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Zusammenfassung:
Background
Food systems are important drivers of planetary boundary transgressions at both global and local scales. Growing evidence shows that when multiple planetary boundaries are transgressed simultaneously, such transgression can amplify their negative consequences on Earth system processes. Therefore, it is essential to scrutinise global boundary transgressions at the local scale.
Methods
This study assessed future planetary boundary transgressions under different food system-transformation (EL2) and combined food system-transformation and climate mitigation (ELM) scenarios, both on global and local scales, by defining ten global and eight local boundary indicators and simulating them using the Integrated Model to Assess the Global Environment framework.
Findings
Our results identified hotspots of local boundary transgressions across scenarios. Policies addressing the food system (such as dietary change, productivity increase, and halving food loss and waste) can help to reduce future transgressions. Dietary change results in the largest reductions in the land-system change (70%) and biosphere integrity (69%) domains. Policies with a focus on agricultural productivity improve the biogeochemical flows (phosphorus) domain (92%), and mitigation measures drive most of the improvements in freshwater change (62% blue, 82% green), climate change (67%), and aerosol loading (75%). On a global scale, there are no trade-offs between the EL2 and ELM scenarios, but trade-offs can occur on a local level, with large regional differences in boundary transgressions. Grid cells with six or more local boundary transgressions account for 6·1% of the total land area under business-as-usual, 4·5% under EL2, and 3·1% under ELM, as compared with 4·9% in the historical reference period 2020.
Interpretation
Policies addressing both the food system and climate change can be effective in simultaneously reducing boundary transgressions across scenarios, although a multiscale approach can help to identify regional trade-offs that remain hidden at global scales.
