Model scope and methods - WITNESS
Model scope
WITNESS stands for "World environmental ImpacT aNd Economics ScenarioS".
It is a global Integrated Assessment Model (IAM) framework, covering the world globally (regionalization in progress and first level sectorization completed). The framework covers MacroEconomics, Energy, Materials, Natural resources, Environment, Population and Public Policies - mostly endogenous and fully coupled (i.e. taking into account all the feedback loops representing mutual interactions between models).
Most of the models are based on equations rather than data analysis and extrapolation, and the feedback loops generated by models interdependencies are efficiently and largely automatically tackled by the underlying simulation platform specifically developed to support it. This simulation platform called SoSTrades (which stands for "System of Systems Trades"), and can by the way be used independently as a generic and powerful Multi-Disciplinary Analysis and Optimization ( MDAO ) simulation platform.
The primary goal of WITNESS is to enable collaborative exploration of potential transition paths through simulation, pinpointing the key drivers that could steer these changes and the importance of feedback loops effects. Such a joint exploration aims to foster consensus on target trajectory envelopes, which is crucial for rallying a critical mass of stakeholders. Such collective agreement and engagement are seen as instrumental in successfully transitioning complete ecosystems.
Additionally, there’s an emphasis on risk estimation. This involves measuring the deviation between the planned trajectory and the worst possible scenarios, providing a quantitative assessment of risks associated with the transition. This metric serves as a vital tool for decision-makers to evaluate and manage potential uncertainties and challenges that may arise during the transition period.
This simulation platform called SoSTrades (which stands for "System of Systems Trades"), and can by the way be used independently as a generic and powerful MDAO simulation platform and is an extension of the specialized GEMSEO library.
WITNESS framework
WITNESS applies complex system of systems (1) simulation techniques to IAM modelling, applying a system engineering approach starting from the high level system view presented in the picture above with their interactions (more detail in the section "Model concept, solver and details").
This methodology allows easy and modular refinement of various systems, as well as rigorous handling of all the interactions and feedback loops between them. It also allows to leverage a full range of numerical multi-disciplinary analysis and optimization (MDAO) methods and tools to build a complete world transition model.
For example in the basic WITNESS framework, an MDO controller is optimizing ventilation of available investment from Macro-economy to various Energy production techniques in Energy system, in order to maximize energy production while minimizing emissions under resources and materials constraints (more details here or here).
SoSTrades simulation platform
SoSTrades is a multi-purpose and generic simulation management and execution platform, designed to explore complex system of systems scenarios in a collaborative way. It provides a a multi-user web front-end and cloud scalable backend to run and couple containerized models.
The model themselves are written in (or accessed through) Python language and handling their interactions is largely automated, facilitating evolutions or additions of new models.
Development team
WITNESS and SoSTrades are part of Transition analysis project of the Open Source for Climate, part of the FINOS initiative from the Linux Foundation.
Their development is supported by Capgemini, which is also providing industrial grade deployment and support option, as well as several extensions to derive from WITNESS generated transition scenario various enterprise strategy models.
More details can be found on witness4climate.org website.
(1) Charaf Eddine Dridi, Belala Faiza. System of Systems Modelling: Recent work Review and a Path Forward. - ICAASE’20, Oct 2020, Constantine, DZ, France. ffhal-04227335f
Note: The documentation of WITNESS is 'in preparation' and is not yet 'published'!| Corresponding documentation | |
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| Previous versions | |
| No previous version available | |
| Model information | |
| Model link | |
| Institution | Open-Source for Climate (OS-C), N/A, https://os-climate.org/transition-analysis/., Linux Foundation (LF), N/A, https://www.linuxfoundation.org/. |
| Solution concept | Systems dynamics based approach |
| Solution method | OptimizationSimulation-based optimization |
| Anticipation | |