Erasmus K.H.J. zu Ermgassen

How can higher-yield farming help to spare nature?

Mechanisms to link yield increases with conservation Expansion of land area used for agriculture is a leading cause of biodiversity loss and greenhouse gas emissions, particularly in the tropics. One potential way to reduce these impacts is to increase food production per unit area (yield) on existing farmland, so as to minimize farmland area and to spare land for habitat conservation or restoration. There is now widespread evidence that such a strategy could benefit a large proportion of wild species, provided that spared land is conserved as natural habitat (1). However, the scope for yield growth to spare land by lowering food prices and, hence, incentives for clearance (“passive” land sparing) can be undermined if lower prices stimulate demand and if higher yields raise profits, encouraging agricultural expansion and increasing the opportunity cost of conservation (2, 3). We offer a first description of four categories of “active” land-sparing mechanisms that could overcome these rebound effects by linking yield increases with habitat protection or restoration (table S1). The effectiveness, limitations, and potential for unintended consequences of these mechanisms have yet to be systematically tested, but in each case, we describe real-world interventions that illustrate how intentional links between yield increases and land sparing might be developed.

Environmental and health impacts of using food waste as animal feed: a comparative analysis of food waste management options

The disposal of food waste is a large environmental problem. In the United Kingdom (UK), approximately 15 million tonnes of food are wasted each year, mostly disposed of in landfill, via composting, or anaerobic digestion (AD). European Union (EU) guidelines state that food waste should preferentially be used as animal feed though for most food waste this practice is currently illegal, because of disease control concerns. Interest in the potential diversion of food waste for animal feed is however growing, with a number of East Asian states offering working examples of safe food waste recycling – based on tight regulation and rendering food waste safe through heat treatment. This study investigates the potential benefits of diverting food waste for pig feed in the UK. A hybrid, consequential life cycle assessment (LCA) was conducted to compare the environmental and health impacts of four technologies for food waste processing: two technologies of South Korean style-animal feed production (as a wet pig feed and a dry pig feed) were compared with two widespread UK disposal technologies: AD and composting. Results of 14 mid-point impact categories show that the processing of food waste as a wet pig feed and a dry pig feed have the best and second-best scores, respectively, for 13/14 and 12/14 environmental and health impacts. The low impact of food waste feed stems in large part from its substitution of conventional feed, the production of which has substantial environmental and health impacts. While the re-legalisation of the use of food waste as pig feed could offer environmental and public health benefits, this will require support from policy makers, the public, and the pig industry, as well as investment in separated food waste collection which currently occurs in only a minority of regions.

A holistic approach to the environmental evaluation of food waste prevention

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 706-896kg 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.

Reduce, relegalize, and recycle food waste

J. Aschemann-Witzel (“Waste not, want not, emit less,” Perspectives, 22 April, p. [408][1]) describes the challenges and benefits of reducing food waste, but does not discuss what to do with the food waste that remains. Because not all food waste is avoidable, it is critically important to pair

Support amongst UK pig farmers and agricultural stakeholders for the use of food losses in animal feed

While food losses (foods which were intended for human consumption, but which ultimately are not directly eaten by people) have been included in animal feed for millennia, the practice is all but banned in the European Union. Amid recent calls to promote a circular economy, we conducted a survey of pig farmers (n = 82) and other agricultural stakeholders (n = 81) at a UK agricultural trade fair on their attitudes toward the use of food losses in pig feed, and the potential relegalisation of swill (the use of cooked food losses as feed). While most respondents found the use of feeds containing animal by-products or with the potential for intra-species recycling (i.e. pigs eating pork products) to be less acceptable than feeds without, we found strong support (>75%) for the relegalisation of swill among both pig farmers and other stakeholders. We fit multi-hierarchical Bayesian models to understand people’s position on the relegalisation of swill, finding that respondents who were concerned about disease control and the perception of the pork industry supported relegalisation less, while people who were concerned with farm financial performance and efficiency or who thought that swill would benefit the environment and reduce trade-deficits, were more supportive. Our results provide a baseline estimate of support amongst the large-scale pig industry for the relegalisation of swill, and suggest that proponents for its relegalisation must address concerns about disease control and the consumer acceptance of swill-fed pork.

The environmental costs and benefits of high-yield farming

How we manage farming and food systems to meet rising demand is pivotal to the future of biodiversity. Extensive field data suggest that impacts on wild populations would be greatly reduced through boosting yields on existing farmland so as to spare remaining natural habitats. High-yield farming raises other concerns because expressed per unit area it can generate high levels of externalities such as greenhouse gas emissions and nutrient losses. However, such metrics underestimate the overall impacts of lower-yield systems. Here we develop a framework that instead compares externality and land costs per unit production. We apply this framework to diverse data sets that describe the externalities of four major farm sectors and reveal that, rather than involving trade-offs, the externality and land costs of alternative production systems can covary positively: per unit production, land-efficient systems often produce lower externalities. For greenhouse gas emissions, these associations become more strongly positive once forgone sequestration is included. Our conclusions are limited: remarkably few studies report externalities alongside yields; many important externalities and farming systems are inadequately measured; and realizing the environmental benefits of high-yield systems typically requires additional measures to limit farmland expansion. Nevertheless, our results suggest that trade-offs among key cost metrics are not as ubiquitous as sometimes perceived.High-yield farming systems have the potential to spare non-farmed land for other uses (such as nature conservation), but raise concerns about their other environmental impacts (such as greenhouse gas emissions and soil erosion). This study argues such impacts should be measured per unit of production and shows that viewed this way, some land-efficient systems have less impact than lower-yielding alternatives.

Agricultural Productivity and Forest Conservation: Evidence from the Brazilian Amazon

A mix of public policy and market interventions in the mid-2000s led to historic reductions in deforestation in the Brazilian Amazon. The collateral impact of these forest conservation policies on agricultural production is still poorly understood, though evidence is sorely needed given the economic importance of agriculture in Brazil and many other forest-rich countries. We construct a ten-year panel dataset for agriculture and deforestation in the Brazilian Amazon (2004-2014), and use two complementary difference-in-difference strategies to estimate the causal effect of one of Brazil’s flagship anti-deforestation strategies, the priority list (Municípios Prioritários), on agricultural production and productivity in three sectors: beef, dairy, and crop production. We find no evidence for trade-offs between agriculture and forest conservation. Rather, reductions in deforestation in priority municipalities were paired with increases in cattle production and productivity (cattle/hectare), consistent with a model where policy-induced decreases in the value of clearing new land cause credit-constrained farmers to shift investments from deforestation to capital investments in farming. The policy had no effect on dairy or crop production. Our results suggest that in regions with large yield gaps and where technologies for increasing yields are readily available, efforts to constrain agricultural expansion through improved forest conservation policies may induce intensification.

Research data supporting “A holistic approach to the environmental evaluation of food waste prevention”

The microeconomic rebound effect consists of a direct and indirect effect: the direct effect is related to the additional demand for the product that has been subject to an efficiency improvement (i.e. additional demand for some categories of food, where the efficiency improvement is an increase in the ratio between the food purchased and consumed), whereas the indirect effect refers to the additional demand in all other consumption categories. Tables attached below includes multipliers that could be used to determine the rebound effect associated with UK household savings in the UK. Data provided below is presented in two formats: Exiobase and COICOP. The readership is advised to refer to the paper for more details about the methodology utilised to generate these multipliers.