Dr Yoko Nagase

The ecological and societal problems caused by product obsolescence and consumerism in modern economies constitute a ‘wicked human‐made problem’ of significant magnitude. Current (old) ways of thinking cannot address these problems. Accordingly, in this paper, we critically explore the novel idea of integrated personhood and worldviews to theorise research on self‐repairers and their repair behaviours to extend product lifetimes. We conducted a structured and systematic review of published work (n=183) to identify the conceptual content of the field to inform our theorisation. Our findings highlight three key issues. Firstly, constricted theorisation undermines understanding of self‐repairers and their product lifetime extension (and spillover) behaviours. Secondly, the underlying conceptual complexity is typically underestimated. Thirdly, the dominance of voluntarist and deterministic studies impedes new directions in research. From our review, an integrated worldview‐personhood framework emerges that can deepen understanding of avant‐garde self‐repairers’ engagement with product lifetimes.

This paper presents a novel modelling approach to deriving the social discount rate, by 

applying the power mean to certainty-equivalent (CE) consumption, where the power term

reflects the degree of aversion to uncertainty regarding future consumption. The numerical

exercise based on our theoretical model demonstrates that a declining term structure depends

on project appraisers having a substantial degree of aversion to uncertainty. Moderate

aversion, consistent with official discount rate guidance from the European Commission,

would favour a gradualist approach towards climate change mitigation.

This article documents trans-disciplinary collaboration between system dynamics (SD) practitioners and economists to produce knowledge useful for studying ecological-economic systems. The article introduces a multi-sector, ecological-economic model (EEM) of population-resource dynamics. Incorporating key concepts from economics on markets and prices, the model shows that SD models are able to represent the complex dynamics of an EEM, including out-of-equilibrium states and adaptation that strive to find new equilibria more realistically. The sensitivity analyses produce important implications, including the major finding that model behavior varies significantly with the degrees of price adjustment times. This finding justifies the Meadows et al., Limits to Growth model which omits an endogenous price mechanism, and also suggests that further research on non-instantaneous price adaptation mechanisms is needed. The article encourages modelers to incorporate out-of-equilibrium aspects of an economic system as appropriate, and highlights the potential for SD practitioners to contribute to economics, especially ecological economics.

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In order to cope with the increasing scarcity of final dump sites
for household wastes, the UK recently introduced an environmental
policy targeted at the firms that produce and sell products that
generate packaging wastes. This policy requires such businesses to
hold predetermined numbers of tradable credits called “Packaging
waste Recovery Notes” (PRNs). This article provides insights into
the economic implications of such a policy through a simple analytical
model of a recyclable product and the PRN markets. Our analysis
yields two particularly interesting results. First, an increase in the
required recycling rate dampens the output and landfill waste levels,
while the effect on the level of recycling activities is ambiguous.
Second, an increase in the landfill tax always leads to an increase in
the landfill waste. We also discuss how the socially optimal landfill
tax in the presence of the PRN market should be chosen.

In order to cope with the increasing scarcity of final dump sites for household wastes, the UK recently introduced an environmental policy targeted at the firms that produce and sell products that generate packaging wastes. This policy requires such businesses to hold predetermined numbers of tradable credits called “Packaging waste Recovery Notes” (PRNs). This article provides insights into the economic implications of such a policy through a simple analytical model of a recyclable product and the PRN markets. Our analysis yields two particularly interesting results. First, an increase in the required recycling rate dampens the output and landfill waste levels, while the effect on the level of recycling activities is ambiguous. Second, an increase in the landfill tax always leads to an increase in the landfill waste. We also discuss how the socially optimal landfill tax in the presence of the PRN market should be chosen.

This paper provides a comprehensive analysis of Brander and Taylor’s (1998) model and its descendants from the following perspectives: population growth, substitutability, innovation, capital accumulation, property rights and institutional designs, and modelling approach. This survey aims to contribute to a better understanding of population and resource dynamics models in general and facilitate further application of the model framework to relevant circumstances.

Although often treated as exogenous in optimal growth models, making population

growth an endogenous function allows us to analyse broader effects of economic activities on population. The issues of substitutability, innovation and capital accumulation are intertwined; allowing a model to address the effect of an endogenous technological change on substitutability between natural and man-made capital facilitates our analyses of sustainability issues. To address internalizing inter-generational externalities in resource use, incorporating property right changes

and institutional designs to this type of model is a useful exercise, but careful attention is needed for the consistency between such an arrangement and the mathematical representation of the depicted economy. Finally, although the common criticism regarding convenient mathematical assumptions applies to the existing BT-type models, the use of computer simulation can relax such assumptions, to better represent the intended relationships between the relevant variables.