Sustainable Living in Systems Change
Authors:   , van den Berg Nicole Jane 
Published: May 2023

Anthropogenic greenhouse gas emissions have increased almost continuously since 1850, and it has been unequivocally proven to contribute to climate change. In the Paris Agreement of 2015, countries agreed to limit the global mean temperature increase to well below 2°C, possibly even 1.5°C, compared to the preindustrial level. Traditionally, changes in energy supply have been explored and considered extensively as solutions to combat climate change. Yet, there has been much less focus on demand-side changes through lifestyle and behavioural changes. However, this has changed in the last few years, with increasing attention to sustainable lifestyles and behaviour, for example, in the UNEP Emission Gap Report and IPCC AR6. This research aims to show how to improve the representation of lifestyle changes in Integrated Assessment Models (IAMs), to establish the possible role of lifestyle changes in climate change mitigation strategies. This thesis identifies key insights from existing literature on different approaches for analysing lifestyle changes. These insights include the harmonisation of lifestyle-related terms, different perspectives on analysing lifestyles, the broad ranges of lifestyle changes that can be modelled, the trade-offs between different modelling approaches and the tools that could help analyse the outcomes of lifestyle changes. This thesis also developed the ASIF* decomposition tool to distinguish between impacts from consumption and technology changes in the analysis of future scenarios. Another part of the thesis analyses current lifestyles compared to future emissions consistent with climate targets. This analysis shows how heterogeneous segments within and between regions show a variety of lifestyles and contexts that affect emissions, and large consumer segments in Japan are close to the transport-related emission levels in a 2°C climate scenario in 2050. A vital part of the thesis is the set of developed SLIM (Sustainable Living in Models) scenarios across two critical uncertainties: more individualistic or collectivist values; and more centralised or distributed support for sustainable lifestyles. Four scenarios emerge, leading to unique, sustainable futures and just transitions. Firstly, the qualitative SLIM scenario narratives illustrate how structural support and value systems shape lifestyles differently and change dynamically in response to enablers and societal shifts. The scenario narratives identify the extent and speed of lifestyle changes for modelling the SLIM scenarios, with regional differentiation and equity considerations. The emission pathways show the implications of the SLIM scenarios towards sustainable living and highlight that lifestyle changes contribute substantially to climate change mitigation, mostly with larger systems change, to achieve transformative outcomes. More specifically, lifestyle changes could reduce passenger transport and residential emissions by about 39% for Global North regions and 27% for Global South regions in 2050 compared to a scenario based on current trends. These scenarios can help guide strategic dialogue and global climate change mitigation decisions and actions by considering lifestyle change in the context of larger systems change.