Modelling national transformations to achieve the SDGs within planetary boundaries in small island developing states

Non-technical summary The Sustainable Development Goals (SDGs) provide an integrated and ambitious roadmap for sustainable development by 2030. National implementation will be crucial and there is an urgent need to understand the scale and pace of transformations to achieve the goals. There is also concern that achieving socio-economic objectives will undermine longer-term environmental sustainability. This study uses modelling to explore how different policy and investment settings can enable the necessary transformations, adopting Fiji as a use-case. Modest investment over the coming decade can deliver improved performance. However, far more ambitious actions are needed to accelerate progress while managing long-term trade-offs with environmental objectives. Technical summary This paper presents the results from a national scenario modelling study for Fiji with broader relevance for other countries seeking to achieve the SDGs. We develop and simulate a business-as-usual and six alternative future scenarios using the integrated (iSDG-Fiji) system dynamics model and evaluate their performance on the SDGs in 2030 and global planetary boundaries (PBs) and the ‘safe and just space’ (SJS) framework in 2050. Modest investment over the coming decade through a ‘sustainability transition’ scenario accelerates SDG progress from 40% to 70% by 2030 but fails to meet all SJS thresholds. Greatly scaling up investment and ambition through an SDG transformation scenario highlights possibilities for Fiji to accelerate progress to 83% by 2030 while improving SJS performance. The scale of investment is highly ambitious and could not be delivered without scaled-up international support, but despite this investment progress still falls short. The analysis highlights where key trade-offs remain as well as options to address these, however closing the gap to 100% achievement will prove very challenging. The approach and findings are relevant to other countries with similar characteristics to increase the understanding of the transformations needed to achieve the SDGs within PBs in different country contexts. Social media summary How can countries accelerate progress on the SDGs by 2030 while ensuring longer-term coherence with climate and sustainability thresholds?