The carbon opportunity cost of livestock
This paper finds that a global shift to vegan diets by 2050 could allow sequestration of 332–547 GtCO2 - equivalent to or greater than the remaining emissions budget for having a 66% of limiting global warming to 1.5 °C. Meat reductions in line with the EAT-Lancet Commission’s recommendations could also lead to significant carbon sequestration.
The figure below shows changes in terrestrial (land-based) carbon in the case of business-as-usual following current economic trends, a 70% meat reduction or a global shift to vegan diets.
Image: Figure 3, Hayak et al. Cumulative changes in terrestrial carbon from three dietary scenarios in 2050: BAU (business as usual), ELC (70% meat reduction globally relative to BAU, in line with the recommendations of the EAT-Lancet Commission) and VGN (vegan - no animal-sourced foods).
The “carbon opportunity cost” of livestock production refers to the carbon sequestration that could happen if the land were not being used for livestock. This sequestration could happen through restoration of native ecosystems, including forests. The paper also notes that in areas of native grassland, vegetation can be partially restored by better management of grazing rather than by removing livestock altogether, but that trade-offs exist with other emissions (e.g. methane) from livestock. The dietary change scenarios in the paper assume that livestock is removed from pasture rather than managed differently.
The paper stresses that while carbon sequestration made possible by dietary change could contribute significantly to emissions reduction targets, ceasing fossil fuel use is also necessary for mitigating climate change.
The paper also points out that significant changes in agricultural production will have socioeconomic implications, but that climate change would also have significant impacts. It suggests that harmful impacts could be minimised by directing ecosystem restoration measures towards the areas of highest potential carbon storage. The dark green areas in the figure below correspond to areas offering the greatest potential increase in carbon storage in present-day animal feed croplands and pastures.
Image: Figure 1, Hayek et al. Distribution of carbon in potential vegetation in areas of present-day animal feed croplands and pastures combined for each 5 arcmin grid cell. Colour corresponds to the product of land area presently under cultivation multiplied by the potential vegetation carbon density, minus the quantity presently stored in agricultural vegetation.
Extensive land uses to meet dietary preferences incur a ‘carbon opportunity cost’ given the potential for carbon sequestration through ecosystem restoration. Here we map the magnitude of this opportunity, finding that shifts in global food production to plant-based diets by 2050 could lead to sequestration of 332–547 GtCO2, equivalent to 99–163% of the CO2 emissions budget consistent with a 66% chance of limiting warming to 1.5 °C.
Hayek, M.N., Harwatt, H., Ripple, W.J. and Mueller, N.D., 2020. The carbon opportunity cost of animal-sourced food production on land. Nature Sustainability, pp.1-4.
While some of the food system challenges facing humanity are local, in an interconnected world, adopting a global perspective is essential. Many environmental issues, such as climate change, need supranational commitments and action to be addressed effectively. Due to ever increasing global trade flows, prices of commodities are connected through space; a drought in Romania may thus increase the price of wheat in Zimbabwe.