RESUMEN
The topic of SDG interactions is a relatively new research area with many knowledge gaps. Some of these gaps are addressed in this summary of a Special Feature of Sustainability Science, including new findings and emerging issues on (1) the characteristics of SDG interactions; (2) methods/methodology to analyse these interactions; and (3) the elaboration of drivers that influence SDG synergies. The importance of scale is clear in two emerging issues. First, there is evidence of a disconnect between national planning for SDGs and their implementation at the local scale which is leading to SDG trade-offs between these scales. Second, the concept of a "critical transition zone" is introduced where SDG trade-offs pose a particular challenge to SDG implementation. These are areas (e.g., peri-urban and forest margin areas in the Global South) undergoing rapid biophysical and/or socio-economic changes and inhabited by populations especially vulnerable to these changes. While trade-offs occur among the SDGs, there are also many examples of synergies which provide opportunities for advancing multiple goals. To distinguish between synergies and the actions that exploit them, the term "synergy driver" is introduced to refer to policies and measures that positively advance two or more goals. Several examples of synergy drivers are presented, including sustainable global supply chains, people-centred early warning systems, and joint conservation-public health programmes. To make synergy drivers relevant to the broader policy community, the research community (working with stakeholders) should first consolidate knowledge about these drivers and then evaluate their effectiveness/applicability to different policy settings.