Changing food consumption patterns and associated greenhouse gas (GHG) emissions have been a matter of scientific debate for decades. In a study by the Potsdam Institute for Climate Impact Research and the University of Potsdam Department of Geo- and Environmental Sciences , researchers undertook to assess the potential for climate change mitigation through optimal management and dietary changes in light of the agricultural sector’s role as one of the world’s major GHG emitters. Current agricultural practices are resource intensive, requiring fuel and fertilizer as well as significant water use (agricultural accounts for approximately 70% of global water withdrawal). In terms of GHG emissions, the study indicates that agriculture contributes between 10% to 14% to the total anthropogenic GHG emissions. The study also projected emissions and examined dietary patterns and their changes globally on a per country basis between 1961 and 2007.
Global population growth and poverty reduction are driving changes in food consumption both in terms of total amount and composition. Lifestyle-related changes in diet are also driving increases in food demand. A dietary shift towards a reduction in meat consumption has the potential to significantly decrease GHG emissions, but current trends are heading in the opposite direction. While an increase in the consumption of animal products, vegetable oils and sugar sweeteners has occurred primarily in developed countries over the past few decades, a westernization of diets has also been occurring in developing countries. However, animal protein, animal fat and vegetable oil intake remains significantly higher in developed countries as compared to developing countries.
In order to better understand diet related emissions, researchers identified typical dietary patterns of food consumption and composition per country for the period from 1961-2007. Detailed analyses show that food consumption patterns are moving from low to higher calorie diets, which is consistent with an overall trend of improvements to long-term nutrition. While low calorie diets are decreasing worldwide, there is a change in parallel diet composition as well. In particular, there is a discernible shift towards more balanced diets in developing countries and the move towards more meat-rich diets in developed countries is characteristic of this trend. As a result, environmental impacts in terms of fossil fuel requirements and total GHG emissions generally increased as diets become more calorie rich. Low calorie diets, which are mainly observable in developing countries, show a similar emissions burden as moderate and high calorie diets. This can be explained by a less efficient calorie production per unit of GHG emissions in developing countries. Very high calorie diets are common in the developed world and exhibit high total per capita emissions of 3.7–6.1 kg carbon dioxide equivalent (CO2e) per day due to high carbon intensity and high intake of animal products. In case of unconstrained demographic growth and changing dietary patterns, the projected emissions from agriculture will approach 20 Gt CO2e per year by 2050, which represents a 40% increase in agriculture-related GHG emissions compared to 2005 levels. This highlights the tremendous potential the food sector can play with respect to helping us achieve climate protection goals, particularly with the introduction of less energy intensive agricultural practices. The study suggests that optimized management of agriculture may contribute to emission reductions of up to 7 Gt CO2e per year in 2050. The authors also highlight the importance of the livestock sector for diet-related GHG emissions; emissions from this sector are increasing rapidly according to their estimates and approximately 14 Gt CO2e per year by 2050 will be related to the consumption of animal products. The authors conclude by saying that agricultural intensification should focus on an optimization of emission intensities, which keeping other environmental stresses and anthropogenic inputs as low as possible. Or as Michael Pollan, author of the Omnivore’s Dillema, says: “Eat food, not too much, mostly plants.”