided energy imports from domestic bioenergy production alone were valued at up to three to five billion euros. The team also tested carbon pricing: at 250 euros per tonne of carbon dioxide equivalent, BAU compliance costs of 5.7 to 6.8 billion euros would erase 72 to 88 percent of net export value, while at 500 euros the sector would face annual losses of 3.2 to 5.8 billion euros. Circularity, in short, functions as insurance against a turbulent world.

The study also surfaced unanticipated trade-offs. Energy-focused circularity sometimes diverted human-edible by-products from livestock feed into digesters, increasing import demand and raising overseas emissions by up to 16 percent, while digestate handling increased eutrophication potential. Feed-focused circularity boosted net human-edible protein production in BAU and DS scenarios but halved it in the Diversification pathway, where beans grown for direct human consumption were partly displaced by soya processed into animal feed. Fibre-rich by-products such as cereal straw proved counterproductive in feed, raising enteric methane emissions, and soil incorporation remained their best use. These nuances matter because territorial climate targets may favour energy-focused measures while agri-food companies tracking product carbon footprints may favour feed-focused ones, a potential policy misalignment the authors flag explicitly.

Carbon leakage, a persistent criticism of livestock reduction in exporting countries, appears limited in most scenarios because protein output remains broadly stable, with dairy exports compensating for reduced beef in the DS pathway. The exception is Food Self-Sufficiency, where trade barriers make production shifts elsewhere inevitable, though the direction of any leakage depends on the global socioeconomic context and cannot be assumed negative. The scenarios were deliberately linked to the Shared Socioeconomic Pathways framework, with BAU mapped to SSP2, DS to SSP4, FSS to SSP3 and DIV to SSP1, and the authors stress that the results are structured explorations of plausible futures rather than predictions.

The broader implications reach well beyond Ireland. The findings challenge the resilience of least-cost, globalised supply chains that have driven extreme regional specialisation in industrialised agriculture, and suggest that circularity can hedge farmers and energy consumers against trade disruptions and price volatility. All energy-focused and most feed-focused scenarios exceeded Ireland’s 2030 biomethane target of 5.7 terawatt-hours per year, though current progress toward that target remains slow, and the authors argue that a longer-term 2050 plan for anaerobic digestion within an integrated land use strategy could anchor durable investment. Bioenergy could also underpin carbon dioxide removal through capture and storage, provided grid upgrades and spatial planning place facilities within economic transport radii of sufficient feedstock. The central message is sober but constructive: only transformative change across agriculture, forestry, energy and food systems can deliver net zero, yet embedding circularity within that transformation converts a fragile climate strategy into a robust one, capable of withstanding the market shocks that the coming decades are almost certain to deliver.

Subject of Research: Interaction between circular bioeconomy strategies and net zero greenhouse gas pathways in agriculture and land use

Article Title: Circularity measures enhance resilience of net zero pathways for agriculture

Article References: Henn, D., Girón Domínguez, C., Martínez-Arce, A., Bishop, G., Duffy, C., Lind, V., & Styles, D. (2026). Circularity measures enhance resilience of net zero pathways for agriculture. Communications Earth & Environment, 7(1), Article 772. https://doi.org/10.1038/s43247-026-04052-3

Image Credits: AI Generated

DOI: 10.1038/s43247-026-04052-3

Keywords: circular economy, net zero, agriculture, anaerobic digestion, bioenergy, livestock feed, greenhouse gas emissions, land use, resilience, Ireland, food security, climate policy