If everyone became vegan and so ate only fruit and vegetables, then the reduction in greenhouse emissions for the whole of food consumption would be a mere 7%. The widespread adoption of vegetarianism would have even less impact, while organic food production actually leads to a net increase in greenhouse gas emissions. Those are the conclusions of a research paper published in the journal Progress in Industrial Ecology.

Helmi Risku-Norja and Sirpa Kurppa of MTT Agrifood Research Finland, working with Juha Helenius of the Department of Agricultural Sciences, University of Helsinki, have determined that the cultivation of soil for whatever purpose, whether growing crops or raising livestock is the primary source of greenhouse gas emissions in food production, not fertiliser production, animal husbandry, nor agricultural energy requirements.

The team explains that for current average food consumption, in Finland, emissions from soil represent 62% of the total emissions. Greenhouses gases released by cows and sheep account for 24%, and energy consumption and fertiliser manufacture about 8% each. The greenhouse emissions performance for extensive organic production is poor, they explain, despite this approach to farming being considered the "green" option, the lower efficiency requires the cultivation of greater areas of soil, which counteracts many of the benefits.

Reducing greenhouse gas emissions through food consumption would require large-scale changes among the entire population, the team points out. They suggest that rather than stressing the impact of an individual citizen's dietary choices, we should be paying more attention to social learning and to the notion of working towards food sustainability and security. In general, sustainable consumption might be possible by introducing services to substitute for material consumption. Although food itself cannot be substituted, a lot can be done at the household level to improve sustainability of food provisioning and reduce food wastage.

"There is a pressing need to design effective policy measures," says Risku-Norja. "Consumer information is important from the viewpoint of food and sustainability education, leading eventually to adopting more sustainable lifestyles in the coming generations," the team concludes.