Social actors and unsustainability of agriculture

•Unsustainability of agriculture can derive from decisions and choices by various social actors.•Actor-based indicators that characterize unsustainability processes can guide learning and adaptive responses.•Policies, incentives and information supply can support farms’ adjustments and social actors’ behaviour change.•Process indicators support tracking progress and effectiveness of responses to unsustainability issues.•Social learning and debate are key to sustainable multifunctional agricultural landscapes. Social actors can strongly affect the sustainability of agricultural operations by influencing farmers’ decisions and choices. Such actors include: (1) loss-making investors who abandon farms due to low returns, (2) angry neighbours negatively affected by farming operations and engaging in silent or active conflict, (3) dissatisfied customers at the end of the value chain who reject the products and shift to alternative providers, and (4) overacting regulators who over-regulate farm activities. A higher order sustainability concept considers the ability of farms to adapt and learn from early signs of threats. A number of response paths based on policies, incentives and information supply have been developed to support learning and adjustments. Emphasis on the nested-scales relations of incremental sustainability and sustainagility, in addition to the more commonly articulated ecological threshold perspective, helps identify key indicators that characterize unsustainability processes across countries and contexts. A dynamic systems understanding also assists selection of process indicators focused on response paths that complement result-oriented approaches in current sustainability assessment frameworks.