Last updated: April 2016
Veggie vs Meat
The greenhouse gas emissions of food products is a big deal – agriculture accounts for about a third of world greenhouse gas emissions.
As a rule of thumb, the production of meat from plants is inherently inefficient. Each time you go up a level in the food chain you lose energy. For example, in the case of beef, which is substantially grass-fed, about 50g of soya goes into creating a 100g beef burger.
Red meat is also plagued by other climate issues, as it is the source of so much methane and nitrous oxide, both far stronger greenhouse gases than carbon dioxide.
(Please note, it is only animals that eat grass or other cellulose-based food that produce significant amounts of methane in their flatulence and burps. Human flatulence is nearly all nitrogen).
However, exactly how bad you think meat is for the climate depends on many things, not only how it is produced, but how you divide up responsibility for things like deforestation.
It is hard to find figures specifically on veggie burgers, but the relative figures for meat, Quorn and soya-based meat substitutes in general are given in the graphic below.
Although there are wide ranges in the figures (ranges shown under the graphic), for simplicity the graphic only shows the upper limits. The overall picture that emerges, unsurprisingly, is that veggie is generally better, and red meat is the super villain.
Out of the veggie options, soya generally seems to beat Quorn on greenhouse gas emissions. Quorn is the winner on land use though, which is to be expected given that it is not an agricultural product but is largely made from an industrial process (fermentation).
Yet as stated above, all of these figures are apt to change enormously depending on how things are produced and, if grown badly, soya may start to look a lot less virtuous compared to Quorn. One calculation suggested that the greenhouse gas impact of soya beans could vary from 0.1 kg CO2eq/kg if it was produced sustainably, to 16.5 kg CO2eq/kg, if it was produced on deforested land in the Amazon.