A system dynamics model of social, economic, and environmental earth systems and their interdependencies.

The Full of Economic-Environment Linkages and Integration dX/dt (FeliX) model represents a full system dynamics perspective on the social, economic, and environmental sub-components of the Earth system.

Critical interdependencies among these systems are incorporated to recreate the complex dynamic behavior which characterizes the Anthropocene.

FeliX is a globally aggregate model that can be adapted and simulated easily and quickly to explore the global socio-economic-environmental dynamics.

About FeliX

FeliX is a system dynamics model that simulates complex interactions among 10 global systems: population, education, economy, energy, water, land, food (including diet change), carbon cycle, climate, and biodiversity. The model outcomes are determined by many interacting feedback loops within and between these systems as shown in the figure below.

Felix © Moallemi et al. (2022)

The model is calibrated to historical data available from the FAO, IEA, IRENA, the World BankUN Population Division and Wittgenstein Center for Demography and Global Human Capital. FeliX is a time-continuous simulation model across the time horizon 1900- 2100. The period 1900-2020 is the calibration period, varying across the model variables dependent on data availability, and the projection period is 2020-2100. FeliX scenario outcomes project on a global scale major stock changes (e.g., depletion of natural resources, accumulation of carbon dioxide in the atmosphere) as well as the aggregate consequences of policies and technologies (e.g., afforestation, emissions reduction) over time.

The first version of the model was developed by Felicjan Rydzak and Michael Obersteiner. Between 2014 and 2017, FeliX model maintenance and development has been led by Brian Walsh. Currently, the model maintenance and development is undertaken by Sibel Eker in various projects including WorldTrans to improve the representation of social systems and behavior changes in integrated assessment modelling.


  • The baseline scenario in FeliX maps to benchmark RCP and SSP outcomes, allowing for robust conclusions regarding the relative impact of a wide array of policies and technologies.
  • FeliX reveals important synergies and tradeoffs between developmental and environmental goals, hence enables comprehensive assessment of sustainable development goals (SDGs). 
  • Expected demand for food, feed, and fiber is at the heart of the model, giving insight into trends in land use change as well as the allocation of other resources in the absence of environmental interventions.
  • Complex linkages among model sectors reveal indirect, potentially unintended, consequences of both targeted and general interventions.
  • FeliX enables exploring the implications of population heterogeneity and societal change for low-carbon lifestyles.


FeliX is a global system dynamics model developed for the purpose of understanding human-earth system interactions. Therefore, model development focuses on including main feedback loops with a broad scope and generating model behavior endogenously, rather than a detailed representation of the physical and socioeconomic relationships and material flows. Furthermore, the global view requires aggregating the existing heterogenous information to mimic relationships and impacts on a global level and over long-time horizons.

Some of the phenomenon included in the FeliX model were already well studied and mathematically described. For example, specific model structures on phenomena closely related to climate include atmospheric concentration of CO2 caused by human activities and the associated carbon cycle. The basic dynamics of the climate system have been intensively researched and described in the literature (Oeschger et al. 1975, Rotmans 1990, Nordhaus 1992, Fiddaman 1997), which allowed for adoption of quantitatively expressed relations of the system components in the FeliX model. In cases where such relations have not been quantitatively established, group model building sessions (Vennix 1996, Andersen et al. 1997) or online research was conducted, and subject matter experts defined and quantified the relations of interest. The model is subject to updates, as the new information and data on climate impacts becomes available to the global research community.

Selected publications with FeliX

Moallemi, E.A., Eker, S. , Gao, L., Hadjikakou, M., Liu, Q., Kwakkel, J., Reed, P.M., Obersteiner, M., Guo, Z., & Bryan, B.A. (2022). Early systems change necessary for catalyzing long-term sustainability in a post-2030 agenda. One Earth 5 (7) 792-811. 10.1016/j.oneear.2022.06.003.

Walsh, B. , Ciais, P., Janssens, I.A., Penuelas, J., Riahi, K. , Rydzak, F., van Vuuren, D.P., & Obersteiner, M. (2017). Pathways for balancing CO2 emissions and sinks. Nature Communications 8 e14856. 10.1038/ncomms14856.

Model Report and Technical Documentation:

Rydzak, F., Obersteiner, M., Kraxner, F., Fritz, S., and McCallum, I. (2013). FeliX3 – Impact Assessment Model Systemic View Across Societal Benefit Areas Beyond Global Earth Observation. International Institute for Applied Systems Analysis (IIASA