Erratum 22 February 2019. See Erratum.
R ES E A RC H

SUSTAINABILITY

Reducing food’s environmental
impacts through producers
and consumers
J. Poore1,2* and T. Nemecek3W

ith current diets and production practices, feeding 7.6 billion people is degrading terrestrial and aquatic ecosystems,
depleting water resources, and driving
climate change (1, 2). It is particularly
challenging to find solutions that are effective
across the large and diverse range of producers
that characterize the agricultural sector. Morethan 570 million farms produce in almost all theworld’s climates and soils (3), each using vastlydifferent agronomic methods; average farm sizes
vary from 0.5 ha in Bangladesh to 3000 ha inAustralia (3); average mineral fertilizer use ranges
from 1 kg of nitrogen per ha in Uganda to 300 kg
in China (4); and although four crops provide halfof the world’s food calories (4), more than 2 million
distinct varieties are recorded in seed vaults (5).
Further, products range from minimally to heavily
processed and packaged, with 17 of every 100 kg offood produced transported internationally, increasing to 50 kg for nuts and 56 kg for oils (4).
Previous studies have assessed aspects of thisheterogeneity by using geospatial data sets (6–8),
but global assessments using the inputs, outputs,
and practices of actual producers have been limited by data. The recent rapid expansion of thelife cycle assessment (LCA) literature is providing
this information by surveying producers aroundthe world. LCA then uses models to translate producer data into environmental impacts with sufficient accuracy for most decision-making (9–11).
To date, efforts to consolidate these data or build
new large-scale data sets have covered greenhousegas (GHG) emissions only (8, 12, 13), agriculture
only (13–16), small numbers of products (8, 14–16),

1
Department of Zoology, University of Oxford, New Radcliffe
House, Oxford OX2 6GG, UK. 2School of Geography and theEnvironment, University of Oxford, South Parks Road, Oxford
OX1 3QY, UK. 3Agroscope, Agroecology and Environment Research
Division, LCA Research Group, CH-8046 Zürich, Switzerland.

*Corresponding author. Email: joseph.poore@queens.ox.ac.uk

Poore et al., Science 360, 987–992 (2018)

1 June 2018

and predominantly Western European producers(12–16) and have not corrected for important methodological differences between LCAs (12–16). Here,
we present a globally reconciled and methodologically harmonized database on the variation in food’s
multiple impacts. Our results show the need for
far-reaching changes in how food’s environmental
impacts are managed and communicated.
Building the multi-indicatorglobal databaseWe derived data from a comprehensive metaanalysis, identifying 1530 studies for potential
inclusion, which were supplemented with additional data received from 139 authors. Studies
were assessed against 11 criteria designed tostandardize methodology, resulting in 570 suitable studies with a median reference year of2010 (17). The data set covers ~38,700 commercially viable farms in 119 countries (fig. S2) and
40 products representing ~90% of global protein and calorie consumption. It covers five important environmental impact indicators (18):
land use; freshwater withdrawals weighted by
local water scarcity; and GHG, acidifying, andeutrophying emissions. For crops, yield represents output for a single harvest. Land use includes multicropping (up to four harvests peryear), fallow phases (uncultivated periods between crops), and economic allocation to crop
coproducts such as straw. This makes it a stronger indicator of both farm productivity andfood security than yield.
The system we assess begins with inputs (theinitial effect of producer choice) and ends at retail (the point of consumer choice) (fig. S1). For
each study, we recorded the inventory of outputs and inputs (including fertilizer quantity
and type, irrigation use, soil, and climatic conditions). Where data were not reported, for example, on climate, we used study coordinatesand spatial data sets to fill gaps. We recorded

Environmental impacts of the entire
food supply chain
Today’s food supply chain creates ~13.7 billion
metric tons of carbon dioxide equivalents (CO2eq),
26% of anthropogenic GHG emissions. A further
2.8 billion metric tons of CO2eq (5%) are caused
by nonfood agriculture and other drivers of deforestation (17). Food production creates ~32%of global terrestrial acidification and ~78% of
eutrophication. These emissions can fundamentally alter the species composition of natural
ecosystems, reducing biodiversity and ecologicalresilience (19). The farm stage dominates, representing 61% of food’s GHG emissions (81%including deforestation), 79% of acidification,and 95% of eutrophication (table S17).
Today’s agricultural system is also incredibly
resource intensive, covering ~43% of the world’s
ice- and desert-free land. Of this land, ~87% is
for food and 13% is for biofuels and textile crops
or is allocated to nonfood uses such as wool andleather. We estimate that two-thirds of freshwater
withdrawals are for irrigation. However, irrigation returns less water to rivers and groundwater
than industrial and municipal uses and predominates in water-scarce areas and times ofthe year, driving 90 to 95% of global scarcityweighted water use (17).
Highly variable and skewed
environmental impacts
We now group products by their primary dietaryrole and express impacts per unit of primarynutritional benefit (Fig. 1 and fig. S3). Immediately apparent in our results is the high variationin impact among both products and producers.
Ninetieth-percentile GHG emissions of beefare 105 kg of CO2 eq per 100 g of protein, and
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Food’s environmental impacts are created by millions of diverse producers. To identify solutions
that are effective under this heterogeneity, we consolidated data covering five environmental
indicators; 38,700 farms; and 1600 processors, packaging types, and retailers. Impact can vary
50-fold among producers of the same product, creating substantial mitigation opportunities.
However, mitigation is complicated by trade-offs, multiple ways for producers to achieve low
impacts, and interactions throughout the supply chain. Producers have limits on how far they can
reduce impacts. Most strikingly, impacts of the lowest-impact animal products typically exceed
those of vegetable substitutes, providing new evidence for the importance of dietary change.
Cumulatively, our findings support an approach where producers monitor their own impacts,
flexibly meet environmental targets by choosing from multiple practices, and communicate theirimpacts to consumers.

environmental impacts at each stage of the supply chain. For GHG emissions, we further disaggregated the farm stage into 20 emission sources.
We then used the inventory to recalculate all
missing emissions. For nitrate leaching andaquaculture, we developed new models for thisstudy (17).
Studies included provided ~1050 estimatesof postfarm processes. To fill gaps in processing, packaging, or retail, we used additional
meta-analyses of 153 studies providing 550 observations. Transport and losses were included
from global data sets. Each observation was
weighted by the share of national production it
represents, and each country by its share of
global production. We then used randomization to capture variance at all stages of the
supply chain (17).
We validated the global representativeness ofour sample by comparing average and 90thpercentile yields to Food and Agriculture Organization (FAO) data (4), which reconcile towithin ±10% for most crops. Using FAO foodbalance sheets (4), we scaled up our sample data.
Total arable land and freshwater withdrawals
reconcile to FAO estimates. Emissions from deforestation and agricultural methane fall within
ranges of independent models (17).

Erratum 22 February 2019. See Erratum.
R ES E A RC H | R E S EA R C H A R T I C LE

GHG Emissions(kg CO2eq)

A 100g protein n 0

25

50

20

Beef (beef herd) 724

200

50

42

164

Lamb & Mutton 757

12

20

30

185

9.1

17

7.3

22

18

0.4

2.0
41

5

10

0

15

Crustaceans (farmed) 1.0k

5.4

5

10

15

5.1

11

4.4

4.6

7.6

4.8

11

Fish (farmed) 612

2.5

6.0

0.4

3.7

Poultry Meat 326

2.4

5.7

3.8

7.1

Eggs 100

2.6

4.2

4.0

5.7

Tofu 354

1.0

2.0

1.1

2.2

Groundnuts 100

0.6

1.2

1.8

3.5

0.5

0.8

4.6

7.3

0.3

0.4

1.2

3.4

-2.2 0.3

2.7

7.9

1.0

2.7

1.7

4.6

1.7

3.2

1.1

8.9

0.6

1.0

0.3

0.7

10th pctl.
ruminant
meat

Peas 438
Nuts 199
Grains 23k

1 liter

0

2

4

6

Milk 1.8k
Soymilk 354

1000 kcal

0

1

2

0

3

3

0

6

2

9

4

6

Cassava 288

0.4

1.4

0.8

1.9

Rice (flooded) 7.8k

0.4

1.2

0.3

0.8

Oatmeal 139

0.3

0.9

1.1

2.9

Potatoes 604

0.2

0.6

0.6

1.2

Wheat & Rye (Bread) 8.8k

0.3

0.6

0.4

1.4

Maize (Meal) 6.2k

0.2

0.4

0.3

0.7

D

E

1 liter

5

10

15

30
1.7

2.4

Soybean Oil 497

2.4

6.3

5.3

11

Olive Oil 411

2.9

5.4

7.9

26

Rapeseed Oil 1.8k

2.5

3.8

5.2

11

Sunflower Oil 519

2.5

3.6

8.4

18

Tomatoes 855

0.4

2.1

0.1

0.8

0

1

2

3

0

0.5

1

1.5

Brassicas 40

0.2

0.5

0.2

0.6

Onions & Leeks 37

0.3

0.5

0.1

0.4

Root Vegetables 43

0.2

0.4

0.2

0.3

0

1

2

3

0

2

4

6

Berries 183

0.8

1.5

0.3

2.4

Bananas 246

0.6

0.9

0.3

1.9

Apples 125

0.3

0.4

0.3

0.6

0.1

0.4

0.4

0.9

1.2

2.0

1.2

1.8

1kg

0

2

4

6

Cane Sugar 116
Beet Sugar 209

I

20

7.3

Citrus 377

H

10

3.6

1kg

G

0

Palm Oil 220

1kg

F

0

1 unit

0

0.2

0.4

0
0.9

3.2

1.2

1.8

0.6

0

1

2

0.2

3

0.4

4

0.6

Beer (5% ABV) 695

0.14 0.24

0.05 0.22

Wine (12.5% ABV) 154

0.07 0.14

0.07 0.14

1 serving

0

3

6

9

0

3

6

9

Dark Chocolate (50g) 162-0.01 2.3

1.7

Coffee (15g, 1 cup) 346

0.08 0.4

0.13 0.3

Eutroph.
(g PO43–eq)

Scty. Water(kL eq)

75

150 0

75

150 0

50

100

0

75

150 0

75

150 0

50

100

0

15

30 0

10

20 0

50

100

0

5

10 0

5

10 0

20

40

0

30

60 0

30

60 0

100

200

0

10

20 0

10

20 0

10

20

0

10

20 0

10

20 0

30

60

0

20

40 0

20

40 0

20

40

0

1

2 0

0.5

1 0

0.1

0.2

0

5

10 0

10

20 0

0.1

0.2

3.4

Median Mean
10th percentile

90th percentile

Fig. 1. Estimated global variation in GHG emissions, land use, terrestrial acidification,
eutrophication, and scarcity-weighted freshwater withdrawals, within and between
40 major foods. (A) Protein-rich products. Grains are also shown here given that they
contribute 41% of global protein intake, despite lower protein content. (B) Milks.
(C) Starch-rich products. (D) Oils. (E) Vegetables. (F) Fruits. (G) Sugars. (H) Alcoholic
beverages (1 unit = 10 ml of alcohol; ABV, alcohol by volume). (I) Stimulants. n = farmor regional inventories. Pc and pctl., percentile; scty., scarcity.
Poore et al., Science 360, 987–992 (2018)

1 June 2018

land use (area multiplied by years occupied) is
370 m2·year. These values are 12 and 50 times
greater than 10th-percentile dairy beef impacts(which we report separately given that its production is tied to milk demand). Tenth-percentile
GHG emissions and land use of dairy beef arethen 36 and 6 times greater than those of peas.
High variation within and between protein-richproducts is also manifest in acidification, eutrophication, and water use.
Within the major crops wheat, maize, and rice,90th-percentile impacts are more than three times
greater than 10th-percentile impacts on all fiveindicators. Within major growing areas for thesecrops (the Australian wheat belt, the U.S. cornbelt, and the Yangtze river basin), land use becomes less variable, but we observe the samehigh levels of variation in all other indicators.
This variability, even among producers in similar
geographic regions, implies substantial potential
to reduce environmental impacts and enhance
productivity in the food system.
For many products, impacts are skewed byproducers with particularly high impacts. This
creates opportunities for targeted mitigation,
making an immense problem more manageable.
For example, for beef originating from beef herds,
the highest-impact 25% of producers represent
56% of the beef herd’s GHG emissions and 61% of
the land use (an estimated 1.3 billion metric tonsof CO2 eq and 950 million ha of land, primarily
pasture). Across all products, 25% of producers
contribute on average 53% of each product’s environmental impact (fig. S3). For scarcity-weighted
freshwater withdrawals, the skew is particularly pronounced: Producing just 5% of the world’s
food calories creates ~40% of the environmental
burden. We will now explore how to access thesemitigation opportunities through heterogenous
producers.
Mitigation through producers
Enable producers to monitor
multiple impacts
The first step in mitigation is estimating producer impacts. Prior research [e.g., (7, 8, 14)] hassuggested that readily measurable proxies predict farm-stage impacts, avoiding the need for
detailed assessment. From our larger data set,
which includes more practices and geographies
than prior studies, we assess the predictive powerof common proxies, including crop yield, nitrogen use efficiency, milk yield per cow, liveweight
gain, pasture area, and feed conversion ratios.
Although most proxies significantly covary with
impact, they make poor predictors when usedalone, explaining little of the variation among
farms (coefficient of determination R2 = 0 to 27%
in 47 of 48 proxy-impact combinations assessed)(fig. S4).
Prior research has also suggested using one
impact indicator to predict others (20). We findweakly positive and sometimes negative relationships between indicators. For similar products
globally, correlations between indicators are low(R2 = 0 to 30% in 26 of 32 impact-impact combinations assessed) (fig. S4). Pork, poultry meat,
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Cheese 1.9k
Pig Meat 116

Other Pulses 115

C

100

10th
300 Pc Mean 0

Beef (dairy herd) 490
0

B

Acid.
(g SO2eq)

Land Use(m2year)10th
75 Pc Mean 0

Erratum 22 February 2019. See Erratum.
R ES E A RC H | R E S EA R C H A R T I C LE

Set and incentivize mitigation targets

To meet these targets, policy might encourage widespread adoption of certain practices. However, theenvironmental outcomes of many practices, such asconservation agriculture (23), organic farming (fig.
S6), and even integrated systems of best practice(24), are highly variable. Using our data set, we cangeneralize these findings. To do this, we disaggregate each environmental indicator into its sources
or drivers. We consider practice change as a package of measures that targets one or more of thesesources. If producers have different impact sources,
the effects of practice change will be variable.
We find that sources of impact vary considerably among farms producing the same product(Fig. 2 and figs. S7 to S9). Priority areas for
reducing impact for one farm may be immaterial
for another. For example, measures to reduce direct nitrous oxide emissions from synthetic andorganic fertilizer, such as biochar application, areincluded in many mitigation estimates (25). However, for a third of global crop calorie production,
Poore et al., Science 360, 987–992 (2018)

1 June 2018

C Below median GHG emissions wheat farms

100%

75%

Electricity & Fuel
Synthetic
DirectFertilizer
Indirect(N2O)
Organic Fertilizer (N2O)

50%

Crop Residue
Urea (CO2)25%

Lime (CO2)Residue Burning
Drying0%
Cyprus,Australia, Australia,
irrigatedconventional no-till,residue burnt

0% 25% 50% 75% 100%Contribution of each source to farmstage GHG emissions
Distribution

Germany,
Nepal,
organic raised beds

10th
90th
Percentiles

B Beef farms

Concentrate Feed (incl.
land use change)
Pasture Management

D Below median GHG emissions beef farms

100%
75%

HousingEnteric Fermentation (CH4)50%

Manure Management (CH4)
ManureDirectManagement
Indirect(N2O)
0% 25% 50% 75% 100%Contribution of each source to farmstage GHG emissions

25%

Australia,
grass-fed

China,
Brazil,Denmark,
Canada,improved
feedlot confinement dairy, 9mo
at slaughter
pasture with implants dairy

0%

Fig. 2. Contributions of emission sources to total farm-stage GHG emissions. (A and B) Graybars show 10th- and 90th-percentile contributions. Shaded bars represent the distribution. For
example, the 90th-percentile contribution of organic fertilizer N2O to farm-stage emissions is16%, but for most wheat producers the contribution is near 0%. Density is estimated using a
Gaussian kernel with bandwidth selection performed with biased cross-validation. (C and D)
Contributions of emission sources for example producers with below-median GHG emissions.

these emissions represent less than 5% of farmstage GHGs. It may be the case that low-impact
farms have similar impact drivers. We again findvariable sources of impact, even for low-impact
farms (Fig. 2, C and D). Reducing impacts means
focusing on different areas for different producers
and, by implication, adopting different practices.
To explore this further, we use sensitivity analysis(26) to decompose the variance in each product’s
impact into its sources. Numerous sources contribute to variance (fig. S10). Most notably, for all
crop calorie production globally, differences in fallow duration and multiple cropping drive 40% of
the variance in land use. This is important as moststrategies to increase productivity are focused onincreasing single crop yields (27). But for many
producers, increasing cropping intensity throughthe use of early-maturing varieties, intercropping,catch crops, and enhanced irrigation can provide
more economically viable and trade-off–free ways
to boost productivity and reduce impacts (27).
Geography plays a major role in this variation
and affects the economic and environmental
desirability of different practices (28). However,at the heart of agriculture is changing site conditions to enhance productivity (such as liming,
terracing, or installing drainage), meaning thatstatements on the importance of geography have
limitations. Nevertheless, some impact sources
stand out. We find that freshwater aquaculture
ponds create 0 to 450 g of methane per kg of
liveweight (for context, enteric fermentationin dairy cows creates ~30 to 400 g per kg of liveweight). Of this variation, a third is explained bytemperature (17), which accelerates methanogenesis and net primary production. Improving
aeration and limiting addition of surplus feed
to ponds can abate these emissions, particularly
important in warm countries. Further, for every
kilogram of nitrogen applied to crops, between
60 and 400 g is lost in reactive forms. Of thiswide range, ~40% is explained by site conditions,
including soil pH, temperature, and drainage(17). Prior research has also found that the potential of soil to store carbon varies significantlywith soil properties, slope, and prior practice (29).
Providing producers with multiple ways toreduce their environmental impacts recognizes
the variability in sources and drivers of impact
but requires a step change in thinking: that practices such as conservation agriculture or organic
farming are not environmental solutions in themselves but options that producers choose fromto achieve environmental targets.
However, some practice changes can be pursued across all producers. Methane from flooded
rice, enteric methane from ruminants, and concentrate feed for pigs and poultry are sizeable
globally, representing 30% of food’s GHG emissions; are material for all producers, contributing
at least 17% of farm-stage emissions (Fig. 2B andfig. S7); and can be mitigated with relatively tradeoff–free approaches such as shorter and shallower
rice flooding (30), improving degraded pasture
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Meet targets by choosing from multiple
practice changes

Seed
Fertilizer & Pesticide
Manufacture
Equipment

Contribution of each source

When land use or emissions are low, we findtrade-offs between indicators for many crops(fig. S5). This reflects diminishing marginal yieldwith increasing inputs as crops tend toward theirmaximum yields (22). For example, for alreadylow-emission Northern European barley farms,
halving land use can increase GHG emissions per
kilogram of grain by 2.5 times and acidification
by 3.7 times. To explore trade-offs further, we pairobservations from the same study, location, andyear that assess a practice change (fig. S6). Of thenine changes assessed, only two (changing frommonoculture to diversified cropping and improving degraded pasture) deliver statistically significant
reductions in both land use and GHG emissions.
Geography influences these trade-offs. For example, in the Australian wheat belt, where farmers
practice low-rainfall, low-input farming, we findthat both output per hectare and GHG emissions
are in the bottom 15% globally. The environmental
and social importance of different impacts also
varies locally, given land scarcity, endemic biodiversity, and water quality, among other factors.
Setting regional and sector-specific targets will
help producers navigate trade-offs and makechoices that align with local and global priorities.

A Wheat farms

Contribution of each source to farm-stage GHG emissions

and milk show higher correlations between acidification and eutrophication (R2 ≤ 54%), explainedby the dominant role of manure in these impacts,
but this does not generalize to other products orindicators. The same conclusion holds for farms
in similar geographies or systems (fig. S5).
Monitoring multiple impacts and avoiding
proxies supports far better decisions and helps
prevent harmful, unintended consequences. However, two recent studies suggest that data onpractices and geography, required to quantify
impacts, must come directly from producers(11, 21), that quantifying impacts with the useof satellite or census data misses much of thevariation among farms.

Erratum 22 February 2019. See Erratum.
R ES E A RC H | R E S EA R C H A R T I C LE

GHG Emissions (kg CO2eq 100g protein–1)

A

GHG Emiss.
(kg CO2eq L–1)

Land Use Change

0.5

12.0

2.1
Avg. veg. proteins(excluding nuts)

2.1

1.3
1.0
0.6
0.3

0.5

0.5

0.5

0.20

0.6

0.5

0.2

0.2

0.1

0.21

-0.2

B

0.02

-0.23

2.7

0.2
2.0

1.8

1.8

1.6

Avg. veg.
proteins

2.7

2.1
1.4 1.4-0.76

10th pctl.
veg. proteins

Crop Production & Feed Transport

1.7

1.6

1.4

1.4

0.1

1.1
0.8
0.5

0.6

0.77
0.54

Producer mitigation limits and the roleof consumers

Livestock & Aquaculture
28
15

1.5

14
11

1.0

9.0
6.0

6.0

5.0

3.7
1.9

Beef
(beef herd)

Lamb &
MuttonBeef Crustaceans Cheese(dairy herd) (farmed)

3.5
1.5 1.0

0.9

0.5 0.5

1.2 0.4

Pig MeatFish(farmed)Poultry
Meat

Eggs

Milk

10th Percentile (dark shaded box)

Mean (light shaded box)

Fig. 3. Mean and 10th-percentile GHG emissions of protein-rich products across three major
production stages. (A to C) Red lines represent average vegetable protein emissions, and bluelines represent 10th-percentile emissions. The gray line represents average emissions excluding
nuts, which can temporarily sequester carbon if grown on cropland or pasture. To calculate
10th-percentile emissions by stage, we averaged across farms that have total emissions between
the 5th and 15th percentiles, controlling for burden shifting between stages.

(fig. S6), and improving lifetime animal productivity (8). Further, emissions from deforestationand cultivated organic soils drive on average
42% of the variance in each product’s agricultural GHG emissions (fig. S10) and dominate
the highest-impact producers’ emissions (fig. S11),
further justifying ongoing efforts to curb forest
loss and limit cultivation on peatlands.
Communicate impacts up the
supply chain
Processors, distributors, and retailers can substantially reduce their own impacts. For any product,
90th-percentile postfarm emissions are 2 to 140
times larger than 10th-percentile emissions, indicating large mitigation potential (fig. S12). For
example, returnable stainless steel kegs create just
20 g of CO2eq per liter of beer, but recycled glass
bottles create 300 to 750 g of CO2eq, and bottles
sent to landfills create 450 to 2500 g of CO2eq.
Processing, more durable packaging, andgreater usage of coproducts can also reduce foodwaste. For example, wastage of processed fruitand vegetables is ~14% lower than that of fresh
fruit and vegetables, and wastage of processedfish and seafood is ~8% lower (24). Providing
processors and retailers with information about
the impacts of their providers could encourage
Poore et al., Science 360, 987–992 (2018)

1 June 2018

them to reduce waste where it matters most.
For products such as beef, distribution and retaillosses contribute 12 to 15% of emissions (fig. S13),
whereas the sum of emissions from packaging,transport, and retail contributes just 1 to 9%.
Here, reducing losses is a clear priority.
As a third strategy, procurement could sourcefrom low-impact farms. Although this strategy isimportant, and possible only with information
about the impacts of providers, it has clear limitations. To be effective, it relies on high-impact
production not simply being purchased elsewherein the market. The case of the Roundtable on
Sustainable Palm Oil (RSPO) shows that this is
hard to achieve: despite one-fifth of 2017 palm oil
production being certified, there remains virtually no demand in China, India, and Indonesia(31). Alternatively, this strategy would be effective if higher prices for sustainable production incentivized low-impact producers to increase
output or high-impact producers to change practices. The case of organic food shows how passing
premiums to consumers limits total market size
and widespread practice change.
However, processors and retailers routinely
demand that products meet taste, quality, andfood safety standards. These markets are concentrated, with just 10 retailers representing

Though producers are a vital part of the solution, their ability to reduce environmental impacts
is limited. These limits can mean that a producthas higher impacts than another nutritionallyequivalent product, however it is produced.
In particular, the impacts of animal products
can markedly exceed those of vegetable substitutes(Fig. 1), to such a degree that meat, aquaculture,eggs, and dairy use ~83% of the world’s farmland
and contribute 56 to 58% of food’s different emissions, despite providing only 37% of our protein and
18% of our calories. Can animal products be produced with sufficiently low impacts to redress thisvast imbalance? Or will reducing animal productconsumption deliver greater environmental benefits?
We find that the impacts of the lowest-impact
animal products exceed average impacts of substitute vegetable proteins across GHG emissions,eutrophication, acidification (excluding nuts), andfrequently land use (Fig. 1 and data S2). These
stark differences are not apparent in any productgroups except protein-rich products and milk.
Although tree crops can temporarily sequester
carbon and reduce nutrient leaching, the impactof nuts is dominated by low-yielding cashews
and water-, fertilizer-, and pesticide-intensive
almonds. Production of nuts doubled between
2000 and 2015 (4), and more work is required to
improve their resource use efficiency. Althoughaquaculture can have low land requirements, inpart by converting by-products into edible protein, the lowest-impact aquaculture systems still
exceed emissions of vegetable proteins. This challenges recommendations to expand aquaculture(1) without major innovation in production practices first. Further, though ruminants convert~2.7 billion metric tons of grass dry matter, of
which 65% grows on land unsuitable for crops(34), into human-edible protein each year, theenvironmental impacts of this conversion are
immense under any production method practiced today.
Using GHG emissions (Fig. 3), we identified five
primarily biophysical reasons for these results.
These reasons suggest that the differences between
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C

0.11
0.09

0.8

52% of U.S. grocery sales and 15% of global sales(32). This sometimes means that standards
achieve market transformation (33), where virtually all producers adhere to gain market access.
A fourth strategy for producers is setting environmental standards. These are particularly
important: Although many environmental issues
can be monitored and mitigated in a flexible
way, issues such as harmful pesticide usage anddeforestation require strict controls, and issues
such as on-farm biodiversity are hard to quantify(28). Procurement, farming organizations, and international policy-makers must come together toimplement a safety net for global agriculture—comprehensive standards to manage the worst
and hardest-to-quantify environmental issues,
extending the successes of existing schemes andenabling a flexible mitigation approach to operate effectively.

Erratum 22 February 2019. See Erratum.
R ES E A RC H | R E S EA R C H A R T I C LE

Farms

Monitor multiple
impacts

Meet targets bychoosing frommultiple practicechanges

Processors & Retailers

Validate andcommunicate
impacts

Requiresustainability
standards

PolicyResearchers

Monitor multiple
impacts using
supply-chain data

Consumers

Validate andcommunicate
impacts

Meet targets

Set and incentivize mitigation targets
Define and regulate sustainability standards

Incentivize
sustainableconsumption

Provide multiple mitigation options

Fig. 4. Graphical representation of the mitigation framework.

Mitigation through consumers
Today, and probably into the future, dietarychange can deliver environmental benefits ona scale not achievable by producers. Moving fromcurrent diets to a diet that excludes animal products (table S13) (35) has transformative potential,
reducing food’s land use by 3.1 (2.8 to 3.3) billion ha(a 76% reduction), including a 19% reductionin arable land; food’s GHG emissions by 6.6 (5.5 to7.4) billion metric tons of CO2eq (a 49% reduction);
acidification by 50% (45 to 54%); eutrophication by
49% (37 to 56%); and scarcity-weighted freshwater
withdrawals by 19% (−5 to 32%) for a 2010 reference year. The ranges are based on producing new
vegetable proteins with impacts between the 10thand 90th-percentile impacts of existing production. In addition to the reduction in food’s annual
GHG emissions, the land no longer required forfood production could remove ~8.1 billion metric
Poore et al., Science 360, 987–992 (2018)

1 June 2018

tons of CO2 from the atmosphere each year over
100 years as natural vegetation reestablishes andsoil carbon re-accumulates, based on simulations
conducted in the IMAGE integrated assessment
model (17). For the United States, where per capita
meat consumption is three times the global average, dietary change has the potential for a far
greater effect on food’s different emissions, reducing them by 61 to 73% [see supplementary text (17)for diet compositions and sensitivity analyses
and fig. S14 for alternative scenarios].
Consumers can play another important role byavoiding high-impact producers. We consider asecond scenario where consumption of each animal product is halved by replacing production
with above-median GHG emissions with vegetable equivalents. This achieves 71% of the previous
scenario’s GHG reduction (a reduction of ~10.4
billion metric tons of CO2 eq per year, including
atmospheric CO2 removal by regrowing vegetation) and 67, 64, and 55% of the land use, acidification, and eutrophication reductions. Further,lowering consumption of more discretionary
products (oils, sugar, alcohol, and stimulants)
by 20% by avoiding production with the highest
land use reduces the land use of these productsby 39% on average. For emissions, the reductions
are 31 to 46%, and for scarcity-weighted freshwater withdrawals, 87%.
Communicating average product impacts to
consumers enables dietary change and shouldbe pursued. Though dietary change is realistic
for any individual, widespread behavioral change
will be hard to achieve in the narrow timeframe
remaining to limit global warming and prevent
further, irreversible biodiversity loss. Communicating producer impacts allows access to thesecond scenario, which multiplies the effects ofsmaller consumer changes.
An integrated mitigation framework
In Fig. 4 we illustrate a potential framework implied by our findings, prior research, and emerging policy (9). First, producers would monitor
their impacts using digital tools (36). Data would
be validated against known ranges for each value(e.g., maximum yields given inputs) and validated

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animal and vegetable proteins will hold into the
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or certified independently. In the United Statesthese tools have already been integrated with existing farm software (31); in Africa and South Asia
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or by reallocating agricultural subsidies that now
exceed half a trillion dollars a year worldwide(38). Third, the assessment tools would provide
multiple mitigation and productivity enhancement
options to producers. Ideally these tools would become platforms that consolidate the vast amountsof research conducted by scientists around theworld, while also sharing producer best practices.
In particular, practice sharing offers a very effective way to engage producers (24). Maximum
flexibility also ensures least-cost mitigation (39)and supports producer-led innovation (24).
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traceability is already required in many countries(40), suggesting that communicating impacts ismost feasible where it matters the most. Communication could occur through a combination of environmental labels, taxes or subsidies designed toreflect environmental costs in product prices (35),and broader education on the true cost of food.
We have consolidated information on the practices and impacts of a wide range of producers.
From this research, we have provided a unified
exposition of the environmental science for making major changes to the food system. We hope
this stimulates progress in this crucially important area.

Erratum 22 February 2019. See Erratum.
R ES E A RC H | R E S EA R C H A R T I C LE

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ACKN OWLED GMEN TS

We thank the many researchers who provided us with additionaldata, acknowledged in data S1. We are grateful to R. Grenyer,
P. Smith, E. J. Milner-Gulland, C. Godfray, G. Gaillard, L. de Baan,
Y. Malhi, D. Thomas, K. Javanaud, and K. Afemikhe for commentson the manuscript and Tyana for illustrations. Funding: This work
was unfunded. Author contributions: J.P. conducted the analysis
and wrote the manuscript. J.P. and T.N. contributed to the study
design and data interpretation and reviewed the manuscript.
Competing interests: The authors declare no competing interests.
Data and materials availability: A Microsoft Excel file allowing full
replication of this analysis, containing all original and recalculateddata, has been deposited in the Oxford University Research Archive(doi.org/10.5287/bodleian:0z9MYbMyZ).
SUPPLEMENTARY MATERIALS

www.sciencemag.org/content/360/6392/987/suppl/DC1
Materials and Methods
Supplementary Text
Figs. S1 to S14
Tables S1 to S17
References (41–151)
Data S1 and S2
5 October 2017; resubmitted 8 December 2017
Accepted 17 April 201810.1126/science.aaq0216

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Poore et al., Science 360, 987–992 (2018)

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Reducing food's environmental impacts through producers and consumers
J. Poore and T. Nemecek

Science 360 (6392), 987-992.
DOI: 10.1126/science.aaq0216originally published online May 31, 2018

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The global impacts of food production
Food is produced and processed by millions of farmers and intermediaries globally, with substantial associatedenvironmental costs. Given the heterogeneity of producers, what is the best way to reduce food's environmental
impacts? Poore and Nemecek consolidated data on the multiple environmental impacts of ∼38,000 farms producing 40
different agricultural goods around the world in a meta-analysis comparing various types of food production systems. The
environmental cost of producing the same goods can be highly variable. However, this heterogeneity creates
opportunities to target the small numbers of producers that have the most impact.
Science, this issue p. 987