Animal products are a large source of greenhouse gas emissions (Photo: Russel Chayne/Reuters)
They acknowledge this scenario would never happen but have carried out the analysis to illustrate just how effective giving up animal products is at curbing greenhouse gas emissions.
They projected that if everyone went vegan, 52 per cent of the emissions cut needed to limit warming to 2C would be achieved. That is still less than the current highly ambitious global target of 1.5°C.
“This study shows that a global transition away from the use of animals, especially cattle, to produce food has the potential to rapidly remove large amounts of carbon dioxide, methane and nitrous oxide from the atmosphere, representing a unique opportunity to achieve the negative emissions required to keep temperatures from exceeding 2C,” said Mike Eisen, of the University of California, Berkeley.
Like his co-author, Patrick Brown of Stanford University, he stands to gain financially from a switch to vegan products because of his involvement in Impossible Foods, a company developing plant-based alternatives to animal products.
However, the study has been peer-reviewed and published in the journal PLOS Climate.
Much of the reduction would come in the form of lower methane and nitrous oxide output, as well as less CO2 being emitted due to reduced deforestation. However, for this study, the researchers have translated the amounts of the various greenhouse gases into the equivalent of CO2.
The switch to plant-only animal substitutes would save the equivalent of 25 billion tonnes of CO2 a year, primarily by reducing methane emissions from livestock and by reducing deforestation for grazing and planting new trees on land freed up by the switch.
The switch from cattle farming would account for 71 per cent of the emissions reduction – 47 per cent through beef and 24 per cent through milk.
Professor Heiko Balzter of the University of Leicester, who was not involved in the study, said: “Eating less meat is good for the climate. Switching to an entirely plant-based diet is certain to have a hugely beneficial effect on stabilising the global climate.
“However, it is an extreme scenario that raises many questions as well. For example, what would happen to biodiversity if grazing was stopped entirely? How would people’s diets change – would everyone have access to a balanced supply of foodstuffs? And how would organic agriculture work without manure as fertiliser?”
Dr Jonathan Foot, Head of Environment at the Agriculture and Horticulture Development Board, a non-departmental UK government body said:
“The report is yet another flawed modelling study using scaled up global emissions – with oversimplified assumptions to draw unrealistic conclusions about the impact of removing livestock from food production.
“Failure to consider whether such a move would produce enough food for a growing global population, or the socioeconomic impact on developing countries is a grossly significant omission.
“Not to mention the impact on global soil health and nutrition, and our realistic ability to increase global crop lands, considering the effects of climate change such as increasing temperatures, floods, and drought.
“Livestock and crop production are intrinsically linked, removing one greatly impacts the productivity of the other. Regionality is key when assessing sustainability, as many areas of the globe are very well suited to livestock production, thanks to ideal temperatures, plentiful rain, and grass. The marriage between well managed grasslands and grazing livestock can and does provide highly sustainable food production, like what we see here in the UK.”