Trade-offs are unavoidable in multi-objective adaptation even in a post-Paris Agreement world

In a post-Paris Agreement world, where global warming has been limited to 1.5 or 2 °C, adaptation is still needed to address the impacts of climate change. To reinforce the links between such climate actions and sustainable development, adaptation responses should be aligned with goals of environmental conservation, economic development and societal wellbeing. This paper uses a multi-sectoral integrated modelling platform to evaluate the impacts of a + 1.5 °C world to the end of the 21st century under alternative Shared Socioeconomic Pathways (SSPs) for Europe. It evaluates the ability of adaptation strategies to concurrently improve a range of indicators, relating to sustainable development, under the constraints imposed by the contrasting SSPs. The spatial synergies and trade-offs between sustainable development indicators (SDIs) are also evaluated across Europe. We find that considerable impacts are present even under low-end climate change, affecting especially biodiversity. Even when the SDIs improve with adaptation, residual impacts of climate change affect all the SDIs, apart from sustainable production. All but one of the adaptation strategies have unintended consequences on one or multiple SDIs, although these differ substantially between strategies, regions and socio-economic scenarios. The exception was the strategy to increase social and human capital. Other strategies that lead to successful adaptation with limited unintended consequences are those aiming at adoption of sustainable behaviours and implementation of sustainable water management. This work stresses the continuing importance of adaptation even under 1.5 °C or 2 °C of global warming. Further, it demonstrates the need for policy-makers to develop holistic adaptation strategies that take account of the synergies and trade-offs between sectoral adaptation strategies, sectors and regions, and are also constrained by scenario context to avoid over-optimistic assessments.