In this article co-written by FCRN member Erasmus zu Ermgassen, the authors use what they call a holistic approach (described below) to estimate the GHG emissions savings from preventing UK household food waste. In particular, they include the consideration of a potential rebound effect: the GHG emissions that result from money saved (because of reduced food waste) being spent elsewhere.
In this article co-written by FCRN member Erasmus zu Ermgassen, the authors use what they call a holistic approach (described below) to estimate the GHG emissions savings from preventing UK household food waste. In particular, they include the consideration of a potential rebound effect: the GHG emissions that result from money saved (because of reduced food waste) being spent elsewhere. They find that this effect may reduce GHG savings by 23% to 59%. Still, the reductions are 5-12 times larger than the greenhouse gas saving if all food waste were to be used in bioenergy production.
The authors examined three scenarios based on WRAP (Waste and Resources Action Programme) estimates of the amount of UK waste that is avoidable (60%) and the additional waste that has the potential to be avoided (a further 23%) and compared this to a scenario in which wasted food is processed in an anaerobic digestion plant (the most common food waste treatment in the UK).
The authors note some key differences between their approach and more conventional LCA approaches to estimating GHG emissions associated with food waste. They call their approach holistic because in addition to conventional approaches to the same research question - life-cycle-assessment (LCA) studies - they use several other methods. They combine an LCA with a multi-regional environmentally extended input-output analysis. In this way they assess the GHG emissions across the global food supply chain for products consumed in the UK which allows the authors to consider imports and rebound effects; something that has not been done previously by others. They also use an econometric-based marginal expenditure model to estimate the size of the rebound effect.
The study finds the GHG emissions savings from preventing UK household food waste could be 706-896 kg CO2 equivalent per ton of food wasted. This includes their estimation of the rebound effect of up to 59% (See figure below). As a result, these emissions are relatively lower than others reported in the literature. Further, most of the estimated GHG reductions occur thanks to avoided food production overseas, while only 22% of estimated GHG savings occur within UK borders.
In order to avoid the rebound effect, the authors state that this effect must explicitly be considered by policy makers if GHG reductions are to be effectively achieved.
The environmental evaluation of food waste prevention is considered a challenging task due to the globalised nature of the food supply chain and the limitations of existing evaluation tools. The most significant of these is the rebound effect: the associated environmental burdens of substitutive consumption that arises as a result of economic savings made from food waste prevention. This study introduces a holistic approach to addressing these challenges, with a focus on greenhouse gas (GHG) emissions from household food waste in the UK. It uses a hybrid life-cycle assessment model coupled with a highly detailed multi-regional environmentally extended input output analysis to capture environmental impacts across the global food supply chain. The study also takes into consideration the rebound effect, which was modelled using a linear specification of an almost ideal demand system. The study finds that food waste prevention could lead to substantial reductions in GHG emissions in the order of 706–896 kg CO2-eq. per tonne of food waste, with most of these savings (78%) occurring as a result of avoided food production overseas. The rebound effect may however reduce such GHG savings by up to 60%. These findings provide a deeper insight into our understanding of the environmental impacts of food waste prevention: the study demonstrates the need to adopt a holistic approach when developing food waste prevention policies in order to mitigate the rebound effect and highlight the importance of increasing efficiency across the global food supply chain, particularly in developing countries.
Salemdeeb, R., Vivanco, D. F., Al-Tabbaa, A., & zu Ermgassen, E. K. (2016). A holistic approach to the environmental evaluation of food waste prevention. Waste Management.
Read the full article here (paywall).