Switching from animal to plant-based foods cuts GHG emissions by 31%

Aim

The study aimed to evaluate the global environmental impact of replacing commonly consumed animal-sourced foods (ASF) with plant-based alternatives (PBA) by 2050.(1)

Method

The environmental impact of current ASF intakes and various dietary substitution scenarios between 2020 to 2050 were assessed.

The dietary scenarios

Reference diet (REF): current and projected eating patterns and preferences based on country specific datasets. This formed the baseline values for comparisons with the various substitution dietary scenarios.

Substitution dietary scenarios

ASF for substitution: pork, chicken, beef and milk were identified as the most commonly consumed ASF and thus the focus of the substitution with novel plant-based alternatives.

Recipes substituting ASF with PBA

• were matched for macro and micronutrient composition (including protein)

• used realistic ingredients that could be produced at the levels needed for the shift on a global basis by 2050

Different substitution scenarios

To assess all potential environmental outcomes, the authors investigated various scenarios:

• A global shift vs the 13 largest ASF consuming global regions

• The impact of substituting each of the ASF individually vs all ASF at once

• Starting with the REF diet, incremental substitution of 10%, 25%, 50% and 90% ASF with PBA between 2020 and 2050

• Sourcing of novel ingredients locally vs globally (greater degree of importation)

• Efficient vs inefficient utilisation of by-products from the production of the novel plant-based alternatives

Assessing the environmental impact

All dietary scenarios were assessed for their environmental impact using the Global Biosphere Management Model (GLOBIOM*).

Key findings

Global food system impact

REF scenario: continuing with ‘business as usual’, food demand is projected to grow globally between 2020 and 2050 and particularly ASF with a 38% and 24% increase demand projected for chicken and milk respectively. As a consequence, there will be an increased demand for land and crop production to accommodate the increase requirements for animal feed. By 2050, the environmental burden would markedly increase (see table 1), with increases in fertilizer use, water consumption, and GHG emissions. The need to extend agricultural area would lead to a decrease in forest area and consequently a further loss of biodiversity and carbon sink capacity.

Plant-based substitution scenarios

In the alternative scenarios, a gradual substitution of ASF with PBA between 2020 and 2050 would result in a decreased demand for ASF demand and thus a decrease in land use for crop production compared to the REF scenario.

A global 50% substitution of ASF with PBA by 2050 could result in a significant reductions across multiple environmental factors.

In the 50% substitution scenario which yielded the best results, the environmental impacts of food production would decline with the reduction of agricultural land use leading to a 31% decrease of GHGE in 2050.

Table 1. Environmental impact by 2050 of continuing with current eating habits or substituting 50% of animal-sourced food (ASF) with plant-based alternatives (PBA)

Substitutions of ASF beyond 50% yielded no further decline in deforestation or land use GHG emissions.

If unused livestock and feed land were restored through reforestation, this would further improve the environmental impact of substitution through an increase in biodiversity and carbon sequestration and thus, further decrease in GHG emissions.

The environmental impact of substitution varies regionally.

The 50% substitution scenario yielded encouraging results globally. However, its environmental impact was unequally distributed amongst regions. Namely, the substitution in China would lead to an important decrease in agricultural non-CO2 GHG emissions such as CH4 and N2O and a decrease in water and fertilizer use while in Sub-Saharan Africa and South America, land restoration would lead to a CO2 emission decrease through carbon sequestration. This is likely because the regional variations in population size and diet results in high variations in ASF type and demand amongst regions.

Sourcing PBA locally or from the global market (imports) had little influence on the environmental impact.

Conclusions

• A 50% substitution of ASF with PBA by 2050 represents a realistic and efficient scenario that would greatly decrease the environmental burden across multiple factors: 31% reduction in GHG emissions, nitrogen inputs would be halved and around a tenth of land and water use would be reduced by 12% and 10% respectively

• Land restoration policies will be crucial to maximise the beneficial impacts of the substitution on carbon sequestration and biodiversity through reforestation.

• In various countries, ASF play a major cultural and economic role, which also raises the issue of the socioeconomic impact of ASF substitutions on farmers livelihood, food safety and cultural acceptability, and the need to support the farmers in this transition.

*GLOBIOM is an internationally accredited economic-based computer model that can project future scenarios of how food production will impact on the environment taking into consideration multiple factors including land-use and land-use change, agriculture practices, resource use, carbon footprint including estimates of carbon sink and biodiversity restoration.

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