A simulation-based approach for investigating the dynamics of rebound effects in the circular economy: A case of use-oriented product/service system.

Current research in Circular Economy (CE) fails to address the occurrence of Rebound Effects (RE), which are systemic and behavioural responses to the implementation of interventions hindering the potential sustainability benefits. This paper aims to advance the academic discussion and the practical consideration of RE by exploring the potential of using System Dynamics (SD) to enable the ex-ante identification of potential RE of CE initiatives. A five-stage simulation-based approach for the identification and mitigation of potential rebound effects (AIMRE) is proposed. Its application is demonstrated in a use-oriented product/service system (PSS) case focused on a high-end dress rental service. The AIMRE enables the representation of the magnitude and reasons for RE occurrence through 14 scenarios. The finding highlights the importance of considering the interplay between consumers' and companies' decision-making processes in quantifying, understanding, and mitigating RE occurrence.

Dynamic implications of the biological link between bovine milk and meat production for operationalizing the planetary health diet.

The EAT-Lancet planetary health diet (PHD) provides guidelines on a global scale and calls for red meat consumption to be halved. Operational PHD guidelines at country level have yet to be determined. Here we argue that the biological link between milk and bovine-meat production must be considered when operationalizing the globally calculated PHD to national contexts. Using a stylized computer simulation model rooted in a food system approach, we explore the impact of dietary scenarios on milk and bovine-meat production and show that ignoring this biological link can lead to substantial imbalances between national dietary guidelines and production outcomes and potentially lead to food waste. Furthermore, we assess current national dietary guidelines in Europe and find that most disregard this biological link and are incompatible with the PHD, with implications for policymakers and consumers to consider when adapting the PHD in national contexts.

Co-creating obesity prevention policies with youth: Policy ideas generated through the CO-CREATE project.

Despite growing recognition of the importance of applying a systems lens to action on obesity, there has only been limited analysis of the extent to which this lens has actually been applied. The CO-CREATE project used a youth-led participatory action research approach to generate policy ideas towards the reduction of adolescent overweight and obesity across Europe. In order to assess the extent to which these youth-generated policy ideas take a systems approach, we analyzed them using the Intervention Level Framework (ILF). The ILF ascribes actions to one of five system levels, from Structural Elements, the least engaged with system change, up to Paradigm, which is the system's deepest held beliefs and thus the most difficult level at which to intervene. Of the 106 policy ideas generated by young people during the CO-CREATE project, 91 (86%) were categorized at the level of Structural Elements. This emphasis on operational rather than systems level responses echoes findings from a previous study on obesity strategies. Analyzing the distribution of systems level responses using the ILF has the potential to support more effective action on obesity by allowing identification of opportunities to strengthen systems level responses overall.

System dynamics simulation models on overweight and obesity in children and adolescents: A systematic review.

It has increasingly been recognized that developing successful obesity prevention policies and interventions requires understanding of the complex mechanisms driving the obesity pandemic and that models could be useful tools for simulating policies. This paper reviews system dynamics simulation models of mechanisms driving childhood overweight and obesity and/or testing of preventive interventions. A systematic literature search was conducted in six databases from inception to January 2023 using terms related to overweight/obesity, children, and system dynamics. Study descriptives, mechanisms, and where to intervene (the leverage points), as well as quality assessments of the simulation models were extracted by two researchers into a predetermined template and narratively synthesized. Seventeen papers describing 15 models were included. Models describing the mechanisms ranged from only intrapersonal factors to models cutting across multiple levels of the ecological model, but mechanisms across levels were lacking. The majority of interventions tested in the simulation models were changes to existing model parameters with less emphasis on models that alter system structure. In conclusion, existing models included mechanisms driving youth obesity at multiple levels of the ecological model. This is useful for developing an integrated simulation model combining mechanisms at multiple levels and allowing for testing fundamental system changes.

Understanding the dynamics emerging from the interplay among poor mental wellbeing, energy balance-related behaviors, and obesity prevalence in adolescents: A simulation-based study.

Both obesity and poor mental wellbeing have a high prevalence in European youth. Adolescents in six countries identified mental wellbeing factors as main drivers of youth obesity through systems mapping. This study sought to (1) explore the dynamics of the interplay between poor mental wellbeing, energy balance-related behaviors, and adolescent overweight and obesity prevalence and (2) test the effect of intervention point scenarios to reduce adolescent obesity. Drawing on the youth-generated systems maps and a literature synthesis, we built a simulation model that represents the links from major feedback pathways for poor mental wellbeing to changes in dietary, physical activity, and sleep behaviors. The model was calibrated using survey data from Norway, expert input, and literature and shows a good fit between simulated behavior and available statistical data. The simulations indicate that adolescent mental wellbeing is harmed by socio-cultural pressures and stressors, which trigger reinforcing feedback mechanisms related to emotional/binge eating, lack of motivation to engage in physical activity, and sleep difficulty. Targeting a combination of intervention points that support a 25% reduction of pressure on body image and psychosocial stress showed potentially favorable effects on mental wellbeing-doubling on average for boys and girls and decreasing obesity prevalence by over 4%.

Applying a systems perspective to understand the mechanisms of the European School Fruit and Vegetable Scheme.

BACKGROUND: For the past two decades, the percentage of European children who consume fruit daily has remained at around 40%, despite numerous school-based policy efforts and interventions. This study aimed to apply a systems approach to provide an integrated perspective of the mechanisms of the European School Fruit and Vegetable Scheme (the Scheme) to understand better how to increase its long-term impact on children's fruit and vegetable consumption. METHODS: We developed a causal loop diagram by synthesizing peer-reviewed articles and national government documents related to the Scheme, following the conceptualization steps of system dynamics. The initial causal loop diagrams were then validated in three stages by consulting with experts (two individuals and a group) in school-based fruit and vegetable programmes, children's fruit and vegetable consumption and the Scheme, using disconfirmatory interview guidelines. RESULTS: The findings suggest that a central self-reinforcing mechanism through which children socialize during fruit and vegetable consumption is critical in the habituation process. Additionally, the initial increase in children's fruit and vegetable consumption following the Scheme implementation is due to growth in three self-reinforcing loops related to motivation and capability mechanisms; however, this trend gradually slows and stops due to four balancing feedback loops with alternative goals related to opportunity mechanisms that reach their limits. CONCLUSIONS: The scheme's design should incorporate activities that align the objectives of the implementers and recipients of the Scheme at all levels. This alignment should provide children with ongoing opportunities to consume fruits and vegetables and strengthen the motivation and capability mechanisms.

Conceptual frameworks linking agriculture and food security.

Many conceptual frameworks have been developed to facilitate understanding and analysis of the linkages between agriculture and food security. Despite having usefully guided analysis and investment, these frameworks exhibit wide diversity in perspectives, assumptions and application. This Review Article examines this diversity, providing an approach to assess frameworks and suggesting improvements in the way they are specified and applied. Using criteria-based systems modelling conventions, we evaluate 36 frameworks. We find that many frameworks are developed for the purpose of illustration rather than analysis and do not clearly indicate causal relationships, tending to ignore the dynamic (stability) dimensions of agriculture and food security and lacking clear intervention points for improving food security through agriculture. By applying system modelling conventions to a widely used framework, we illustrate how such conventions can enhance the usefulness of a framework for overall illustration purposes, delineate hypotheses on agriculture-food security links and examine potential impacts of interventions.

Application of the malaria management model to the analysis of costs and benefits of DDT versus non-DDT malaria control.

INTRODUCTION: DDT is considered to be the most cost-effective insecticide for combating malaria. However, it is also the most environmentally persistent and can pose risks to human health when sprayed indoors. Therefore, the use of DDT for vector control remains controversial. METHODS: In this paper we develop a computer-based simulation model to assess some of the costs and benefits of the continued use of DDT for Indoor Residual Spraying (IRS) versus its rapid phase out. We apply the prototype model to the aggregated sub Saharan African region. For putting the question about the continued use of DDT for IRS versus its rapid phase out into perspective we calculate the same costs and benefits for alternative combinations of integrated vector management interventions. RESULTS: Our simulation results confirm that the current mix of integrated vector management interventions with DDT as the main insecticide is cheaper than the same mix with alternative insecticides when only direct costs are considered. However, combinations with a stronger focus on insecticide-treated bed nets and environmental management show higher levels of cost-effectiveness than interventions with a focus on IRS. Thus, this focus would also allow phasing out DDT in a cost-effective manner. Although a rapid phase out of DDT for IRS is the most expensive of the tested intervention combinations it can have important economic benefits in addition to health and environmental impacts that are difficult to assess in monetary terms. Those economic benefits captured by the model include the avoided risk of losses in agricultural exports. CONCLUSIONS: The prototype simulation model illustrates how a computer-based scenario analysis tool can inform debates on malaria control policies in general and on the continued use of DDT for IRS versus its rapid phase out in specific. Simulation models create systematic mechanisms for analyzing alternative interventions and making informed trade offs.