Climate change and dietary choices — how can emissions of greenhouse gases from food consumption be reduced?

Abstract

Results from an analysis of greenhouse gas emissions and energy consumption during the life-cycle of carrots, tomatoes, potatoes, pork, rice and dry peas consumed in Sweden are presented and discussed. The life-cycle is delineated to the part of the production chain prior to purchase by the consumer. The study shows that emissions, expressed in g CO 2 equivalents, are highest for pork and rice and lowest for potatoes, carrots and dry peas. The most important stages of emissions in the life-cycle are identified for each of the different food items. Crop farming is the most important stage for rice and tomatoes while rearing of animals is the most important stage for pork and storage is the most important stage for carrots. Comparison with an energy analysis shows that important stages in the life-cycle of food may be under-evaluated when energy only is accounted for. This may lead to a sub-optimisation of pollution control exemplified by the case of transportation. Also, it is shown that the choice of functional unit has a decisive influence on the outcome of the study. The recommendation is to compare whole meals, or diets with the same nutritional qualities. A comparison of four meals composed of the food items under analysis shows that a meal with tomatoes, rice and pork has nine times higher emissions than a meal made from potatoes, carrots and dry peas. Emissions of greenhouse gases from consumption patterns based on the food items analysed are compared with an assumed sustainable limit of greenhouse gas emissions. The conclusion is that current food consumption patterns in the developed countries exceed the level of sustainability by at least a factor of 4. Prospects for achieving sustainable food consumption patterns are questionable in view of current trends in food demand.