Quantifying the unquantifiable: simulation of displacement rates among textile fibers

Abstract Substitution can help avoid environmental impacts when preferring low impact technologies and feedstocks. The substitution benefit is typically assessed using life cycle assessment (LCA). However, LCA only quantifies the environmental impacts of product systems, while approaches from the field of economics are required to quantify the displacement rate (DR)—the market response that a change in the production of one product has on the production of alternative products. Substitution only occurs in comparison to a counterfactual and therefore remains essentially unobservable. This study introduces a novel approach with the aim of radically reducing the uncertainty of DR estimates. System dynamics modeling is adopted allowing the DRs to be quantified by recreating alternative histories in addition to future shocks. The approach is applied to the global textile fiber market. While the backward- and forward-looking scenarios yielded similar results, the former were essential in relieving the uncertainty associated with the latter. The results show that substitution occurs mainly between regenerated cellulosic fibers (RCFs) and cotton, whereas RCFs and cotton are mostly unaffected by changes in the production and price of synthetic fibers. Overall, a one-unit increase in the production of one fiber leads to a 0–32% reduction in the production of alternative fibers. The rest of the increase in supply merely adds to overall consumption, thus reversing the substitution benefit from net avoided to net caused impacts in most impact categories. Alternative policy and strategy pathways are therefore required to address the effects of overconsumption of textiles fueled by fast fashion.