Replacing animal agriculture and shifting to a plant-based diet could drastically curb greenhouse gas emissions, according to new model

Date:
February 1, 2022
Source:
Stanford University
Summary:
Phasing out animal agriculture represents 'our best and most
immediate chance to reverse the trajectory of climate change,'
according to a new model developed by scientists.



FULL STORY ==========================================================================
The worldwide phase out of animal agriculture, combined with a global
switch to a plant-based diet, would effectively halt the increase of atmospheric greenhouse gases for 30 years and give humanity more time to
end its reliance on fossil fuels, according to a new study by scientists
from Stanford University and the University of California, Berkeley.


==========================================================================
"We wanted to answer a very simple question: What would be the impact
of a global phase-out of animal agriculture on atmospheric greenhouse
gases and their global-heating impact?" said Patrick Brown, a professor emeritus in the department of biochemistry at Stanford University. Brown co-authored the paper with Michael Eisen, a professor of genetics and development at UC Berkeley.

Based on the model, published in the open-access journal PLoS Climate,
phasing out animal agriculture over the next 15 years would have the
same effect as a 68 percent reduction of carbon dioxide (CO2) emissions
through the year 2100.

This would provide 52 percent of the net emission reductions necessary
to limit global warming to 2 degrees Celsius above preindustrial levels,
which scientists say is the minimum threshold required to avert disastrous climate change.

The changes would stem, the authors say, from the spontaneous decay of
the potent greenhouse gases methane and nitrous oxide, and the recovery
of biomass in natural ecosystems on the more than 80 percent of humanity's
land footprint currently devoted to livestock.

"Reducing or eliminating animal agriculture should be at the top of
the list of potential climate solutions," Brown said. "I'm hoping that
others, including entrepreneurs, scientists and global policymakers, will recognize that this is our best and most immediate chance to reverse the trajectory of climate change, and seize the opportunity." Brown is also
the founder and CEO of Impossible Foods, a company developing alternatives
to animals in food production. Eisen is an advisor to the company.

Both Brown and Eisen stand to benefit financially from the reduction of
animal agriculture.



========================================================================== Unlocking negative emissions Brown and Eisen are not the first to point
out that ongoing emissions from animal agriculture are contributing
to global warming. But what has not been recognized before, they say,
is the much more impactful "climate opportunity cost" -- the potential
to unlock negative emissions by eliminating livestock.

"As the methane and nitrous oxide emissions from livestock diminish, atmospheric levels of those potent greenhouse gases will actually drop dramatically within decades," Brown said. "And the CO2 that was released
into the atmosphere when forests and wild prairies were replaced by feed
crops and grazing lands can be converted back into biomass as livestock
are phased out and the forests and prairies recover." Brown and Eisen
used publicly available data on livestock production, livestock-linked emissions and biomass recovery potential on land currently used to support livestock to predict how the phaseout of all or parts of global animal agriculture production would alter net anthropogenic, or human-caused, emissions from 2019 levels. They then used a simple climate model to
project how these changes would impact the evolution of atmospheric
greenhouse gas levels and warming for the rest of the century.

They examined four dietary scenarios: an immediate replacement of all
animal agriculture with a plant-only diet; a more gradual and, the authors
say, more realistic, 15-year transition to a global plant-only diet; and versions of each where only beef was replaced with plant-only products.



==========================================================================
For each hypothetical scenario, the scientists assumed that
non-agricultural emissions would remain constant and that the land
formerly used for livestock production would be converted to grasslands, prairies, forests and the like that will absorb atmospheric CO2.

"The combined effect is both astoundingly large, and -- equally
important - - fast, with much of the benefit realized by 2050," Brown
said. "If animal agriculture were phased out over 15 years and all other greenhouse-gas emissions were to continue unabated, the phase-out would
create a 30-year pause in net greenhouse gas emissions and offset almost
70 percent of the heating effect of those emissions through the end of
the century." While the complete phase out of animal-based agriculture
was projected to have the largest impact, 90 percent of the emission
reductions could be achieved by only replacing ruminants such as cattle
and sheep, according to the model.

While their paper does not explore the particulars of what a global
phaseout of animal agriculture would entail, the authors acknowledge that
"the economic and social impacts of a global transition to a plant-based
diet would be acute in many regions and locales ..." and that "it is
likely that substantial global investment will be required to ensure
that people who currently making a living from animal agriculture do not
suffer when it is reduced or replaced." But, they write, "in both cases,
these investments must be compared to the economic and humanitarian
disruptions of significant global warming." Changing attitudes Many
will scoff at the idea that billions of people can be convinced to
switch to a plant-only diet within 15 years. To these skeptics, Eisen
points out that other revolutions have happened in less time. "We went
from having no cellphones to cellphones being ubiquitous in less time
than that. Electricity, cars, solar panels -- all became common in a
relatively short period of time," Eisen said.

Moreover, Brown added, societal attitudes toward food are far from
fixed. "Five hundred years ago, nobody in Italy had ever seen a
tomato. Sixty years ago, nobody in China had ever drunk a Coke. Mutton
was once the most popular meat in America," he said. "People around
the world readily adopt new foods, especially if they are delicious, nutritious, convenient and affordable." The scientists have made all of
the raw data they used, as well as their calculations and the computer
code used to carry out the calculations, publicly available so that
others can make up their own mind.

"The great thing about science is that, in the end, it all comes
down to whether the conclusions are supported by the evidence,"
Brown said. "And in this case, they are." special promotion
Explore the latest scientific research on sleep and dreams
in this free online course from New Scientist -- Sign_up_now_>>> ========================================================================== Story Source: Materials provided by Stanford_University. Original written
by Ker Than. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Michael B. Eisen, Patrick O. Brown. 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. PLOS
Climate, 2022; 1 (2): e0000010 DOI: 10.1371/journal.pclm.0000010 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220201143917.htm

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