Defining a Sustainable Development Target Space for 2030 and 2050

By adopting the Sustainable Development Goals (SDGs), countries worldwide agreed to an agenda for achieving a prosperous, socially inclusive and environmentally sustainable future for all1. This ambition, however, also exposes a critical knowledge gap since science-based insights on how to achieve the 17 SDGs simultaneously are lacking. Quantitative goal-seeking scenario studies could enable exploration of the systems' transformations required to achieve the SDGs, but this requires a clear definition of the "target space". The 169 targets and 232 indicators defined by the international community for monitoring SDG implementation cannot be directly used for this purpose. Here, we define a streamlined set of well-defined, science-based indicators and associated target values that is quantifiable and actionable to make quantitative scenario analysis meaningful, relevant (i.e. reflecting societal goals), and yet simple enough to keep analysis transparent and communicable. The set of 36 targets is based on the UN 2030 Agenda, other existing multilateral agreements and insights from sustainability science and expert assessment, and it includes 2050 as an additional longer-term reference point. Thus, this target space provides a strategic focus to guide the scientific community in developing new global sustainable development pathways.