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Solutions for a Cultivated Planet

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  • University of Alabama Global Water Security Center

Abstract and Figures

Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world's future food security and sustainability needs, food production must grow substantially while, at the same time, agriculture's environmental footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress could be made by halting agricultural expansion, closing 'yield gaps' on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly reducing the environmental impacts of agriculture.
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ANALYSIS doi:10.1038/nature10452
Solutions for a cultivated planet
Jonathan A. Foley
1
, Navin Ramankutty
2
, Kate A. Brauman
1
, Emily S. Cassidy
1
, James S. Gerber
1
, Matt Johnston
1
,
Nathaniel D. Mueller
1
, Christine O’Connell
1
, Deepak K. Ray
1
, Paul C. West
1
, Christian Balzer
3
, Elena M. Bennett
4
,
Stephen R. Carpenter
5
, Jason Hill
1,6
, Chad Monfreda
7
, Stephen Polasky
1,8
, Johan Rockstro
¨m
9
, John Sheehan
1
, Stefan Siebert
10
,
David Tilman
1,11
& David P. M. Zaks
12
Increasing population and consumption are placing unprecedented demands on agriculture and natural resources.
Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently
degrading land, water, biodiversity and climate on a global scale. To meet the world’s future food security and
sustainability needs, food production must grow substantially while, at the same time, agriculture’s environmental
footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress
could be made by halting agricultural expansion, closing ‘yield gaps’ on underperforming lands, increasing cropping
efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly
reducing the environmental impacts of agriculture.
Contemporary agriculture faces enormous challenges
1–3
. Even
with recent productivity gains, roughly one in seven people lack
access to food or are chronically malnourished, stemming from
continued poverty and mounting food prices
4,5
. Unfortunately, the situ-
ation may worsen as food prices experience shocks from market specu-
lation, bioenergy crop expansion and climatic disturbances
6,7
. Even if we
solve these food access challenges, much more crop production will
probably be needed to guarantee future food security. Recent studies
suggest that production would need to roughly double to keep pace with
projected demands from population growth, dietary changes (especially
meat consumption), and increasing bioenergy use
1–4,8,9
, unless there are
dramatic changes in agricultural consumption patterns.
Compounding this challenge, agriculture must also address tremend-
ous environmental concerns. Agriculture is now a dominant force
behind many environmental threats, including climate change, biodi-
versity loss and degradation of land and freshwater
10–12
. In fact, agricul-
ture is a major force driving the environment beyond the ‘‘planetary
boundaries’’ of ref. 13.
Looking forward, we face one of the greatest challenges of the twenty-
first century: meeting society’s growing food needs while simultaneously
reducing agriculture’s environmental harm. Here we consider several
promising solutions to this grand challenge. Using new geospatial data
and models, we evaluate how new approaches to agriculture could bene-
fit both food production and environmental sustainability. Our analysis
focuses on the agronomic and environmental aspects of these chal-
lenges, and leaves a richer discussion of associated social, economic
and cultural issues to future work.
The state of global agriculture
Until recently, the scientific community could not measure, monitor and
analyse the agriculture–food–environment system’s complex linkages at
the global scale. Today, however, we have new data that characterize
worldwide patterns and trends in agriculture and the environment
14–17
.
Agricultural extent
According to the Food and Agriculture Organization (FAO) of the
United Nations, croplands cover 1.53 billion hectares (about 12% of
Earth’s ice-free land), while pastures cover another 3.38 billion hectares
(about 26% of Earth’s ice-free land) (Supplementary Fig. 1). Altogether,
agriculture occupies about 38% of Earth’s terrestrial surface—the largest
use of land on the planet
14,18
. These areas comprise the land best suited
for farming
19
: much of the rest is covered by deserts, mountains, tundra,
cities, ecological reserves and other lands unsuitable for agriculture
20
.
Between 1985 and 2005 the world’s croplands and pastures expanded
by 154 million hectares (about 3%). But this slow net increase includes
significant expansionin some areas (the tropics), as well as little change or
a decrease in others (the temperate zone
18
; Supplementary Table 1). The
result is a net redistribution of agricultural land towards the tropics, with
implications for food production, food security and the environment.
Crop yields
Global crop production has increased substantially in recent decades.
Studies of common crop groups (including cereals, oilseeds, fruits and
vegetables) suggest that crop production increased by 47% between 1985
and 2005 (ref. 18). However, considering all 174 crops tracked by the UN
FAO and ref. 15, we find global crop production increased by only 28%
during that time
18
.
This 28% gain in production occurred as cropland area increased by
only 2.4%, suggesting a 25% increase in yield. However, cropland area that
was harvested increased by about 7% between 1985 and 2005—nearly
three times the change in cropland area, owing to increased multiple
cropping, fewer crop failures, and less land left fallow. Accounting for
the increase in harvested land, average global crop yields increased by only
20% between 1985 and 2005, substantially less than the often-cited 47%
production increase for selected crop groups. (Usingthe same methods as
for the 20% result, we note that yields increased by 56% between 1965 and
1985, indicating that yields are now rising less quickly than before.)
1
Institute on the Environment (IonE), University of Minnesota, 1954 Buford Avenue, Saint Paul, Minnesota 55108, USA.
2
Department of Geography and Global Environmental and Climate Change Centre,
McGill University, 805 Sherbrooke Street, West Montreal, Quebec H3A 2K6, Canada.
3
Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California 93106, USA.
4
School of Environment and Department of Natural Resource Sciences, McGill University, 111 Lakeshore Road, Ste Anne de Bellevue, Quebec H9X 3V9, Canada.
5
Center for Limnology, University of
Wisconsin, 680 North Park Street, Madison, Wisconsin 53706, USA.
6
Department of Bioproducts and Biosystems Engineering, University of Minnesota, 2004 Folwell Avenue, Minnesota 55108, USA.
7
Consortium for Science, Policy and Outcomes (CSPO), Arizona State University, 1120 S Cady Mall, Tempe, Arizona 85287, USA.
8
Department of Applied Economics, University of Minnesota, 1994 Buford
Avenue, Minnesota 55108, USA.
9
Stockholm Resilience Centre, Stockholm University, SE-106 91, Stockholm, Sweden.
10
Institute of Crop Science and Resource Conservation, University of Bonn,
Katzenburgweg 5, D53115, Bonn, Germany.
11
Department of Ecology, Evolution & Behavior, University of Minnesota, 1987 Upper Buford Circle, Minnesota 55108, USA.
12
Center for Sustainability and the
Global Environment (SAGE), University of Wisconsin, 1710 University Avenue, Madison, Wisconsin 53726, USA.
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Aggregate measures of production can mask trends in individual
crops or crop groups (Supplementary Fig. 2a). For example, cereal crops
decreased in harvested area by 3.6% between 1985 and 2005, yet their
total production increased by 29%, reflecting a 34% increase in yields per
hectare. Oil crops, on the other hand, showed large increases in both
harvested area (43%) and yield (57%), resulting in a 125% increase in
total production
18
. While most crops increased production between
1985 and 2005, fodder crops did not: on average, they saw an 18%
production drop as a 26% loss in harvested area overrode an 11%
increase in yields.
Using geospatial data
15
, we can examine how yield patterns have
changed for key commodities (for example, maize in Supplementary
Fig. 2b). These geographic patterns show us where productivity gains
have been successful, where they have not, and where further oppor-
tunities for improvement lie.
Crop use and allocation
The allocation of crops to nonfood uses, including animal feed, seed,
bioenergy and other industrial products, affects the amount of food
available to the world. Globally, only 62% of crop production (on a mass
basis) is allocated to human food, versus 35% to animal feed (which
produces human food indirectly, and much less efficiently, as meat and
dairy products) and 3% for bioenergy, seed and other industrial products.
A striking disparity exists between regions that primarily grow crops
for direct human consumption and those that produce crops for other
uses (Fig. 1). North America and Europe devote only about 40% of their
croplands to direct food production, whereas Africa and Asia allocate
typically over 80% of their cropland to food crops. Extremes range from
the Upper Midwestern USA (less than 25%) to South Asia (over 90%).
As we face the twin challenges of feeding a growing world while
charting a more environmentally sustainable path, the amount of land
(and other resources) devoted to animal-based agriculture merits critical
evaluation. For example, adding croplands devoted to animal feed
(about 350 million hectares) to pasture and grazing lands (3.38 billion
hectares), we find the land devoted to raising animals totals 3.73 billion
hectares—an astonishing ,75% of the world’s agricultural land. We
further note that meat and dairy production can either add to or subtract
from the world’s food supply. Grazing systems, especially on pastures
unsuitable for other food production, and mixed crop–livestock systems
can add calories and protein to the world and improve economic con-
ditions and food security in many regions. However, using highly pro-
ductive croplands to produce animal feed, no matter how efficiently,
represents a net drain on the world’s potential food supply.
Global environmental impacts of agriculture
The environmental impacts of agriculture include those caused by
expansion (when croplands and pastures extend into new areas, repla-
cing natural ecosystems) and those caused by intensification (when
existing lands are managed to be more productive, often through the
use of irrigation, fertilizers, biocides and mechanization). Below, we use
new data and models
17,21,22
to examine both.
Agricultural expansion has had tremendous impacts on habitats, bio-
diversity, carbon storage and soil conditions
10,11,23,24
. In fact, worldwide
agriculture has already cleared or converted 70% of the grassland, 50% of
the savanna, 45% of the temperate deciduous forest, and 27% of the
tropical forest biome
14,25
.
Today, agriculture is mainly expanding in the tropics, where it is
estimated that about 80% of new croplands are replacing forests
26
. This
expansion is worrisome, given that tropical forests are rich reservoirs of
biodiversity and key ecosystem services
27
. Clearing tropical forests is also
a major source of greenhouse gas emissions and is estimated to release
around 1.1 310
15
grams of carbon per year, or about 12% of totalanthro-
pogenic CO
2
emissions
28
. Slowing or halting expansion of agriculture in
the tropics—which accounts for 98% of total CO
2
emissions from land
clearing
29
—will reduce carbon emissions as well as losses of biodiversity
and ecosystem services
27
.
Agricultural intensification has dramatically increased in recent decades,
outstripping rates of agricultural expansion, and has been responsible for
most of the yield increases of the past few decades. In the past 50 years, the
world’s irrigated cropland area roughly doubled
18,30,31
, while global fertilizer
use increased by 500% (over 800% for nitrogen alone)
18,32,33
. Intensification
has also caused water degradation, increased energy use, and widespread
pollution
32,34,35
.
Of particular concern is that some 70% of global freshwater with-
drawals (80–90% of consumptive uses) are devoted to irrigation
36,37
.
Furthermore, rain-fed agriculture is the world’s largest user of water
13,38
.
In addition, fertilizer use, manure application, and leguminous crops
(which fix nitrogen in the soil) have dramatically disrupted global nitro-
gen and phosphorus cycles
39–41
, with associated impacts on water quality,
aquatic ecosystems and marine fisheries
35,42
.
Both agricultural expansion and intensification are also major con-
tributors to climate change. Agriculture is responsible for 30–35% of
global greenhouse gas emissions, largely from tropical deforestation,
methane emissions from livestock and rice cultivation, and nitrous
oxide emissions from fertilized soils
29,43–46
.
We can draw important conclusions from these trends. First, the
expansion of agriculture in the tropics is reducing biodiversity, increas-
ing greenhouse gas emissions, and depleting critical ecosystem services.
Yet this expansion has done relatively little to add to global food sup-
plies; most production gains have been achieved through intensification.
Second, the costs and benefits of agricultural intensification vary greatly,
often depending on geographic conditions and agronomic practices.
This suggests that some forms (and locations) of intensification are
better than others at balancing food production and environmental
protection
11,47
.
Enhancing food production and sustainability
Until recently, most agricultural paradigms have focused on improving
production, often to the detriment of the environment
10,11,47
. Likewise,
many environmental conservation strategies have not sought to
improve food production. However, to achieve global food security
and environmental sustainability, agricultural systems must be trans-
formed to address both challenges (Fig. 2).
Food production area as fraction of total cropland
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Figure 1
|
Allocation of cropland area to different uses in 2000. Here we
show the fraction of the world’stotal cropland that is dedicated to growing food
crops (crops that are directly consumed by people) versus all other crop uses,
including animal feed, fibre, bioenergy crops and other products. Averaged
across the globe, 62% of total crop production (on a mass basis) is allocated to
human food, 35% for animal feed (which produces human food indirectly, and
less efficiently, as meat and dairy products) and 3% for bioenergy crops, seed,
and other industrial products. There are striking disparities between regions
that primarily grow crops for human consumption (such as Africa, South Asia,
East Asia), and those that mainly produce crops for other uses (such as North
America, Europe, Australia). Food production and allocation data were
obtained from FAOSTAT
18
, and were then applied to the spatialcropland maps
of refs 14 and 15. All data are for a seven-year period centred on 2000.
RESEARCH ANALYSIS
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First, the transformation of agriculture must deliver sufficient food
and nutrition to the world. To meet the projected demands of popu-
lation growth and increasing consumption, we must roughly double
food supplies in the next few decades
1–3
. We must also improve distri-
bution and access, which will require further changes in the food system.
The transformation of agriculture should also (1) cut greenhouse gas
emissions from land use and farming by at least 80% (ref. 48); (2) reduce
biodiversity and habitat losses; (3) reduce unsustainable water withdra-
wals, especially where water has competing demands; and (4) phase out
water pollution from agricultural chemicals. Other environmental issues
must also be addressed, but these four undergird the relationship
between agriculture and the environment and should be addressed as
necessary first steps.
An influential series of recent reports has suggested possible solutions
to our interwoven food security and environmental challenges
1,2,6
.
Below, we consider the potential strengths and weaknesses of four pro-
posed strategies.
Stop expanding agriculture
The expansion of agriculture into sensitive ecosystems has far-reaching
effects on biodiversity, carbon storage and important environmental
services
10,11,33
. This is particularly true when tropical forests are cleared
for agriculture
27,49,50
, estimated to cause 5–10 million hectares of forest
loss annually
18,51
. Slowing (and, ultimately, ceasing) the expansion of
agriculture, particularly into tropical forests, will be an important first
step in shifting agriculture onto a more sustainable path.
But will ending the expansion of agriculture negatively affect food
supplies? Our analysis suggests that the food production benefits of
tropical deforestation are often limited, especially compared to the
environmental damages accrued. First of all, many regions cleared for
agriculture in the tropics have low yields compared with their temperate
counterparts. The authors of ref. 21 considered crop production and
carbon emissions resulting from deforestation and demonstrated that
the balance of production gains to carbon losses was often poor in
tropical landscapes (Supplementary Fig. 3). Regions of tropical agricul-
ture that do have high yields—particularly areas of sugarcane, oil palm
and soybeans—typically do not contribute much to the world’s total
calorie or protein supplies, especially when crops are used for feed or
biofuels. Nevertheless, such crops do provide income, and thereby con-
tribute to poverty alleviation and food security to some sectors of the
population.
Although ceasing the expansion of agriculture into tropical forests
might have a negative—but probably small—impact on global crop pro-
duction, losses can be offset elsewhere in the food system. Agricultural
production potential that is ‘lost’ by halting deforestation could be offset
by reducing losses of productive farmland and improving yields on exist-
ing croplands. Though the ‘indirect land use’ effects of biofuel production
are thought to increase pressure on tropical forests
52
, it may also be true
that increasing food production in non-tropical zones might reduce
pressures on tropical forests.
Economic drivers hold great sway over deforestation
53–55
. Ecologically
friendly economic incentives could play an important part in slowing
forest loss: the proposed Reducing Emissions from Deforestation and
Degradation (REDD) programme, market certification, and ecotourism
all provide opportunities to benefit economically from forest protection
56
.
Close yield gaps
Increasing food production without agricultural expansion implies that
we must increase production on our existing agricultural lands. The best
places to improve crop yields may be on underperforming landscapes,
where yields are currently below average.
Recent analyses
57,58
have found large yield variations across the world,
even among regions with similar growing conditions, suggesting the
existence of ‘yield gaps’ (Supplementary Fig. 4a). Here we define a yield
gap as the difference between crop yields observed at any given location
and the crop’s potential yield at the same location given current agri-
cultural practices and technologies.
Much of the world experiences yield gaps (Supplementary Fig. 4a)
where productivity may be limited by management. There are significant
opportunities to increase yields across many parts of Africa, Latin
America and Eastern Europe, where nutrient and water limitations seem
to be strongest (Supplementary Fig. 4b). Better deployment of existing
crop varieties with improved management should be able to close many
yield gaps
59
, while continued improvements in crop genetics will probably
increase potential yields into the future.
Closing yield gaps could substantially increase global food supplies.
Our analysis shows that bringing yields to within 95% of their potential
for 16 important food and feed crops could add 2.3 billion tonnes
(5 310
15
kilocalories) of new production, a 58% increase (Fig. 3).
Even if yields for these 16 crops were brought up to only 75% of their
potential, global production would increase by 1.1 billion tonnes
(2.8 310
15
kilocalories), a 28% increase. Additional gains inproductivity,
focused on increasing the maximum yield of key crops, are likely to be
driven by genetic improvements
60,61
. Significant opportunities may also
exist to improve yield and the resilience of cropping systems by improving
‘orphan crops’ (such crops have not been genetically improved or had
much investment) and preserving crop diversity, which have received
relatively little investment to date.
To close global yield gaps, the interwoven challenges of production and
environment must again be addressed: conventional approaches to inten-
sive agriculture, especially the unbridled use of irrigation and fertilizers,
have been major causes of environmental degradation. Closing yield gaps
without environmental degradation will require new approaches, includ-
ing reforming conventional agriculture and adopting lessons from organic
systems and precision agriculture. In addition, closing yield gaps will
Total agricultural production
Real food production
Food security goals
Environmental goals
Food distribution and access
Resilience of food system
Greenhouse gas
emissions
Biodiversity loss
Unsustainable water
withdrawals
Water pollution
Minimum goals for 2050
Total agricultural production
Real food production
Food security goals
Environmental goals
Food distribution and access
Resilience of food system
Greenhouse gas emissions
Biodiversity loss Unsustainable water withdrawals
Water pollution
n
R
W
F
U
Minimum goals for 2050
a
b
Figure 2
|
Meeting goals for food security and environmental sustainability
by 2050. Here we qualitatively illustrate a subset of the goals agriculture must
meet in the coming decades. Atthe top, we outline four key food security goals:
increasing total agricultural production, increasing the supply of food
(recognizing that agricultural yields are not always equivalent to food),
improving the distribution of and access to food, andincreasing the resilience of
the whole foodsystem. At the bottom, we illustrate four keyenvironmental goals
agriculture must also meet: reducing greenhouse gas emissions from agriculture
and land use, reducing biodiversity loss, phasing out unsustainable water
withdrawals, and curtailing air and water pollution from agriculture. Panel
asketches out a qualitative assessment of how current agricultural systems may
be measured against these criteria compared to goals set for 2050. Panel
billustrates a hypothetical situation in which we meet all of these goals by 2050.
ANALYSIS RESEARCH
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require overcoming considerable economic and social challenges, includ-
ing the distribution of agricultural inputs and seedvarieties and improving
market infrastructure.
Increase agricultural resource efficiency
Moving forward, we must find more sustainable pathways for intensi-
fication that increase crop production while greatly reducing unsustain-
able uses of water, nutrients and agricultural chemicals.
Irrigation is currently responsible for water withdrawals of about
2,800 km
3
per year from groundwater, lakes and rivers. Irrigation is used
on about 24% of croplands and is responsible for delivering 34% of
agricultural production
17
. In fact, without irrigation, global cereal pro-
duction would decrease by an estimated 20% (ref. 17), so more land
would be required to produce the same amount of food.
However, the benefits and impacts of irrigation are not evenly dis-
tributed. Water needed for crop production varies greatly across the
world (Supplementary Fig. 5). We find that, when irrigated, 16 staple
crops use an average of 0.3 litres per kilocalorie (not including water
losses). However, these water requirements are skewed: 80% of irrigated
crops require less than 0.4 litres per kilocalorie, while the remaining 20%
require 0.7 litres per kilocalorie or more.
Where water is scarce, good water and land management practices
can increase irrigation efficiency. For example, curtailing off-field evap-
orative losses from water storage and transport and reducing on-field
losses through mulching and reduced tillage will increase the value of
irrigation water.
Chemical fertilizers, manure and leguminous crops have also been key
to agricultural intensification. However, they have also led to widespread
nutrient pollution and the degradation of lakes,rivers and coastal oceans.
In addition, the release of nitrous oxide from fertilized fields contributes
to climate change. Excess nutrients also incur energy costs associated
with converting atmospheric nitrogen and mining phosphorus
22,62
.
Even though excess nutrients cause environmental problems in some
parts of the world, insufficient nutrients are a major agronomic problem
in others. Many yield gaps are mainly due to insufficient nutrient avail-
ability (Supplementary Fig. 4b). This ‘Goldilocks’ problem of nutrients
(that is, there are many regions with too much or too little fertilizer but
few that are ‘just right’) is one of the key issues facing agriculture today
63
.
Building on recent analyses of crop production, fertilizer use and
nutrient cycling
15,22,64,65
, we examine patterns of agricultural nitrogen
and phosphorus balance across the world. Specifically, we show areas
of excess nutrients resulting from imbalances between nutrient inputs
(fertilizers, legumes and atmospheric deposition), harvest removal and
environmental losses (Supplementary Fig. 6). We further analyse the
efficiency of nutrient use by comparing applied nutrients to yield for 16
major crops (Supplementary Fig. 6c, d).
Our analysis reveals ‘hotspots’ of low nutrient use efficiency (Sup-
plementary Fig. 6c, d) and large volumes of excess nutrients (Sup-
plementary Fig. 6e, f). Nutrient excesses are especially large in
China
66
, Northern India, the USA and Western Europe. We also find
that only 10% of the world’s croplands account for 32% of the global
nitrogen surplus and 40% of the phosphorus surplus. Targeted policy
and management in these regions could improve the balance between
yields and the environment. Such actions include reducing excessive
fertilizer use, improving manure management, and capturing excess
nutrients through recycling, wetland restoration and other practices.
Taken together, these results illustrate many opportunities to improve
the water and nutrient efficiency of agriculture without reducing food
production. Targeting particular ‘hotspots’ of low efficiency, measured
as the disproportionate use of water and nutrient inputs relative to
production, could significantly reduce the environmental problems of
intensive agriculture. Furthermore, agroecological innovations in crop
and soil management
1,67
show great promise for improving the resource
efficiency of agriculture, maintaining the benefits of intensive agricul-
ture while greatly reducing harm to the environment.
Increase food delivery by shifting diets and reducing waste
While improving crop yields and reducing agriculture’s environmental
impacts will be instrumental in meeting future needs, it is also important
to remember that more food can be delivered by changing our agricul-
tural and dietary preferences. Simply put, we can increase food avail-
ability (in terms of calories, protein and critical nutrients) by shifting
crop production away from livestock feed, bioenergy crops and other
non-food applications.
In Supplementary Fig. 7, we compare intrinsic food production (calories
available if all crops were consumed by humans) and delivered food pro-
duction (calories available based on today’s allocation of crops to food,
animal feed, and other products, assuming standard conversion factors) for
16 staple crops. By subtracting these two figures, we estimate the potential
to increase food supplies by closing the ‘diet gap’: shifting 16 major crops to
100% human food could add over a billion tonnes to global food produc-
tion (a 28% increase), or the equivalent of 3 310
15
food kilocalories (a 49%
increase) (Fig. 4).
Of course, the current allocation of crops has many economic and
social benefits, and this mixed use is not likely to change completely. But
even small changes in diet (for example, shifting grain-fed beef con-
sumption to poultry, pork or pasture-fed beef) and bioenergy policy (for
example, not using food crops as biofuel feedstocks) could enhance food
availability and reduce the environmental impacts of agriculture.
A large volume of food is never consumed but is instead discarded,
degraded or consumed by pests along the supply chain. A recent FAO
study
68
suggests that about one-third of food is never consumed; others
69
have suggested that as much as half of all food grown is lost; and some
perishable commodities have post-harvest losses of up to 100% (ref. 70).
Developing countries lose more than 40% of food post-harvest or during
processing because of storage and transport conditions. Industrialized
countries have lower producer losses, but at the retail or consumer level
more than 40% of food may be wasted
68
.
In short, reducing food waste and rethinking dietary, bioenergy and
other agricultural choices could substantially improve the delivery of
calories and nutrition with no accompanying environmental harm.
While wholesale conversions of the human diet and the elimination of
New calories from closing yield gaps for staple crops
(×106 kcal per hectare)
0 0.5 1 1.5 2 2 .5 3 3.5 4 4 .5 5
Figure 3
|
Closing global yield gaps. Many agricultural lands do not attain
their full yield potential. The figure shows the new calories that would be made
available to the world from closing the yield gaps for 16 major crops: barley,
cassava, groundnut,maize, millet, potato, oil palm,rapeseed, rice, rye, sorghum,
soybean, sugarbeet, sugarcane, sunflower and wheat. This analysis shows that
bringing the world’s yields to within 95% of their potential for these 16
important food and feed crops could add 2.3 billion tonnes
(5 310
15
kilocalories) of new crop production, representing a 58% increase.
These improvements in yield can be largely accomplished by improving the
nutrient and water supplies to crops in low-yielding regions; further
enhancement of global food production could be achieved through improved
crop genetics. The methods used to calculate yield gaps and limiting factors are
described in the Supplementary Information.
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food waste are not realistic goals, even incremental steps could be extre-
mely beneficial. Furthermore, targeted efforts—such as reducing waste
in our most resource-intensive foods, especially meat and dairy—could
be designed for optimal impact.
Searching for practical solutions
Today, humans are farming more of the planet than ever, with higher
resource intensity and staggering environmental impacts, while divert-
ing an increasing fraction of crops to animals, biofuels and other non-
food uses. Meanwhile, almost a billion people are chronically hungry.
This must not continue: the requirements of current and future genera-
tions demand that we transform agriculture to meet the twin challenges
of food security and environmental sustainability.
Our analysis demonstrates that four core strategies can—in principle—
meet future food production needs and environmental challenges if
deployedsimultaneously. Addingthem together, theyincrease global food
availability by 100–180%, meeting projected demands while lowering
greenhouse gas emissions, biodiversity losses, water use and water pol-
lution. However, all four strategies are needed to meet our global food
production and environmental goals; no single strategy is sufficient.
We have described general approaches to solving global agricultural
challenges, but much work remains to translate them into action.
Specific land use, agricultural and food system tactics must be developed
and deployed. Fortunately, many such tactics already exist, including
precision agriculture, drip irrigation, organic soil remedies, buffer strips
and wetland restoration, new crop varieties that reduce needs for water
and fertilizer, perennial grains and tree-cropping systems, and paying
farmers for environmental services. However, deploying these tactics
effectively around the world requires numerous economic and govern-
ance challenges to be overcome. For example, reforming global trade
policies, including eliminating price-distorting subsidies and tariffs, will
be vital to achieving our strategies.
In developing improved land use and agricultural practices, we
recommend following these guidelines:
(1) Solutions should focus on critical biophysical and economic ‘lever-
age points’ in agricultural systems, where major improvements in food
production or environmental performance may be achieved with the
least effort and cost.
(2) New practices must also increase the resilience of the food system.
High-efficiency, industrialized agriculture has many benefits, but it is
vulnerable to disasters
71
, including climatic disturbances, new diseases
and economic calamities.
(3) Agricultural activities have many costs and benefits, but methods of
evaluating the trade-offs are still poorly developed
72
. We need better
data and decision support tools to improve management decisions
73
,
productivity and environmental stewardship.
(4) The search for agricultural solutions should remain technology-
neutral. There are multiple paths to improving the production, food
security and environmental performance of agriculture, and we should
not be locked into a single approach a priori, whether it be conventional
agriculture, genetic modification or organic farming.
The challenges facing agriculture today are unlike anything we have
experienced before, and they require revolutionary approaches to solv-
ing food production and sustainability problems. In short, new agricul-
tural systems must deliver more human value, to those who need it most,
with the least environmental harm.
Published online 12 October 2011.
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Potential diet gap calories
(×106 kcal per hectare)
0 0.5 1 1.5 2 2.5 3 3.5 44.5 5
Figure 4
|
Closing the diet gap. We estimate the potential to increase food
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Supplementary Information is linked to the online version of the paper at
www.nature.com/nature.
Acknowledgements We are grateful for the support of NASAand the National Science
Foundation. We also acknowledge the support of the Stockholm Resilience Centre, for
conveninga workshop on meeting globalagricultural demandswhile staying within the
‘planetary limits’. We thank C. Godfray and C. Prentice for comments on the
manuscript. We also thank M. Hoff and S. Karnas for help with the manuscript and
figures.
Author Contributions J.A.F., N.R., K.A.B., E.S.C., J.S.G., M.J., N.D.M., C.O’C., D.K.R. and
P.C.W. conducted most of the data production, analysis and shared writing
responsibilities. C.B.,C.M., S.S. and D.T. contributeddata and shared in the scopingand
writing responsibilities. E.M.B., S.R.C., J.H., S.P., J.R., J.S. and D.P.M.Z. shared in the
scoping and writing responsibilities.
Author Information Reprints and permissions information is available at
www.nature.com/reprints. The authors declare no competing financial interests.
Readers are welcome to comment on the online version of this article at
www.nature.com/nature. Correspondence and requests for materials should be
addressed to J.A.F. (jfoley@umn.edu).
RESEARCH ANALYSIS
6 | NATURE | VOL 000 | 00 MONTH 2011
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©2011
... Environmental concerns regarding livestock production are related to soil acidification, water eutrophication (pollution) [32,36,37], and GHG emissions [38][39][40]. For example, the excessive use of manure or mineral fertilizers can lead to the accumulation of nutrients in soils (contamination) and water pollution through runoff and leaching [41,42]. ...
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