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.

Artificial-satellite © IIASA

About FeliX

The model consists of over 1,300 elements including 91 stocks. Its outcomes are determined by many interacting feedback loops encompassing eight model sectors:

  1. Economy
  2. Energy
  3. Carbon Cycle
  4. Climate
  5. Biodiversity
  6. Water
  7. Population
  8. Land Use

Wherever possible, elements and stocks are calibrated to historical data available from the FAO, IEA, and UNIHP.

After calibration, FeliX scenario outcomes project on a global scale major stock changes (e.g., depletion of natural resources, accrual of carbon dioxide in the atmosphere) as well as the aggregate consequences of policies and technologies (e.g., afforestation, emissions reduction) over time.

The model was created by ESM Research Scholar Felicjan Rydzak.

Between 2014 and 2017, FeliX model maintenance and development has been led by ESM Research Scholar Dr. Brian Walsh. Currently, the model maintenance and development is undertaken by ESM Research Scholar Dr Sibel Eker.


  • 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 (MDG) and environmental (SDG) goals, as well as among the 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 in the context of dietary change.


While working on development of the FeliX model, which is supposed to constitute a ‘mock-up’ of a complex Earth system, a number of decisions, setting the boundaries of the model had to be made. It is rather impossible to model the Earth system in all details.

Thus, it had to be decided what phenomenon will become a part of the model in the sense of physical resources (e.g. population, forest, fossil fuels resources) and flows (e.g. birth rate, deforestation, oil discovery) as well as mechanisms and decisions controlling the change (flows) of resources over time (e.g. fertility, competition for agricultural land, investments in oil discovery and recovery).

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, Goudriaan and Ketner 1984, Bolin 1986, Rotmans 1990, Nordhaus 1992, Fiddaman 1997), which allowed for adoption of quantitatively expressed relations of the system components in the FeliX model structure. In cases where such relations have not been quantitatively established, group model building sessions (Richardson and Andersen 1995, Vennix 1996, Andersen et al. 1997) or online research was conducted, and subject matter experts defined and quantified the relations of interest and constructed parts of the model.

The chosen elements of the FeliX model had to relate to specific societal benefits areas since they were the focus of the studies.

The model boundaries could not be too narrow though. The assumption behind the System Dynamics model is that the model behavior is generated endogenously. That premise forced an internal integrity of the model in a sense of extent of the model (how many phenomena to include) but also in a sense of model details.

As necessary the reported phenomenon had to be scaled-up to a global level to be consistent with the model perspective.

The next challenge of the modeling work was to assimilate the many heterogeneous sources of information in studies carried out in the area of Earth observation into an integrated global impact study.

The primary sources of information were direct results from similar models, impact figures from published articles and sector reports, and information obtained from expert interviews or online research.

Generally, Value of Information (VoI) studies are confined to a particular place, time and sector. Impacts are rarely reported on global aggregates or carried out using a wider economic system representation to account for the many potential feedbacks. Therefore, existing information had to be adapted through aggregation to mimic effects on a global level and over long-time horizons.

Felix_model © IIASA


Rydzak, F. & Obersteiner, M. (2009). System dynamics model for analyzing and measuring the benefits of Global Earth Observation. In: 33rd International Symposium on Remote Sensing of Environment, ISRSE 2009, 4th-8th May 2009, Stresa; Italy.