Vegan and Vegetarian Diets and Our Climate Emergency: Scientific Updates [2015-2021]

By Jeanne Yacoubou, MS

In this article, The Vegetarian Resource Group highlights
several recent (2015 to the present) scientific reports that reveal the
relationships between dietary choices and our climate crisis.

Background on Our Climate Crisis
and Current State of the Emergency

In November 2019, 11,000 scientists from 153 countries
declared a climate emergency in an article published in BioScience.
The emergency is driven by fossil fuel burning releasing greenhouse gases
(GHG), especially carbon dioxide, that began in the early 1800s with
the rise of industry. The burning has accelerated rapidly since then. Life as
we know it on a habitable Earth is at stake.

In January 2021, scientists
new calculations that reveal the underestimation of earlier
predictions about the degree of temperature increase already locked in
from past and current fossil fuel use.

According to the new research, an increase of 2.30C
is guaranteed, but can be delayed if measures are taken now to
significantly reduce or eliminate burning of coal, oil, and methane gas.

Note: The Intergovernmental Panel on Climate Change (IPCC)
stated in a 2018 report that limiting
temperature increase to 1.50C above pre-industrial levels will avert
the worst case scenario of extreme weather and sea level rise. The Paris
Climate Accord
of 2015 is a voluntary agreement among nations to reach this

Emphasizing the gravity and urgency of the matter, 19
wrote in a January 2021 article published in Frontiers in
Conservation Science

“The scale of the threats to the biosphere and all its life forms—including
humanity—is in fact so great that it is difficult to grasp for even
well-informed experts.”

To better grasp the problem and propose solutions, ecologist
William Ripple and several other scientists in January 2021 developed a 6-step
to reduce or eliminate fossil fuel use. Of interest to vegetarians and
vegans, three of the six points are directly related to dietary choice.

  • Short-lived
    pollutant reductions.
    authors target methane, the greenhouse gas 84
      more powerful than carbon
    dioxide. A major source of methane is animal agriculture, especially beef
    production. (Note: Inaccurate assessment of methane
    from fracking and from thawing
    are not considered in making this statement because these data
    are only estimates right now. When confirmed, agriculture’s contribution to
    total methane production would be lessened but still present.) 
  • Habitat
    destruction reductions.
    Deforestation to
    make room for livestock grazing or planting livestock feed is a major concern.
    So, too, is cutting down mangrove
    and peatlands especially for rice paddies and palm oil
    plantations. Palm oil ingredients are found in hundreds of food and cosmetic
  • Fewer
    animal foods and more plants in human diets. Waste food less.
    Not only an important way to reduce water and land use
    to produce food, significant reductions in greenhouse gases

Scale of Animal Agriculture Impact on Climate Change: Carbon

How much does animal agriculture contribute to our climate

The World
Resources Institute
assembled the latest available data (2016) from
credible sources including the International Energy Agency and concluded:

  • Total
    annual world emissions was 49.4 GT CO2eq. (73% carbon dioxide CO2,
    17% methane CH4, and 6% nitrous oxide NO2)
  • The
    top three carbon polluters: China
    (26%), USA
    (13%) European Union (8%)
  • The
    breakdown of major emissions by sector: Energy in transportation (16%); Energy
    for electricity/heating (30%); Energy for manufacturing/construction (12%)
  • Agriculture

Made up of 6% livestock/manure and 6% from soils. Manure is a
major source of methane and nitrous oxide (another extremely potent greenhouse
gas).  Fertilizer is a major source of
nitrous oxide.

  • Land
    use change, forestry 7% (burning 4%)

In a July
2019 report
published by the World Resources Institute, the World Bank
Group, the United Nations Environment Programme, and the United Nations
Development Programme, further information is given about livestock’s
contributions to environmental use and greenhouse gas emissions: “Ruminant
livestock (cattle, sheep, and goats) use two-thirds of global agricultural land
and contribute roughly half of agriculture’s production-related emissions.”

Despite the enormity of the carbon pollution stemming from
livestock, the authors do not clearly recommend a switch to a vegan diet as a
way to mitigate the impact of livestock on our climate emergency. They mention
only “…shifting the diets of high meat consumers toward plant-based foods”
and “plant-based beef substitutes.”

In a 2019 special report
titled Climate Change and Land, the IPCC mentions “dietary choices” in
reference to how climate change can be curbed, but does not specify vegan or
vegetarian diets.

From the report: “Balanced diets, featuring plant-based foods,
such as those based on coarse grains, legumes, fruits and vegetables, nuts and
seeds, and animal-sourced food produced in resilient, sustainable and
low-greenhouse gas emission systems, present major opportunities for adaptation
and mitigation while generating significant co-benefits in terms of human

Other notable points from this document:

  • 70% of
    freshwater is used for agriculture
  • 25-30%
    of all food is wasted (responsible for 8-10% of all emissions).

Recent Scientific Reports on Carbon Emissions and Animal
Agriculture in Relation to Plant-based Diets

The Vegetarian Resource Group looked closely at the
environmental consequences of animal agriculture with its 2009
on the United Nations’ report titled Livestock’s Long Shadow.
In that piece, the focus was on water pollution caused by livestock.

Since that time, many researchers have analyzed the carbon
associated with raising animals intensively for food. Here are
brief summaries of some of their reports.

“The climate
mitigation gap: education and government recommendations miss the most
effective individual actions”

1. In 2017, Seth Wynes and Kimberly A Nicholas published an article that quantified the effects of lifestyle
choices in terms of tons of carbon dioxide equivalents, tCO2eq
(taking into account methane, nitrous oxide and other chemicals that have
substantial global warming potential) produced when people engage in certain
activities. They concluded that individuals would contribute the greatest
reduction by:

  • Having
    fewer children (58.6 tCO2eq saved every year per child)*
  • Going
    car-less (2.4 tCO2eq saved per year)*
  • Avoiding
    flying (1.6 tCO2eq saved per round transatlantic trip)*
  • Buying
    green energy (1.5 tCO2eq saved per year)
  • Buying
    a more efficient gasoline-powered car (1.19 tCO2eq saved per year)
  • Buying
    an electric car (1.15 tCO2eq saved per year)
  • Choosing
    a plant-based diet (0.8 tCO2eq per year)*

According to the authors, all of the above actions are
considered “high-impact (i.e., low-emissions).” The four which are asterisked
are recommended as the most important you can take to lower your
personal fossil fuel footprint. Although they do not use the word “vegan” to
describe the “plant-based diet,” it appears from the writing that a vegan diet
is implied. The VRG has reached out to the authors on this point, but have not
yet received a response.

“Calculation of external climate costs for food highlights inadequate pricing of animal products”

2. A report published in December 2020
conducted life cycle assessments of
various agricultural products in Germany. The most significant
finding was that there is practically no difference between the carbon
emissions resulting from organic versus conventional beef production. Organic
chicken fared worse than conventionally raised chicken in terms of its
contribution to greenhouse gases. Organic and non-organic cow’s milk had
similar carbon emission profiles.

By contrast, organic plant foods are responsible for 50% less
emissions than plant foods treated with chemical fertilizers and pesticides.
All plant production resulted in significantly less carbon emissions than
animal foods.

“Substituting beans for beef as a contribution toward US climate change targets”

3. A study
published in 2017 compared the
environmental costs of beef versus beans. It concluded: “Our results demonstrate
that substituting one food for another, beans for beef, could achieve
approximately 46 to 74% of the reductions needed to meet the 2020 GHG target
for the US.
In turn, this shift would free up 42% of US cropland (692,918 km2).”

“The environmental cost of protein food choices”

4. An earlier look at this topic from some of the same
researchers in 2015
concluded: “To produce 1 kg of protein from kidney beans required approximately
eighteen times less land, ten times less water, nine times less fuel, twelve
times less fertilizer and ten times less pesticide in comparison to producing 1
kg of protein from beef. Compared with producing 1 kg of protein from chicken
and eggs, beef generated five to six times more waste (manure) to produce 1 kg
of protein.”

“Food in the Anthropocene: the
EAT–Lancet Commission on healthy diets from sustainable food systems”

5. The EAT-Lancet
(2019) published an extensive review of the environmental
consequences of food choices. Its major conclusions echoed many of the findings
noted here from other researchers.

Additionally, this report showed changes in food production
practices (such as using feed additives, manure management, better feed conversion ratios) could decrease total greenhouse gas
emissions by only 10%. However, dietary changes that increase plant
foods could decrease emissions by 80%.

EAT-Lancet also divided up agriculture’s greenhouse gas share
in this manner (top three listed here):

“Which Diet Has the Least Environmental Impact on Our Planet? A Systematic Review of Vegan, Vegetarian and Omnivorous Diets”

6. A 2019
review article
from the journal Sustainability compared many studies
looking at environmental impacts of vegan, vegetarian, and omnivore diets. Some
of the relevant points included:

  • “Livestock
    farming uses 70% of agricultural
    overall and a third of arable
    . As such, it plays a major role in CO2 release and
    biodiversity loss from deforestation.”
  •  “Many vegans replace animal-based products
    with processed plant-based meat and dairy substitutes (e.g., seitan burger and
    soy yoghurt) instead of consuming the unprocessed, plant-based nutritious
    foods…The vegan diet may not have a lower environmental footprint than the
    lacto-ovo vegetarian diet. The reason for this is that vegans tend to replace
    animal-based products in their diet by industrially, highly processed
    plant-based meats and dairy substitutes.”
  • “The
    reviewed studies indicate the possibility of achieving the same environmental
    impact as that of the vegan diet, without excluding the meat and dairy food
    groups, but rather, by reducing them substantially.”

Takeaways on Plant-based Diets, Climate, and Environment

Agriculture (12%) and the burning of forests (4%) to plant
feed crops or graze cattle are responsible for approximately 16% of all
greenhouse gas emissions. This is comparable to the carbon emissions from the
transportation sector.

A July 2019 joint report from several major international organizations
stated: “Ruminant livestock (cattle, sheep, and goats) use two-thirds of global
agricultural land and contribute roughly half of agriculture’s
production-related emissions.”

As a rough estimate using the information of the two
paragraphs above: 2/3 x 12% = 8% of all emissions from ruminant production + 4%
from burning = 12% out of the total 16% from agricultural emissions is due to
ruminant production alone.

There are ways to reduce significantly animal agriculture’s
contribution to our climate crisis by switching to a vegan or vegetarian diet.
In fact, the EAT-Lancet
in 2019 stated that dietary changes which increase plant foods in
human diets could decrease carbon emissions (from the agricultural sector) by 80%.

Unfortunately, major international organizations and
mainstream media do not clearly make the recommendation to switch to a vegan or
vegetarian diet for climate change mitigation.

Individual actions, including switching to a vegan or
vegetarian diet, to curb the negative effects of our climate crisis matter by
reducing personal fossil fuel footprints. They also have a bigger impact in
that they serve
as examples
for others to emulate.

However, systemic change – notably the drastic and immediate
reduction or elimination of fossil fuel use – is needed to prevent worst case
scenarios of extreme weather and sea level rise from happening even more than
they already are.

Note from the Editor:

See other environmental articles from The Vegetarian Resource Group at: