A study carried out by Professor Patrick Brown of Stanford University and Professor Michael Eisen of the University of California, Berkeley modelled the impact of a global end to livestock farming. The study demonstrates that ending animal agriculture and planting trees on the empty fields is our best and most immediate chance to turn back the clock on climate change.
Animal agriculture contributes significantly to global warming through ongoing emissions of the potent greenhouse gases methane and nitrous oxide, and displacement of biomass carbon (plants) on the land used to support livestock.
This research quantifies the full “climate opportunity cost” of current global livestock production, by modelling the combined, longterm effects of emission reductions and biomass recovery that would be unlocked by a phaseout of animal agriculture.
Although there are many uncertainties in the estimates, the assumption that “business as usual” means animal agriculture will continue at current levels was highly conservative, as rising incomes are driving ongoing growth in global animal product consumption. It is estimated that global demand for animal based foods will increase by nearly 70% by 2050. For example, extending the current diet of wealthy industrialised countries (OECD) to the current global population would require an additional 35 million km to support livestock production—an area roughly equal to the combined area of Africa and Australia. (this is the equivalent to all of the remaining land area of forested and unforested ecosystems with minimal human use as shown by the IPCC below).
While such an expansion may seem implausible, even partial destruction of Earth’s critical remaining native ecosystems would have catastrophic impacts not just on the climate, but on global biodiversity and human health.
The research shows that, even in the absence of any other emission reductions, persistent drops in atmospheric methane and nitrous oxide levels, and slower carbon dioxide accumulation, a phaseout of livestock production, through the end of the century, would:
- freeze increases in the warming potential of the atmosphere for 30 years.
- achieve half of the emission reductions necessary to limit warming to 2˚C.
- offset 68 percent of current anthropogenic CO2 emissions.
Replacing ruminants achieves over 90 percent of climate benefit of eliminating animal agriculture.
Discussion
Crucially eliminating the use of animals as food would produce substantial negative emissions of all three major GHGs, a necessity, as even the complete replacement of fossil fuel combustion in energy production and transportation will no longer be enough to prevent warming of 1.5˚C.
Although animal products currently provide, according to the most recent data from FAOSTAT, 18% of the calories, 40% of the protein and 45% of the fat in the human food supply, they are not necessary to feed the global population. Existing crops could replace the calories, protein and fat from animals with a vastly reduced land, water, GHG and biodiversity impact, requiring only minor adjustments to optimize nutrition.
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. It is likely that substantial global investment will be required to ensure that the people who currently make a living from animal agriculture do not suffer when it is reduced or replaced. And, while it is expected that the phaseout of animal agriculture would lead to global increases in food availability as edible crops cease to be diverted for animal feed, investment will also be required to prevent local food insecurity in regions where wide-scale access to a diverse and healthy plant-based diet is currently lacking and to ensure proper nutrition. But, in both cases, these investments must be compared to the economic and humanitarian disruptions of significant global warming.
It is important to emphasise that, as great as the potential climate impact of ending animal agriculture may be, even if it occurred, and even if all of the benefits we anticipate were realised, it would not be enough on its own to prevent catastrophic global warming. Rather, we have shown that global dietary change provides a powerful complement to the indispensable transition from fossil fuels to renewable energy systems.
The magnitude and rapidity of the potential effects should place the reduction or elimination of animal agriculture at the forefront of strategies for averting disastrous climate change.
You can read the full paper here.
