From Complex Models to Shared Climate Choices: FeliXSim at ISDC 2026
From 20 to 24 July 2026, CHOICE researchers joined the International System Dynamics Conference in Delft, the Netherlands, to share new approaches for bringing human behaviour, lifestyle change and wider participation into climate and sustainability modelling.
A central contribution was the presentation “FeliXSim: An Interactive Simulation Environment for Global Systems Modeling in Climate and Sustainability Contexts,” delivered by Ryan Yi Wei Tan and Sibel Eker from IIASA.
Opening climate models to wider audiences
Integrated Assessment Models help researchers explore the long-term interactions between society, the economy, climate and the environment. Yet their complexity often limits their direct use to specialised modelling communities.
FeliXSim was developed to help close this accessibility gap. It is an open-source, browser-based Interactive Simulation Environment developed as an interface to the FeliX Integrated Assessment Model.
The tool focuses particularly on behaviour change and demand-side climate mitigation in the food system. Users can experiment with assumptions related to consumption, production, external drivers and uncertainties, and then explore possible outcomes for food, nutrition, land use, climate, fertiliser use, biodiversity and water.
Rather than presenting a single pathway, FeliXSim allows users to investigate different questions. For example, they can explore how dietary change may influence several sustainability outcomes or examine the behavioural and technological drivers that could support large-scale changes in food consumption.
The platform supports real-time scenario exploration and includes a structure–behaviour display, a survey function for capturing personal preferences and a multi-scenario mode for comparing more than two pathways. These features can support evidence-based policy deliberation and educational applications in systems thinking.
Exploring the power of food-system choices
Conference participants also had the chance to try FeliXSim for themselves during the 90-minute workshop, “Low-carbon behavior changes: Exploring food system scenarios with FeliXSim,” led by Sibel Eker on 24 July.
The session guided participants through the FeliX model, showing them how to explore its structure, run and compare scenarios, and make sense of feedback loops and long-term trends. No previous experience with System Dynamics or simulation software was needed, making the workshop open to people from a wide range of professional and academic backgrounds.
This hands-on approach reflects CHOICE’s goal of making Integrated Assessment Models easier to understand, more useful and more engaging. Through the FeliX Interactive Simulation Environment, stakeholders can explore how changes in food-system behaviour may influence climate and other sustainability outcomes, while gaining a clearer picture of the wider benefits of more sustainable food choices.
Bringing human behaviour into sustainability pathways
CHOICE-related discussions at the conference went beyond the digital interface itself.
The roundtable “Integrating Human Decision-Making and Behaviour in Modeling to Support Policy Design for Sustainability Transformation” brought together Merla Kubli, Sibel Eker, Etiënne Rouwette and Christoph Schünemann. It explored how theories from psychology, sociology and behavioural economics can be integrated into Systems Thinking and System Dynamics models.
Participants were invited to exchange practical experiences, identify existing behavioural approaches and contribute relevant literature. The discussion highlighted the importance of representing how people respond to policies and interventions—from individual decisions to broader societal transformations.
A further presentation by Etiënne Rouwette, Sibel Eker and Deepthi Swamy examined global food and energy scenarios driven by lifestyle changes. Their work introduces an endogenous lifestyle module into FeliX, modelling lifestyle change through opportunity, identity and experience effects and connecting these dynamics to food and energy demand.
The research shows why lifestyle change cannot be treated only as an external assumption. Different population groups may follow distinct demand pathways even under the same macroeconomic conditions, while the economic and demographic impacts of climate change can also affect lifestyle transitions.
Better engagement for better-informed choices
CHOICE works to improve the representation of behavioural change and actor heterogeneity in Integrated Assessment Models while opening these scientific tools to wider society.
The contributions at ISDC 2026 demonstrated how this can be achieved in practice: by combining scientifically rigorous modelling with accessible interfaces, participatory workshops and interdisciplinary dialogue.
FeliXSim does not remove the complexity of food-system transformation. Instead, it gives more people the opportunity to explore that complexity, understand connections and discuss possible pathways.
By making the consequences of different choices more visible, interactive simulation environments can help turn climate modelling into a shared space for learning, participation and more informed action.
Want to dive deeper? Explore the full presentation here.
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