lots of charts at link.
"If the world adopted a plant-based diet we would reduce global agricultural
land use from 4 to 1 billion hectares
If everyone shifted to a plant-based diet we would reduce global land use for
agriculture by 75%. This large reduction of agricultural land use would be
possible thanks to a reduction in land used for grazing and a smaller need for
land to grow crops.
by Hannah Ritchie
March 04, 2021
Summary
Half of the world’s habitable land is used for agriculture, with most of this
used to raise livestock for dairy and meat. Livestock are fed from two sources
– lands on which the animals graze and land on which feeding crops, such as
soy and cereals, are grown. How much would our agricultural land use
decline if the world adopted a plant-based diet?
Research suggests that if everyone shifted to a plant-based diet we would
reduce global land use for agriculture by 75%. This large reduction of
agricultural land use would be possible thanks to a reduction in land used for
grazing and a smaller need for land to grow crops. The research also shows
that cutting out beef and dairy (by substituting chicken, eggs, fish or plant-
based food) has a much larger impact than eliminating chicken or fish.
The expansion of land for agriculture is the leading driver of deforestation
and biodiversity loss.
Half of the world’s ice- and desert-free land is used for agriculture. Most of
this is for raising livestock – the land requirements of meat and dairy
production are equivalent to an area the size of the Americas, spanning all
the way from Alaska to Tierra del Fuego.
The land use of livestock is so large because it takes around 100 times as
much land to produce a kilocalorie of beef or lamb versus plant-based
alternatives. This is shown in the chart.1 The same is also true for protein – it
takes almost 100 times as much land to produce a gram of protein from beef
or lamb, versus peas or tofu.
Of course the type of land used to raise cows or sheep is not the same as
cropland for cereals, potatoes or beans. Livestock can be raised on pasture
grasslands, or on steep hills where it is not possible to grow crops. Two-
thirds of pastures are unsuitable for growing crops.2
This raises the question of whether we could, or should, stop using it for
agriculture at all. We could let natural vegetation and ecosystems return to
these lands, with large benefits for biodiversity and carbon sequestration.3 In
an upcoming article we will look at the carbon opportunity costs of using
land for agriculture.
One concern is whether we would be able to grow enough food for everyone
on the cropland that is left. The research suggests that it’s possible to feed
everyone in the world a nutritious diet on existing croplands, but only if we
saw a widespread shift towards plant-based diets.
Land use of foods per 1000 kilocalories
Land use is measured in meters squared (m²) required to produce 1000
kilocalories of a given
food product.
Add food
Beef (beef herd)
119.49 m²
Lamb & Mutton
116.66 m²
Cheese
22.68 m²
Beef (dairy herd)
15.84 m²
Milk
14.92 m²
Pig Meat
7.26 m²
Poultry Meat
6.61 m²
Fish (farmed)
4.7 m²
Eggs
4.35 m²
Tomatoes
4.21 m²
Bananas
3.22 m²
Oatmeal
2.9 m²
Prawns (farmed)
2.88 m²
Citrus Fruit
2.69 m²
Peas
2.16 m²
Nuts
2.11 m²
Cassava
1.86 m²
Groundnuts
1.57 m²
Wheat & Rye
1.44 m²
Apples
1.31 m²
Potatoes
1.2 m²
Root Vegetables
0.89 m²
Rice
0.76 m²
Maize
0.65 m²
Source: Joseph Poore and Thomas Nemecek (2018). Additional calculations
by Our World in Data.
Note: The median year of the studies involved in this research was 2010.
OurWorldInData.org/environmental-impacts-of-food • CC BY
CHART
TABLE
SOURCES
DOWNLOAD
Related:
FAQs: Data on the environmental impacts of food
Related charts:
Land use protein poore
Land use of foods per 100 grams of protein
Land use per kg poore
Land use of foods per kilogram
More plant-based diets tend to need less cropland
If we would shift towards a more plant-based diet we don’t only need less
agricultural land overall, we also need less cropland. This might go against
our intuition: if we substitute beans, peas, tofu and cereals for meat and
dairy, surely we would need more cropland to grow them?
Let’s look at why this is not the case. In the chart here we see the amount of
agricultural land the world would need to provide food for everyone. This
comes from the work of Joseph Poore and Thomas Nemecek, the largest
meta-analysis of global food systems to date.4 The top bar shows the
current land use based on the global average diet in 2010.
As we see, almost three-quarters of this land is used as pasture, the
remaining quarter is cropland.5 If we combine pastures and cropland for
animal feed, around 80% of all agricultural land is used for meat and dairy
production.
This has a large impact on how land requirements change as we shift
towards a more plant-based diet. If the world population ate less meat and
dairy we would be eating more crops. The consequence – as the following
bar chart shows – would be that the ‘human food’ component of cropland
would increase while the land area used for animal feed would shrink.6
In the hypothetical scenario in which the entire world adopted a vegan diet
the researchers estimate that our total agricultural land use would shrink
from 4.1 billion hectares to 1 billion hectares. A reduction of 75%. That’s
equal to an area the size of North America and Brazil combined.
But importantly large land use reductions would be possible even without a
fully vegan diet. Cutting out beef, mutton and dairy makes the biggest
difference to agricultural land use as it would free up the land that is used for
pastures. But it’s not just pasture; it also reduces the amount of cropland we
need.
This is an important insight from this research: cutting out beef and dairy (by
substituting chicken, eggs, fish or plant-based food) has a much larger
impact than eliminating chicken or fish.
Land use of different diets poore nemecek
Less than half of the world’s cereals are fed directly to humans
How is it possible that producing more crops for human consumption needs
less cropland? The answer becomes clear when we step back and look at the
bigger picture of how much crop we actually produce, and how this is used.
In the chart we see the breakdown of what the world’s cereals are used for.
This is split into three categories: direct human food (the rice, oats, wheat,
bread etc. that we eat); animal feed; and industrial uses (which is mainly
biofuels).
Less than half – only 48% – of the world’s cereals are eaten by humans. 41%
is used for animal feed, and 11% for biofuels.
In many countries, the share that is for human consumption is even smaller.
We see this in the map. In most countries across Europe it’s less than one-
third of cereal production is used for human consumption, and in the US only
10% is.7
It’s not just cereals that are diverted towards animal feed and biofuels. It’s
also true of many oilcrops. As we look at in more detail here, only 7% of soy
goes towards human foods such as tofu, tempeh, soy milk and other
substitute products. Most of the rest goes towards oil production which is
split between soybean meal for animal feed and soybean oil. These are co-
products, although by economic value, animal feed dominates.
Cereals allocated to food, animal feed and fuel,
World
Cereal crops allocated to direct human consumption, used for animal feed,
and other
uses – mainly industrial uses such as biofuel production. This is based on
domestic
supply quantity for countries after correction for imports, exports and stocks.
Add country or region
All together
Relative
1961
2020
1970
1980
1990
2000
2010
0%
20%
40%
60%
80%
100%
Industrial uses(often fuel)
Animal feed
Human food
Source: Food and Agriculture Organization of the United Nations
Note: The FAO apply a methodological change from the year 2010 onwards.
OurWorldInData.org/land-use-diets • CC BY
1961
2020
CHART
TABLE
SOURCES
DOWNLOAD
Share of cereals allocated to human food, 2020
The share of domestic cereal supply – after correcting for trade – which is
allocated to direct human consumption, as opposed to being used for animal
feed or industrial uses (such as biofuel production).
No data
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
World
Source: Our World in Data based on the Food and Agriculture Organization of
the United Nations
Note: Data represents the share of cereals available domestically (after
trade) allocated directly to
human food, excluding supply chain losses and seed resown from the crop.
OurWorldInData.org/land-use-diets • CC BY
1961
2020
CHART
MAP
TABLE
SOURCES
DOWNLOAD
Related charts:
Share cereals animal feed
Share of cereals allocated to animal feed
Share cereals industrial uses
Share of cereals allocated to industrial uses (e.g. biofuels)
Livestock waste a lot of energy and protein, but do produce more nutrient-
dense protein sources
Cereals fed to animals are not wasted: they are converted to meat and dairy,
and consumed by humans in the end. But, in terms of calories and total
protein, this process is very inefficient. [What’s true is that animals do
produce high-quality, micronutrient-rich protein – see the box on this
below].8 When you feed an animal, not all of this energy goes into producing
additional meat, milk or eggs. Most is used to simply keep the animal alive.
This is exactly the same for us: most of the calories we eat are used to keep
us alive and maintain our body weight. It’s only when we eat in excess that
we gain weight.
In the charts here we see the energy and protein efficiency of different
animal products.9 This tells us what percentage of the calories or grams of
protein that we feed livestock are later available to consume as meat and
dairy. As an example: beef has an energy efficiency of about 2%. This means
that for every 100 kilocalories you feed a cow, you only get 2 kilocalories of
beef back. In general we see that cows are the least efficient, followed by
lamb, pigs then poultry. As a rule of thumb: smaller animals are more
efficient. That’s why chicken and fish tend to have a lower environmental
impact.
This is why eating less meat would mean eliminating large losses of calories
and thereby reduce the amount of farmland we need. This would free up
billions of hectares for natural vegetation, forests and ecosystems to return.
Energy efficiency of meat and dairy production
The energy efficiency of meat and dairy production is defined as the
percentage of energy (caloric) inputs as feed effectively converted to animal
product. An efficiency of 25% would mean 25% of calories in animal feed
inputs were effectively converted to animal product; the remaining 75%
would
be lost during conversion.
Whole Milk
24%
Eggs
19%
Poultry
13%
Pork
8.6%
Lamb/mutton
4.4%
Beef
1.9%
Source: Alexander et al. (2016). Human appropriation of land for food: the
role of diet. Global
Environmental Change.
OurWorldInData.org/meat-production • CC BY
CHART
TABLE
SOURCES
DOWNLOAD
Protein efficiency of meat and dairy production
The protein efficiency of meat and dairy production is defined as the
percentage of protein inputs as feed effectively converted to animal product.
An efficiency of 25% would mean 25% of protein in animal feed inputs were
effectively converted to animal product; the remaining 75% would be lost
during conversion.
Eggs
25%
Whole Milk
24%
Poultry
19.6%
Pork
8.5%
Lamb/mutton
6.3%
Beef
3.8%
Source: Alexander et al. (2016). Human appropriation of land for food: the
role of diet. Global
Environmental Change.
OurWorldInData.org/meat-production • CC BY
CHART
TABLE
SOURCES
DOWNLOAD
Livestock convert feed to high-quality, micronutrient-rich protein
More of our articles on this topic…
How much of ghgs come from food
Food production is responsible for one-quarter of the world’s greenhouse
gas emissions
Environmental impact of food by life cycle stage
You want to reduce the carbon footprint of your food? Focus on what you
eat, not whether your food is local
Carbon footprint of protein foods 2
How does the carbon footprint of foods compare across the world?
Our World in Data presents the data and research to make progress against
the world’s largest problems.
This blog post draws on data and research discussed in our entry on
Environmental impacts of food production.
Endnotes
This data is based on the global median land use of different food products
as presented in Poore and Nemecek (2018). This meta-analysis looked at the
environmental impacts of foods covering 38,000 farms in 119 countries. For
some foods there is significant variability from the median land use
depending on how it is produced. We look at these differences here.
Poore, J., & Nemecek, T. (2018). Reducing food’s environmental impacts
through producers and consumers. Science, 360(6392), 987-992.
An estimated 65% of land used for grass for grazing cattle is not suitable for
growing crops.
Mottet, A., de Haan, C., Falcucci, A., Tempio, G., Opio, C., & Gerber, P. (2017).
Livestock: on our plates or eating at our table? A new analysis of the
feed/food debate. Global Food Security, 14, 1-8.
Poore, J., & Nemecek, T. (2018). Reducing food’s environmental impacts
through producers and consumers. Science, 360(6392), 987-992.
Hayek, M. N., Harwatt, H., Ripple, W. J., & Mueller, N. D. (2020). The carbon
opportunity cost of animal-sourced food production on land. Nature
Sustainability, 1-4.
Poore, J., & Nemecek, T. (2018). Reducing food’s environmental impacts
through producers and consumers. Science, 360(6392), 987-992.
Note that this breakdown of agricultural land use differs slightly from the
breakdown of global land use from the UN Food and Agriculture Organization
(FAO) for a few reasons. First, this view only includes cropland and pasture
used to produce food. Allocation of crops towards industrial uses e.g.
biofuels is not included. In UN FAO breakdowns, it is included. Secondly, the
amount of land that qualifies as ‘pasture’ depends on definitions surrounding
livestock density and other aspects of land management. The extent of
‘rangelands’ – land used to raise livestock but at a relatively low density –
can vary from study-to-study. So, while the UN FAO data suggests 50% of
habitable land is used for agriculture, Poore and Nemecek (2018) put this
figure at 43%.
This data is sourced from the meta-analysis study by Joseph Poore and
Thomas Nemecek (2018), published in Science. Many other studies have
looked at this question and found exactly the same result: that if everyone
shifted to a vegan diet, we would need less agricultural land (and cropland)
specifically.
Hayek, M. N., Harwatt, H., Ripple, W. J., & Mueller, N. D. (2020). The carbon
opportunity cost of animal-sourced food production on land. Nature
Sustainability, 1-4.
Searchinger, T. D., Wirsenius, S., Beringer, T., & Dumas, P. (2018). Assessing
the efficiency of changes in land use for mitigating climate change. Nature,
564(7735), 249-253.
There is a strong rich-poor split across countries: people in poorer countries
get most of their calories from cereals as they cannot afford much meat and
dairy. This means they cannot afford to divert cereals towards livestock or
biofuels. In India, 93% of cereals are consumed by humans; 95% in Kenya;
and 96% in Botswana.
Tilman, D., & Clark, M. (2014). Global diets link environmental sustainability
and human health. Nature, 515(7528), 518-522.
Shepon, A., Eshel, G., Noor, E., & Milo, R. (2016). Energy and protein feed-to-
food conversion efficiencies in the US and potential food security gains from
dietary changes. Environmental Research Letters, 11(10), 105002.
This is shown as the average conversion efficiency. It can vary a bit
depending on the breed of livestock, what they’re fed, and how they’re
managed. But the overall magnitudes are similar.
Alexander, P., Brown, C., Arneth, A., Finnigan, J., & Rounsevell, M. D. (2016).
Human appropriation of land for food: The role of diet. Global Environmental
Change, 41, 88-98.
World Health Organization, & United Nations University. (2007). Protein and
amino acid requirements in human nutrition (Vol. 935). World Health
Organization.
One way of comparing the quality of different protein sources is using their
Protein Digestibility-Corrected Amino Acid Score (PDCAAS). This score looks
not only at the total protein they provide but also digestibility, and whether
there are particular deficiencies of specific amino acids. Cereals in particular
are often limited in the amino acid, lysine. This gives them a low PDCAAS
score of 42, compared to beef which achieves 92.
Schaafsma, G. (2000). The protein digestibility–corrected amino acid score.
The Journal of Nutrition, 130(7), 1865S-1867S.
Young, V. R., & Pellett, P. L. (1994). Plant proteins in relation to human protein
and amino acid nutrition. The American Journal of Clinical Nutrition, 59(5),
1203S-1212S.
As we noted earlier, protein quality can be scored in terms of its Protein
Digestibility-Corrected Amino Acid Score (PDCAAS). Soy achieves a
PDCAAS of 0.92, comparable to beef at 0.94.
Schaafsma, G. (2000). The protein digestibility–corrected amino acid score.
The Journal of Nutrition, 130(7), 1865S-1867S."
|
|