Carbon footprints and land use of conventional and organic diets in Germany
Graphical abstract
Introduction
To support global food production, 70% of the world's grasslands, 50% of the savannas, 45% of deciduous temperate forests, and 27% of tropical forests have been cleared or converted to agriculture since pre-industrial times (Foley et al., 2011). As a consequence, biodiversity and ecosystem services have been severely damaged (MEA, 2005). At present, global food production causes more than 25% of global anthropogenic greenhouse gas (GHG) emissions (Edenhofer et al., 2014) and uses around one-third of the global ice-free land area (Foley et al., 2011). In order to meet the targets of the 2015 Paris Agreement, GHG emissions need to be drastically reduced, not only from fossil fuels, but also, most likely, from agriculture (Bryngelsson et al., 2016). Also, in order to reduce biodiversity loss and protect ecosystem services, land saving measures are needed (Foley et al., 2011).
Organic agriculture is often considered more environmentally friendly than conventional agriculture, since chemical pesticides and synthetic fertilizers are not used. Germany is one of the most important and fast-growing markets for organic food in Europe (Schaack, 2016). In a recent survey, 8% of German consumers (5% of men and 12% of women) declared to buy the largest share of their food in organic supermarkets (BMEL, 2016a). The per-capita expenditure on organic food in Germany is also well above the EU-28 average (Statista, 2015), and the German “Ökobarometer” (eco barometer) suggests that the frequency and intensity of organic food consumption increased in the last decade (BMEL, 2016b). Whereas 17% of the German population declared to often buy organic food in 2008 (BMEL, 2008), this proportion rose to 24% in 2016 (BMEL, 2016b).
Life cycle assessment (LCA) is a method commonly used for quantifying the environmental impacts of food products throughout their life cycle (JRC, 2010). LCA studies show that animal-based food products generally have larger carbon footprints than plant-based food products, since they are less efficient at transforming energy and nutrients to edible products (Westhoek et al., 2011). LCA studies also show that food products from ruminants (e.g., beef, lamb, and cheese) have larger carbon footprints than other animal-based food products, due to lower feed-conversion efficiency of ruminants and emissions of methane from enteric fermentation (Gerber et al., 2013). Feed-conversion efficiencies largely influence both GHG emissions and land use demand. Therefore, land use associated with food products show similar patterns as carbon footprints (Nijdam et al., 2012).
Most LCA studies quantify environmental impacts of individual food products, but people eat whole diets consisting of different food products depending on cultural, demographic, and socio-economic factors. A diet perspective enables simultaneous consideration of social, nutritional, and environmental aspects. Carbon footprints and/or land use have previously been quantified for conventional “average national” diets in the Netherlands (Temme et al., 2014), France (Vieux et al., 2012), the United Kingdom (Berners-Lee et al., 2012), Denmark (Saxe et al., 2013), Ireland (Hyland et al., 2016), and Europe as a whole (Tukker et al., 2011), using different methods. The environmental impacts of specific diets, such as vegan and vegetarian diets, have also been assessed, see, e.g., Hallström et al. (2015) and van Dooren et al. (2014).
In Germany, the Max Rubner-Institut carried out the second German National Nutrition Survey (NVS II) from 2005 to 2007, with the objective to map food consumption and nutritional behavior of German citizens ages 14 to 80 (Heuer et al., 2015). Specifically, food consumption of different population groups were described, including those consumers who do not buy organic food (referred to here as conventional consumers), as well as those who buy a high share of organic food (referred to here as organic consumers). The data from the NVS II have been used to describe the food consumption of adults and specific population groups in Germany (Heuer et al., 2015); assess the environmental impacts of conventional diets and gender-related differences (Meier and Christen, 2012), and the environmental impacts of lacto-ovo vegetarian and vegan diets, as well as diets that follow dietary recommendations (Meier and Christen, 2013a).
However, the carbon footprints and land use of an organic diet, and how these compare to a conventional diet, have not yet been quantified. Yet, some studies, e.g., Krarup et al. (2008) and Knudsen et al. (2011), suggest that people who consume mostly organic food also eat less carbon intensive and land-demanding food products, e.g., meat, than the average consumer. Hoffmann and Spiller (2010) found that consumers with preference for organic food are also more likely to be vegetarians, but the diet-related environmental impacts were not quantified. Baroni et al. (2006) found that Italian consumers eating organic food have lower diet-related carbon footprints but higher land use, compared to consumers eating conventionally produced food. The assessed diets were however only hypothetical, planned by a dietician.
This study aims to assess and compare the carbon footprints and land use of conventional and organic diets in Germany, for three consumer categories: men, women and their combined unweighted average. To our knowledge, this is the first study that assesses carbon footprints and land use of organic diets using consumer reported food consumption data. Most studies on organic eating habits have so far focused on the reasons or motives behind consumption, without analyzing actual food intake or the associated environmental impacts (Bravo et al., 2013). Germany is a particularly interesting study object given the importance and scale of organic food consumption in the country.
Section snippets
Material and methods
In short, carbon footprints and land use of conventional and organic diets in Germany were calculated by combining food consumption data for men and for women from the NVS II, with carbon footprint and land-use data primarily from LCA studies of conventional and organic food products. Land use of organic plant-based food products was assessed using land use of conventional plant-based food products as a baseline, and multiplying with crop-specific yield-correction factors accounting for the
Results
The results concerning food supply, carbon footprints, and land use of conventional and organic diets are presented here for the six consumer groups defined in Table 1. For this presentation, the 25 food categories used in the analysis are aggregated in 16 categories, see Chapter S13 in the Supplementary Material. For example, pomaceous fruits, stone fruits, citrus fruits, berries, nuts and seeds, and other fruits are aggregated and labeled “fruits”. Given that the results are associated with
Discussion
Carbon footprints and land use of conventional and organic diets in Germany were calculated for men, women, and their combined unweighted average, by combining food consumption data from the NVS II, with carbon footprint and land-use data from LCA studies of conventional and organic food products. Here, the results for food supply (Section 4.1), carbon footprints (Section 4.2) and land use (Section 4.3) are discussed, as well as how diet-related impacts can be reduced (Section 4.4) and the
Conclusions and recommendations
Food consumption data from the NVS II were combined with carbon footprint and land-use data from LCA studies of conventional and organic food products, to calculate carbon footprints and land use associated with organic and conventional diets in Germany. The calculations were made for the (unweighted) average consumer as well as for men and women separately. The average conventional diet contains 45% more meat than the average organic diet, which in turn contains 40% more vegetables, fruits,
Acknowledgements
Valuable input from several experts is gratefully acknowledged: Dr Anna Flysjö at Arla Foods, Britta Florén at SP Technical Research Institute of Sweden, and Camilla Sjörs at Karolinska Institutet. A special thanks to Dr Toni Meier at Martin-Luther Universität Halle Wittenberg, and to two anonymous reviewers for valuable comments. Financial support from the German Federal Ministry of Food, Agriculture, and Consumer Protection to the NVS II survey is gratefully acknowledged.
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