Food production and consumption cause approximately one-third of total greenhouse gas emissions1–3, and therefore delivering food security challenges not only the capacity of our agricultural system, but also its environmental sustainability4–7. Knowing where and at what level environmental impacts occur within particular food supply chains is necessary if farmers, agri-food industries and consumers are to share responsibility to mitigate these impacts7,8. Here we present an analysis of a complete supply chain for a staple of the global diet, a loaf of bread. We obtained primary data for all the processes involved in the farming, production and transport systems that lead to the manufacture of a particular brand of 800 g loaf. The data were analysed using an advanced life cycle assessment (LCA) tool9, yielding metrics of environmental impact, including greenhouse gas emissions. We show that more than half of the environmental impact of producing the loaf of bread arises directly from wheat cultivation, with the use of ammonium nitrate fertilizer alone accounting for around 40%. These findings reveal the dependency of bread production on the unsustainable use of fertilizer and illustrate the detail needed if the actors in the supply chain are to assume shared responsibility for achieving sustainable food production.
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Garnett, T. Where are the best opportunities for reducing greenhouse gas emissions in the food system (including the food chain)? Food Policy 36, S23–S32 (2011).
Tubiello, F. N. et al. The contribution of agriculture, forestry and other land use activities to global warming, 1990–2012. Glob. Chang. Biol. 21, 2655–2660 (2015).
Vermeulen, S. J., Campbell, B. M. & Ingram, J. S. I. Climate change and food systems. Ann. Rev. Enviro. Resour. 37, 195–222 (2012).
Tilman, D. et al. Agricultural sustainability and intensive production practices. Nature 418, 671–677 (2002).
Godfray, H. J. C. et al. Food security: the challenge of feeding 9 billion people. Science 327, 812–818 (2010).
Foley, J. A. et al. Solutions for a cultivated planet. Nature 478, 337–342 (2011).
Horton, P., Koh, S. C. L. & Shi Guang, V. An integrated theoretical framework to enhance resource efficiency, sustainability and human health in agri-food systems. J. Cleaner Prod. 120, 164–169 (2016).
Lenzen, M., Murray, J., Sack, F. & Wiedmann, T. Shared producer and consumer responsibility—theory and practice. Ecol. Econ. 61, 27–42 (2007).
Koh, S. et al. Decarbonising product supply chains: design and development of an integrated evidence-based decision support system—the supply chain environmental analysis tool (SCEnAT). Int. J. Prod. Res. 51, 2092–2109 (2013).
World Population Prospects: The 2010 Revision, Highlights (Population Division of the Department of Economic and Social Affairs of the United Nations, 2010).
Tilman, D. & Clark, M. Global diets link environmental sustainability and human health. Nature 515, 518–522 (2014).
O'Rourke, D. The science of sustainable supply chains. Science 344, 1124–1127 (2014).
Hellweg, S. & Canals, L. M. Emerging approaches, challenges and opportunities in life cycle assessment. Science 344, 1109–1113 (2014).
Jenson, J. K. & Arlbjørn, J. S. Product carbon footprint of rye bread. J. Clean. Prod. 82, 45–57 (2014).
Kulak, M. et al. Life cycle assessment of bread from several alternative food networks in Europe. J. Clean. Prod. 90, 104–113 (2015).
Espinoza-Orias, N., Stichnothe, H. & Azapagie, A. The carbon footprint of bread. Int. J. Life Cycle Assess. 16, 351–365 (2011).
Andersson, K. & Ohlsson, T. Life cycle assessment of bread produced on different scales. Int. J. Life Cycle Assess. 4, 25–40 (1999).
Paustian, K. et al. Climate-smart soils. Nature 532, 49–57 (2016).
Grassini, P. & Cassman, K. G. High-yield maize with large net energy yield and small global warming intensity. Proc. Natl Acad. Sci. USA 109, 1074–1079 (2012).
Gan, Y. et al. Improving farming practices reduces the carbon footprint of spring wheat production. Nat. Commun. 5, 5012 (2014).
Zhang, X. et al. Managing nitrogen for sustainable development. Nature 528, 51–58 (2015).
Brentrup, F. & Palliere, C. Nitrogen use Efficiency as an Agro-Environmental Indicator (OECD, 2010); www.oecd.org/tad/sustainable-agriculture/44810433.pdf
Mueller, N. D. et al. Closing yield gaps through nutrient and water management. Nature 490, 254–257 (2012).
Jensen, E. S. et al. Legumes for mitigation of climate change and the provision of feedstock for biofuels and biorefineries. A review. Agron. Sustain. Dev. 32, 329–364 (2012).
Cameron, D. D. Arbuscular mycorrhizal fungi as (agro)ecosystem engineers. Plant Soil 333, 1–5 (2010).
Han, M. et al. The genetics of nitrogen use efficiency in crop plants. Annu. Rev. Genet. 49, 269–289 (2015).
Xu, G., Fan, X. & Miller, A. J. Plant nitrogen assimilation and use efficiency. Annu. Rev. Plant Biol. 63, 153–182 (2012).
Long, S. P., Marshall-Colon, A. & Zhu, X.-G. Meeting the global food demand of the future by engineering crop photosynthesis and yield potential. Cell 161, 56–66 (2015).
Mosleth, E. F. et al. A novel approach to identify genes that determine grain protein deviation in cereals. Plant Biotech. J. 13, 625–635 (2015).
Oldroyd, G. E. D. & Dixon, R. Biotechnological solutions to the nitrogen problem. Curr. Opin. Biotechnol. 26, 19–24 (2014).
Green Food Project Bread Subgroup Report (DEFRA, 2012); https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69572/pb13797-greenfoodproject-breadsubgroup.pdf
Davidson, E. A., Suddick, E., Rice, C. W. & Prokoby, L. S. More food, low pollution (Mo Fo Lo Po): a grand challenge for the 21st century. J. Environ. Qual. 44, 305–311 (2015).
Trudge, C. Six Steps Back to the Land: Why We Need Small Mixed Farms and Millions More Farmers (Green Books, 2016).
Weidema, B. P. et al. The Ecoinvent Database: Overview and Methodology, Data Quality Guideline for the Ecoinvent Database Version 3. (ecoinvent, 2013); www.ecoinvent.org
Guinée, J. B. et al. (eds) Handbook on Life Cycle Assessment. Operational Guide to the ISO Standards (Kluwer Academic Publishers, 2002).
Svanes, E., Vold, M. & Hanssen, O. J. Effect of different allocation methods on LCA results of products from wild-caught fish and on the use of such results. Int. J. Life Cycle Assess. 16, 512 (2011).
ISO 14040:2006 Environmental Management—Life Cycle Assessment—Principles and Framework (BSI, 2006).
ISO 14044:2006 Environmental Management—Life Cycle Assessment—Requirements and Guidelines (BSI, 2006).
Fujihara, S., Sasaki, H., Aoyagi, Y. & Sugahara, T. Nitrogen-to-protein conversion factors for some cereal products in Japan. J. Food Sci. 73, C204–C209 (2008).
Bouwman, A. F., Boumans, L. J. M. & Batjes, N. H. Modeling global annual N2O and NO emissions from fertilized fields. Glob. Biochem. Cycles 16, 1–9 (2002).
IPCC Guidelines for National Greenhouse Gas Inventories (IPCC, 2006).
Brentup, F. & Palliere, C. GHG emissions and energy efficiency in European nitrogen fertiliser production and use. Proc. Int. Fertiliser Soc. 639, 1–25 (2008).
We thank the Grantham Foundation for the Protection of the Environment for their generous support. L.G. was supported in part by Impact, Innovation and Knowledge Exchange (IIKE) funds from the University of Sheffield and pump priming funding from the P3 Centre. We also gratefully acknowledge the support of our commercial partners.
The authors declare no competing financial interests.
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Goucher, L., Bruce, R., Cameron, D. et al. The environmental impact of fertilizer embodied in a wheat-to-bread supply chain. Nature Plants 3, 17012 (2017). https://doi.org/10.1038/nplants.2017.12
Life cycle assessment of autochthonous varieties of wheat and artisanal bread production in Galicia, Spain
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