The FAO estimates that emissions from animal agriculture represent around 7.1 Gt CO2e per year, accounting for 14.5% of annual anthropogenic greenhouse gas (GHG) emissions.
If native biomass – made up of forest, grassland, and soil – were allowed to recover the 30% of the Earth’s land surface currently devoted to livestock production, recent research suggests 800 GT CO2e carbon could be fixed via photosynthesis.
Combining the phaseout of animal agriculture with native biomass recovery could mean big news for the planet’s current global warming trajectory, hypothesised Impossible Foods CEO Patrick Brown and UC Berkeley’s Michael Eisen, an advisor to Impossible Foods.
"Everybody knows that methane is a problem. Everybody knows that livestock contribute to global warming in some way," said Eisen. "But animal ag contributes to global warming in two ways: It contributes via emissions and contributes because that land would otherwise be holding carbon. Most analyses only look at one of those things."
In a new study published in PLOS Climate, the duo used a simple climate model to project how both these changes would impact the evolution of atmospheric GHG levels and warming for the rest of the century.
An opportunity to ‘sharply bend the trajectory of climate change’
Brown and Eisen found that a rapid phaseout of animal agriculture could achieve half of the emissions reductions needed to meet the Paris Agreement GHG targets. Further, findings suggested that eliminating animal agriculture has the potential to offset 68% of current anthropogenic CO2 emissions.
And focusing on specific food categories, the duo’s calculations suggested that replacing ruminants achieves over 90% of climate benefit of eliminating animal agriculture.
It should be noted that these findings are in the interest of both Brown and Eisen. As both are shareholders in meat alternative company Impossible Foods, both stand to benefit financially from a reduction in animal agriculture.
“Our work shows that ending animal agriculture has the unique potential to significantly reduce atmospheric levels of all three major greenhouse gases, which, because we have dithered in responding to the climate crisis, is now necessary to avert climate catastrophe,” said Eisen, who aside from his consultancy work at Impossible Foods, is also a Howard Hughes Medical Institute (HHMI) investigator at UC Berkeley.
The duo noted that a major reason for the large, long-term effect, is that its benefits accrue rapidly. A substantial fraction of the emissions impact of animal agriculture comes from methane and nitrous oxide, which decay far more rapidly than CO2.
“Eliminating animal agriculture would have a quicker and greater impact over the next 20 to 50 years, the critical window for avoiding climate catastrophe, and thus should be at the top of the list of potential climate solutions,” said Brown.
“There is an enormous, previously unrecognised opportunity to sharply bend the trajectory of climate change within a couple of decades, with multiple additional environmental and public health benefits, and minimal economic disruption.”
Is a 15-year phaseout, worldwide, realistic?
Eisen and Brown, both vegan, would happily see the animal agricultural system dismantled today. Instead the duo chose a more realistic scenario.
“A 15-year phaseout is not unrealistic – a lot of things can happen on that timeframe,” said Eisen.
"We went from having no cellphones to cellphones being ubiquitous in less time than that. It's not that we're saying we're going to get rid of animal ag in the next 15 years, though that's sort of the mission for Impossible Foods, but that is something we could do."
According to their findings, a 15-year phaseout would immediately eliminate about one-third of all methane emissions globally and two-thirds of all nitrous oxide emissions, contributing to a significant reduction of both in the atmosphere.
Of course, transitioning away from animal agriculture is no mean feat. Meat, dairy and eggs are a major component of global human diets and the raising of livestock is integral to rural economies worldwide, noted the study authors. It is estimated that more than a billion people make all, or part, of their living from animal agriculture.
“The economic and social impacts of a global transition to a plant-based diet would be acute in many regions and locales, a major obstacle to their adoption,” Eisen and Brown conceded.
Both believe it is likely global investment will be required to support those currently earning a living from animal agriculture during the transition, as well as to prevent local food insecurity in regions where wide-scale access to healthy plant-based diet is lacking.
“But, in both cases, these investments must be compared to the economic and humanitarian disruptions of significant global warming.”
Source: PLOS Climate
‘Rapid global phaseout of animal agriculture has the potential to stabilize greenhouse gas levels for 30 years and offset 68 percent of CO2 emissions this century’
Published 1 February 2022
Authors: Michael B. Eisen, Patrick O. Brown.