Alexander Peter, Brown Calum, Arneth Almut, Finnigan John, Moran Dominic, Rounsevell Mark D A
School of Geosciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK.
Land Economy and Environment Research Group, SRUC, West Mains Road, Edinburgh EH9 3JG, UK.
Agric Syst. 2017 May;153:190-200. doi: 10.1016/j.agsy.2017.01.014.
Losses at every stage in the food system influence the extent to which nutritional requirements of a growing global population can be sustainably met. Inefficiencies and losses in agricultural production and consumer behaviour all play a role. This paper aims to understand better the magnitude of different losses and to provide insights into how these influence overall food system efficiency. We take a systems view from primary production of agricultural biomass through to human food requirements and consumption. Quantities and losses over ten stages are calculated and compared in terms of dry mass, wet mass, protein and energy. The comparison reveals significant differences between these measurements, and the potential for wet mass figures used in previous studies to be misleading. The results suggest that due to cumulative losses, the proportion of global agricultural dry biomass consumed as food is just 6% (9.0% for energy and 7.6% for protein), and 24.8% of harvest biomass (31.9% for energy and 27.8% for protein). The highest rates of loss are associated with livestock production, although the largest absolute losses of biomass occur prior to harvest. Losses of harvested crops were also found to be substantial, with 44.0% of crop dry matter (36.9% of energy and 50.1% of protein) lost prior to human consumption. If human over-consumption, defined as food consumption in excess of nutritional requirements, is included as an additional inefficiency, 48.4% of harvested crops were found to be lost (53.2% of energy and 42.3% of protein). Over-eating was found to be at least as large a contributor to food system losses as consumer food waste. The findings suggest that influencing consumer behaviour, e.g. to eat less animal products, or to reduce per capita consumption closer to nutrient requirements, offer substantial potential to improve food security for the rising global population in a sustainable manner.
食品系统各个阶段的损耗会影响全球不断增长的人口的营养需求能否得到可持续满足。农业生产中的低效和损耗以及消费者行为都起到了一定作用。本文旨在更深入了解不同损耗的规模，并深入探讨这些损耗如何影响食品系统的整体效率。我们从农业生物质的初级生产一直到人类的食物需求和消费，采用系统视角进行研究。计算并比较了十个阶段的数量和损耗，涉及干物质、湿物质、蛋白质和能量。比较结果显示这些测量值之间存在显著差异，而且先前研究中使用的湿物质数据可能会产生误导。结果表明，由于累积损耗，作为食物被消费的全球农业干生物质比例仅为6%（能量为9.0%，蛋白质为7.6%），收获生物质的24.8%（能量为31.9%，蛋白质为27.8%）。损耗率最高的与畜牧生产相关，尽管生物质的最大绝对损耗发生在收获之前。研究还发现收获作物的损耗也很大，44.0%的作物干物质（能量为36.9%，蛋白质为50.1%）在人类消费之前就已损失。如果将人类过度消费（定义为超出营养需求的食物消费）视为额外的低效率因素，那么发现48.4%的收获作物被损耗（能量为53.2%，蛋白质为42.3%）。暴饮暴食被发现至少与消费者食物浪费一样是食品系统损耗的重要因素。研究结果表明，影响消费者行为，例如少吃动物产品，或使人均消费更接近营养需求，对于以可持续方式改善全球不断增长人口的粮食安全具有巨大潜力。
