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Modelling Degrowth

The Contribution of IAMs and Ecological Macroeconomic Models to Assess the Feasibility of Degrowth pathways

The challenges related to environmental degradation in general and climate change in particular, as well and increasing inequality impose to the scientific community the burden to produce knowledge capable of stimulating truly transformative actions. “Degrowth” is gaining momentum as a purposeful strategy to stabilize economies and achieve social and ecological goals. However, there is still a lack of quantitative models that are able to simulate and anticipate the multiple direct and side effects in terms of wellbeing, unemployment, climate change, policies, etc. The complexity of the issue at hand and the need for real actions lead to the definition of alternative methods, grounded on a more solid epistemological basis.
In this regard, we
propose a Session on the last Integrated Assessment Models (IAMs) generation
models and Ecological Macroeconomics Models that connect the socio-economic
structures within the climate-ecological boundaries. These models highlight
that a deep understanding of complex systems leads to the development of
multi-dimensional models, where the economy is seen as hierarchically
subordinated to the ecological systems, and to the inclusion of stakeholders to
define coordinated and shared solutions. Modelling Degrowth pathways require some
specificities with relation to more traditional modelling; notably a detailed
and comprehensive representation of behavioral changes, structural changes at
economic and social level, a set of heterodox policies to be modelled, explicit
representation of inequalities, etc.
IAMs are typically used
to evaluate and compare alternative scenarios on the basis of the
"what-if" conditions, suggesting that multiple policies are needed to
reach multiple (possibly contrasting goals). Attention will be given to the
possible limits of modelling (e.g., validation, limits to the complexity of the
model, data requirement and computational costs, temporal and spatial scales,
etc.) of IAMs and how to overcome them by integrating qualitative analyses to
make IAMs effective in promoting political and behavioral changes.
The main objectives of
the Special Session will be to share results from last generation cutting-edge
models simulating Degrowth scenarios, and to foster the discussion on the
potentialities and limits of quantitative modelling for analysing Degrowth
The contributors will
present the result of the WILIAM model developed in the LOCOMOTION H2020
Project but presentation from different models are welcomed. We also accept
contributions which address from a theoretical/conceptual point of view the
potentialities and limits of quantitative modelling for analysing Degrowth

This session will also contain the following presentations:
Literature review of policies for the simulation of Degrowth scenarios in Integrated Assessment Models
Co-authors: Oriane Denantes, Nathalie Wergles, Tommaso Brazzini, Clara Yiting Lauer, Iñigo Capellán-Pérez
Despite Degrowth is increasingly gaining ground as an alternative sustainability storyline and an ample theoretical literature is being developed, quantitative modelling has been to date scarce and with divergent findings, which hinders the efficacy, feasibility and robustness of the approach. Quantitative modelling is a key methodology for policy advice aiming at anticipating outcomes which may help guide policy-decisions today. In this work, we have performed a systematic literature review of models simulating Degrowth scenarios with a focus on the types of policies considered. From the analysis of the 29 reviewed studies we can conclude that: (1) a minority focuses on "postgrowth pathways", i.e. how to get there and what the implications would be, while the majority explores aspects of an already existing postgrowth society . (2) Heterogenity: different types of models (stylized theoretico-quantitive, macroeconomic models, IAMs, etc.), geographical scope; changes driven top-down (governmental) vs bottom-up (civil society); steady state economy within a capitalist society vs non-capitalist systems. This heterogeneity reflects the diversity in the postgrowth visions. (3) All studies cover only partially the 10 core Degrowth policy proposals identified by Fitzpatrick et al. (2022) in the recent review (Exploring degrowth policy proposals: A systematic mapping with thematic synthesis. Journal of Cleaner Production 365, 132764). However, almost al l core Degrowth policy proposals are modelled at least in 1 of the reviewed works. On the other hand, the number of policy measures and targets implemented is very low compared with the portfolio of Fitzpatrick et al., with an average of 4.3 per scenario (with a minimum of 1 and a maximum of 12 ). The most often modelled policies are: working time reduction (8 studies), change in the energy mix (increase in RES) (8), basic income (6), decrease in population growth (5) and decrease in GDP (5). This suggests the viability of increasing the amount of policies represented in models (although the very different scope of the reviewed models would likely impede translating approaches from one model to another), as well as the necessity to increase the amount of policy measures and targets. An effort should be done by the Degrowth Modelling community to comprehensively include the full portfolio of core polici es from the Degrowth literature across all sectors and economic agents at a global level in a coordinated way. A selective implementation of the policies would lead to rebound effects and perverse dynamics given the interconnections between the different economic sectors and countries. Policy parametrization should be performed against goals. The need of expanding the set of represented policies should be assessed after performing simulations.

Modelling behavioural change for degrowth in Integrated Assessment Models (IAMs)
Co-authors: Paola López-Muñoz, David Álvarez-Antelo, Katharina Koller, Paolo Massa, Lisa Mo Seebacher
Behavioural change is considered one of the demand-side strategies for achieving sustainable development pathways. People change their behaviour by altering the way they consume or live, causing a reduction in the use of resources or waste generation. Citizens are commonly encouraged to avoid, shift, or improve their behaviour to benefit climate adaptation or mitigation. Yet, it is still lacking an holistic understanding of behavioural change as well as of its interactions with ecological, economic, political, and social systems. Moreover, research on behavioural change is often focused on consumption and individual responsibility, instead of contributing to a collective degrowth strategy, including all responsible actors. Here, we develop a new modelling framework that consists of integrating behavioural change in an Integrated Assessment Model (IAM) called WILIAM (‘WIthin Limits’ IAM). WILIAM is a complex multi-sectoral and multi-regional model based on system dynamics which represents a wide variety of economy, society and environment interactions and feedback loops. Through this work, the model is qualitatively informed by a literature review on degrowth behavioural change measures and the collective and individual drivers and barriers to their adoption. After, these relationships are translated into mathematical equations and indicators that are included in the model. This modelling framework provides findings on both intentions and impacts of transformative behavioural change: we focus on systemic enablers and constraints behind behavioural change towards degrowth and also evaluate the consequences in terms of environmental and social impacts. Thus, our work represents a further contribution to the systematic planning and evaluation of degrowth as a political project.


Day: 2023-08-31
Start time: 12:00
Duration: 01:30
Room: ZV-8-8
Type: Special Session
Theme: Climate (in)justice


Concurrent Sessions