Food Security: The Challenge of Feeding 9 Billion People

Abstract

Continuing population and consumption growth will mean that the global demand for food will increase for at least another 40 years. Growing competition for land, water, and energy, in addition to the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement to reduce the impact of the food system on the environment. The effects of climate change are a further threat. But the world can produce more food and can ensure that it is used more efficiently and equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food security, different components of which are explored here.

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DOI: 10.1126/science.1185383
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REVIEW
Food Security: The Challenge of
Feeding 9 Billion People
H. Charles J. Godfray,
1
*John R. Beddington,
2
Ian R. Crute,
3
Lawrence Haddad,
4
David Lawrence,
5
James F. Muir,
6
Jules Pretty,
7
Sherman Robinson,
8
Sandy M. Thomas,
9
Camilla Toulmin
10
Continuing population and consumption growth will mean that the global demand for food will
increase for at least another 40 years. Growing competition for land, water, and energy, in addition to
the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement
to reduce the impact of the food system on the environment. The effects of climate change are a
further threat. But the world can produce more food and can ensure that it is used more efficiently and
equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food
security, different components of which are explored here.
The past half-century has seen marked
growth in food production, allowing for a
dramatic decrease in the proportion of the
world’s people that are hungry, despite a doubling
of the total population (Fig. 1) (1,2). Neverthe-
less, more than one in seven people today still do
not have access to sufficient protein and energy
from their diet, and even more suffer from some
form of micronutrient malnourishment (3). The
world is now facing a new set of intersecting chal-
lenges (4). The global population will continue to
grow, yet it is likely to plateau at some 9 billion
people by roughly the middle of this century. A
major correlate of this deceleration in population
growth is increased wealth, and with higher pur-
chasing power comes higher consumption and a
greater demand for processed food, meat, dairy,
and fish, all of which add pressure to the food
supply system. At the same time, food producers
are experiencing greater competition for land,
water, and energy, and the need to curb the many
negative effects of food production on the envi-
ronment is becoming increasingly clear (5,6).
Overarching all of these issues is the threat of the
effects of substantial climate change and concerns
about how mitigation and adaptation measures
may affect the food system (7,8).
A threefold challenge now faces the world (9):
Match the rapidly changing demand for food
from a larger and more affluent population to its
supply; do so in ways that are environmentally
and socially sustainable; and ensure that the
world’s poorest people are no longer hungry.
This challenge requires changes in the way food
is produced, stored, processed, distributed, and
accessed that are as radical as those that occurred
during the 18th- and 19th-century Industrial and
Agricultural Revolutions and the 20th-century
Green Revolution. Increases in production will
have an important part to play, but they will be
constrained as never before by the finite resources
provided by Earth’s lands, oceans, and atmo-
sphere (10).
Patterns in global food prices are indicators of
trends in the availability of food, at least for those
who can afford it and have access to world mar-
kets. Over the past century, gross food prices have
generally fallen, leveling off in the past three dec-
ades but punctuated by price spikes such as that
caused by the 1970s oil crisis. In mid-2008, there
was an unexpected rapid rise in food prices, the
cause of which is still being debated, that subsided
when the world economy went into recession (11).
However, many (but not all) commentators have
predicted that this spike heralds a period of rising
and more volatile food prices driven primarily by
increased demand from rapidly developing coun-
tries, as well as by competition for resources from
first-generation biofuels production (12). Increased
food prices will stimulate greater investment in
food production, but the critical importance of food
to human well-being and also to social and po-
litical stability makes it likely that
governments and other organizations
will want to encourage food pro-
duction beyond that driven by sim-
ple market mechanisms (13). The
long-term nature of returns on in-
vestment for many aspects of food
production and the importance of
policies that promote sustainability
and equity also argue against purely
relying on market solutions.
So how can more food be pro-
duced sustainably? In the past, the
primary solution to food shortages
has been to bring more land into
agriculture and to exploit new fish
stocks. Yet over the past 5 decades,
while grain production has more
than doubled, the amount of land
devoted to arable agriculture global-
ly has increased by only ~9% (14).
Some new land could be brought
into cultivation, but the competi-
tion for land from other human ac-
tivities makes this an increasingly
unlikely and costly solution, par-
ticularly if protecting biodiversity
and the public goods provided by
natural ecosystems (for example,
carbon storage in rainforest) are
given higher priority (15). In recent
decades, agricultural land that was
formerly productive has been lost
to urbanization and other human
uses, as well as to desertification,
salinization, soil erosion, and other
consequences of unsustainable land
1
Department of Zoology and Institute of Biodiversity at the
James Martin 21st Century School, University of Oxford, South
Parks Road, Oxford OX1 3PS, UK.
2
U.K. Government Office for
Science, 1 Victoria Street, London SW1H OET, UK.
3
Agricul-
ture and Horticulture Development Board, Stoneleigh Park,
Kenilworth, Warwickshire CV8 2TL, UK.
4
Institute of Develop-
ment Studies, Falmer, Brighton BN1 9RE, UK.
5
Syngenta AG,
Post Office Box, CH-4002 Basel, Switzerland.
6
Institute of Aqua-
culture, University of Stirling, Stirling FK9 4LA, UK.
7
Department
of Biological Sciences, University of Essex, Wivenhoe Park,
Colchester, Essex CO4 3SQ, UK.
8
Institute of Development
Studies, Falmer, Brighton BN1 9RE, UK.
9
Foresight, U.K. Gov-
ernment Office for Science, 1 Victoria Street, London SW1H
OET, UK.
10
International Institute for Environment and Develop-
ment, 3 Endsleigh Street, London WC1H 0DD, UK.
*To whom correspondence should be addressed. E-mail:
charles.godfray@zoo.ox.ac.uk
1960
Relative productionRelative numbers
1970 1980 1990 2000 2010
3.5
3.0
2.5
2.0
1.5
1.0
0.5
Main grains (wheat, barley,
maize, rice, oats)
Coarse grains
(millet, sorghum)
Chickens
Pigs
Cattle and buffalo
Sheep and goats
Root crops
(cassava, potato)
1960 1970 1980 1990 2000 2010
3.5
4.5
3.0
4.0
5.0
2.5
2.0
1.5
1.0
0.5
A
B
Fig. 1. Changes in the relative global production of crops and
animals since 1961 (when relative production scaled to 1 in
1961). (A) Major crop plants and (B)majortypesoflivestock.
[Source: (2)]
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management (16). Further losses, which may
be exacerbated by climate change, are likely
(7). Recent policy decisions to produce first-
generation biofuels on good quality agricultural
land have added to the competitive pressures
(17). Thus, the most likely scenario is that more
food will need to be produced from the same
amount of (or even less) land. Moreover, there
are no major new fishing grounds: Virtually all
capture fisheries are fully exploited, and most
are overexploited.
Recent studies suggest that the world will
need 70 to 100% more food by 2050 (1,18). In
this article, major strategies
for contributing to the chal-
lenge of feeding 9 billion
people, including the most
disadvantaged, are explored.
Particular emphasis is given
to sustainability, as well as
to the combined role of the
natural and social sciences
in analyzing and addressing
the challenge.
Closing the Yield Gap
There is wide geographic var-
iation in crop and livestock
productivity, even across re-
gions that experience similar
climates. The difference be-
tween realized productivity
and the best that can be
achieved using current ge-
netic material and available
technologies and manage-
ment is termed the “yield
gap.”The best yields that
can be obtained locally depend on the capacity
of farmers to access and use, among other things,
seeds, water, nutrients, pest management, soils,
biodiversity, and knowledge. It has been esti-
mated that in those parts of Southeast Asia
where irrigation is available, average maximum
climate-adjusted rice yields are 8.5 metric tons
per hectare, yet the average actually achieved
yields are 60% of this figure (19). Similar yield
gaps are found in rain-fed wheat in central Asia
and rain-fed cereals in Argentina and Brazil.
Another way to illustrate the yield gap is to
compare changes in per capita food production
over the past 50 years. In Asia, this amount has
increased approximately twofold (in China, by a
factor of nearly 3.5), and in Latin America, it has
increased 1.6-fold; in Africa, per capita produc-
tion fell back from the mid-1970s and has only
just reached the same level as in 1961 (2,20).
Substantially more food, as well as the income to
purchase food, could be produced with current
crops and livestock if methods were found to
close the yield gaps.
Low yields occur because of technical con-
straints that prevent local food producers from
increasing productivity or for economic reasons
arising from market conditions. For example,
farmers may not have access to the technical
knowledge and skills required to increase pro-
duction, the finances required to invest in higher
production (e.g., irrigation, fertilizer, machinery,
crop-protection products, and soil-conservation
measures), or the crop and livestock varieties
that maximize yields. After harvest or slaughter,
they may not be able to store the produce or
have access to the infrastructure to transport the
produce to consumer markets. Farmers may also
choose not to invest in improving agricultural
productivity because the returns do not compare
well with other uses of capital and labor.
Exactly how best to facilitate increased food
production is highly site-specific. In the most
extreme cases of failed states and nonfunction-
ing markets, the solution lies completely out-
side the food system. Where a functioning state
exists, there is a balance to be struck between
investing in overall economic growth as a spur
to agriculture and focusing on investing in ag-
riculture as a spur to economic growth, though
the two are obviously linked in regions, such as
sub-Saharan Africa, where agriculture typically
makes up 20 to 40% gross domestic product.
In some situations, such as low-income food-
importing countries, investing purely in generat-
ing widespread income growth to allow food
purchases from regions and countries with bet-
ter production capabilities may be the best
choice. When investment is targeted at food
production, a further issue is the balance be-
tween putting resources into regional and na-
tional infrastructure, such as roads and ports,
and investing in local social and economic
capital (21,22).
A yield gap may also exist because the high
costs of inputs or the low returns from increased
production make it economically suboptimal to
raise production to the maximum technically at-
tainable. Poor transport and market infrastruc-
ture raise the prices of inputs, such as fertilizers
and water, and increase the costs of moving the
food produced into national or world markets.
Where the risks of investment are high and the
means to offset them are absent, not investing
can be the most rational decision, part of the
“poverty trap.”Food production in developing
countries can be severely affected by market
interventions in the developed
world, such as subsidies or price
supports. These need to be care-
fully designed and implemented
so that their effects on global
commodity prices do not act as
disincentives to production in
other countries (23).
The globalization of the
food system offers some local
food producers access to larger
markets, as well as to capital
for investment. At the aggre-
gate level, it also appears to
increase the global efficiency
of food production by allowing
regional specialization in the
production of the locally most
appropriate foods. Because the
expansion of food production
and the growth of population
both occur at different rates in
different geographic regions,
global trade is necessary to ba-
lance supply and demand across
regions. However, the environmental costs of
food production might increase with globaliza-
tion, for example, because of increased greenhouse
gas emissions associated with increased produc-
tion and food transport (24). An unfettered mar-
ket can also penalize particular communities and
sectors, especially the poorest who have the least
influence on how global markets are structured
and regulated. Expanded trade can provide insur-
ance against regional shocks on production such
as conflict, epidemics, droughts, or floods—shocks
that are likely to increase in frequency as climate
change occurs. Conversely, a highly connected
food system may lead to the more widespread
propagation of economic perturbations, as in the
recent banking crisis, thus affecting more peo-
ple. There is an urgent need for a better under-
standing of the effects of globalization on the
full food system and its externalities.
The yield gap is not static. Maintaining, let
alone increasing, productivity depends on con-
tinued innovation to control weeds, diseases, in-
sects, and other pests as they evolve resistance
to different control measures, or as new spe-
cies emerge or are dispersed to new regions.
Box 1. Sustainable intensification.
Producing more food from the same area of land while reducing the environmental
impacts requires what has been called “sustainable intensification”(18). In exactly the
same way that yields can be increased with the use of existing technologies, many
options currently exist to reduce negative externalities (47). Net reductions in some
greenhouse gas emissions can potentially be achieved by changing agronomic
practices, the adoption of integrated pest management methods, the integrated
management of waste in livestock production, and the use of agroforestry. However,
the effects of different agronomic practices on the full range of greenhouse gases can
be very complex and may depend on the temporal and spatial scale of measurement.
More research is required to allow a better assessment of competing policy options.
Strategies such as zero or reduced tillage (the reduction in inversion ploughing),
contour farming, mulches, and cover crops improve water and soil conservation, but
they may not increase stocks of soil carbon or reduce emissions of nitrous oxide.
Precision agriculture refers to a series of technologies that allow the application of
water, nutrients, and pesticides only to the places and at the times they are required,
thereby optimizing the use of inputs (48). Finally, agricultural land and water bodies
used for aquaculture and fisheries can be managed in ways specifically designed to
reduce negative impacts on biodiversity.
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Innovation involves both traditional and ad-
vanced crop and livestock breeding, as well as
the continuing development of better chemical,
agronomic, and agro-ecological control mea-
sures. The maximum attainable yield in different
regions will also shift as the effects of climate
change are felt. Increasing atmospheric CO
2
lev-
els can directly stimulate crop growth, though
within the context of real agricultural production
systems, the magnitude of this effect is not clear
(7). More important will be the ability to grow
crops in places that are currently unsuitable, par-
ticularly the northern temperate regions (though
expansion of agriculture at the expense of boreal
forest would lead to major greenhouse gas emis-
sions), and the loss of currently productive re-
gions because of excessively high temperatures
and drought. Models that couple the physics of
climate change with the biology of crop growth
will be important to help policy-makers antici-
pate these changes, as well as to evaluate the role
of “agricultural biodiversity”in helping mitigate
their effects (25).
Closing the yield gap would dramatically
increase the supply of food, but with uncertain
impacts on the environment and potential feed-
backs that could undermine future food produc-
tion. Food production has important negative
“externalities,”namely effects on the environment
or economy that are not reflected in the cost of
food. These include the release of greenhouse
gases [especially methane and nitrous oxide,
which are more damaging than CO
2
and for
which agriculture is a major source (26)], envi-
ronmental pollution due to nutrient run-off, water
shortages due to overextraction, soil degrada-
tion and the loss of biodiversity through land
conversion or inappropriate management, and
ecosystem disruption due to the intensive har-
vesting of fish and other aquatic foods (6).
To address these negative effects, it is now
widely recognized that food production systems
and the food chain in general must become fully
sustainable (18). The principle of sustainability
implies the use of resources at rates that do not
exceed the capacity of Earth to replace them.
By definition, dependency on nonrenewable
inputs is unsustainable, even if in the short
term it is necessary as part of a trajectory toward
sustainability.
There are many difficulties in making sustain-
ability operational. Over what spatial scale should
food production be sustainable? Clearly an over-
arching goal is global sustainability, but should
this goal also apply at lower levels, such as re-
gions (or oceans), nations, or farms? Could high
levels of consumption or negative externalities
in some regions be mitigated by improvements
in other areas, or could some unsustainable
activities in the food system be offset by actions
in the nonfood sector (through carbon-trading,
for example)? Though simple definitions of
sustainability are independent of time scale, in
practice, how fast should we seek to move from
the status quo to a sustainable food system? The
challenges of climate change and competition
for water, fossil fuels, and other resources suggest
that a rapid transition is essential. Nevertheless,
it is also legitimate to explore the possibility that
superior technologies may become available and
that future generations may be wealthier and,
hence, better able to absorb the costs of the tran-
sition. Finally, we do not yet have good enough
metrics of sustainability, a major problem when
evaluating alternative strategies and negotiat-
ing trade-offs. This is the case for relatively cir-
cumscribed activities, such as crop production
on individual farms, and even harder when the
complete food chain is included or for complex
products that may contain ingredients sourced
from all around the globe. There is also a danger
that an overemphasis on what can be measured
relatively simply (carbon, for example) may lead
to dimensions of sustainability that are harder
to quantify (such as biodiversity) being ignored.
These are areas at the interface of science, en-
gineering, and economics that urgently need more
attention (see Box 1). The introduction of mea-
sures to promote sustainability does not neces-
sarily reduce yields or profits. One study of 286
agricultural sustainability projects in developing
countries, involving 12.6 million chiefly small-
holder farmers on 37 million hectares, found an
average yield increase of 79% across a very wide
varietyofsystemsandcroptypes(27). One-quarter
of the projects reported a doubling of yield. Re-
search on the ability of these and related pro-
grams to be scaled up to country and regional
levels should be a priority (Fig. 2).
Strategies designed to close the yield gap in
the poorest countries face some particular chal-
lenges (28). Much production is dominated by
small-holder agriculture with women often taking
a dominant role in the workforce. Where viable,
investment in the social and economic mecha-
nisms to enable improved small-holder yields,
especially where targeted at women, can be im-
portant means of increasing the income of both
farm and rural nonfarm households. The lack of
secure land rights can be a particular problem for
many poor communities, may act as a disincen-
tive for small holders to invest in managing the
land more productively, and may make it harder
to raise investment capital (29). In a time of ris-
ing prices for food and land, it can also render
these communities vulnerable to displacement by
more powerful interest groups. Where the polit-
ical will and organizational infrastructure exist,
title definition and protection could be greatly
assisted by the application of modern informa-
tion and communication technologies. Even so,
there will be many people who cannot afford to
purchase sufficient calories and nutrients for a
healthy life and who will require social protection
programs to increase their ability to obtain food.
However, if properly designed, these programs
can help stimulate local agriculture by providing
small holders with increased certainty about the
demand for their products.
Fig. 2. An example of a major successful sustainable agriculture project. Niger was strongly affected by
a series of drought years in the 1970s and 1980s and by environmental degradation. From the early
1980s, donors invested substantially in soil and water conservation. The total area treated is on the
order of 300,000 ha, most of which went into the rehabilitation of degraded land. The project in the
Illela district of Niger promoted simple water-harvesting techniques. Contour stone bunds, half moons,
stone bunding, and improved traditional planting pits (zaı¨) were used to rehabilitate barren, crusted
land. More than 300,000 ha have been rehabilitated, and crop yields have increased and become more
stable from year to year. Tree cover has increased, as shown in the photographs. Development of the
land market and continued incremental expansion of the treated area without further project assistance
indicate that the outcomes are sustainable (51,52).
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There is also a role for large-scale farming
operations in poor-country agriculture, though the
value and contexts in which this is feasible are
much debated (30). This debate has been fanned
by a substantial increase in the number of sov-
ereign wealth funds, companies, and individuals
leasing, purchasing, or attempting to purchase
large tracts of agricultural land in developing
countries. This external investment in developing-
country agriculture may bring major benefits,
especially where investors bring considerable
improvements to crop production and process-
ing, but only if the rights and welfare of the
tenants and existing resource users are properly
addressed (31).
Many of the very poorest people live in areas
so remote that they are effectively disconnected
from national and world food markets. But for
others, especially the urban poor, higher food
prices have a direct negative effect on their ability
to purchase a healthy diet. Many rural farmers
and other food producers live near the margin of
being net food consumers and producers and will
be affected in complex ways by rising food prices,
with some benefitting and some being harmed
(21). Thus, whereas reducing distorting agricul-
tural support mechanisms in developed countries
and liberalizing world trade should stimulate
overallfoodproductionindevelopingcountries,
not everyone will gain (23,32). Better models
that can more accurately predict these complex
interactions are urgently needed.
Increasing Production Limits
The most productive crops, such as sugar cane,
growing in optimum conditions, can convert solar
energy into biomass with an efficiency of ~2%,
resultinginhighyieldsofbiomass(upto150
metric tons per hectare) (33). There is much de-
bate over exactly what the theoretical limits are
for the major crops under different conditions, and
similarly, for the maximum yield that can be ob-
tained for livestock rearing (18). However, there is
clearly considerable scope for increasing produc-
tion limits.
The Green Revolution succeeded by using
conventional breeding to develop F
1
hybrid vari-
eties of maize and semi-dwarf, disease-resistant
varieties of wheat and rice. These varieties could
be provided with more irrigation and fertilizer
(20) without the risk of major crop losses due to
lodging (falling over) or severe rust epidemics.
Increased yield is still a major goal, but the im-
portance of greater water- and nutrient-use effi-
ciency, as well as tolerance of abiotic stress, is
also likely to increase. Modern genetic techniques
and a better understanding of crop physiology al-
low for a more directed approach to selection
across multiple traits. The speed and costs at which
genomes today can be sequenced or resequenced
now means that these techniques can be more
easily applied to develop varieties of crop species
that will yield well in challenging environments.
These include crops such as sorghum, millet, cas-
sava, and banana, species that are staple foods for
many of the world’s poorest communities (34).
Currently, the major commercialized geneti-
cally modified (GM) crops involve relatively sim-
ple manipulations, such as the insertion of a gene
for herbicide resistance or another for a pest-insect
toxin. The next decade will see the development
of combinations of desirable traits and the intro-
duction of new traits such as drought tolerance.
By mid-century, much more radical options in-
volving highly polygenic traits may be feasible
(Table 1). Production of cloned animals with en-
gineered innate immunity to diseases that reduce
production efficiency has the potential to reduce
substantial losses arising from mortality and
subclinical infections. Biotechnology could also
produce plants for animal feed with modified
composition that increase the efficiency of meat
production and lower methane emissions.
Domestication inevitably means that only a
subset of the genes available in the wild-species
progenitor gene pool is represented among crop
varieties and livestock breeds. Unexploited ge-
netic material from land races, rare breeds, and
wild relatives will be important in allowing
breeders to respond to new challenges. Interna-
tional collections and gene banks provide val-
uable repositories for such genetic variation, but
it is nevertheless necessary to ensure that locally
adapted crop and livestock germplasm is not lost
in the process of their displacement by modern,
improved varieties and breeds. The trend over
recent decades is of a general decline in invest-
ment in technological innovation in food produc-
tion (with some notable exceptions, such as in
China and Brazil) and a switch from public to
private sources (1). Fair returns on investment are
essential for the proper functioning of the pri-
vate sector, but the extension of the protection
of intellectual property rights to biotechnology
has led to a growing public perception in some
countries that biotech research purely benefits
commercial interests and offers no long-term
public good. Just as seriously, it also led to a
virtual monopoly of GM traits in some parts of
the world, by a restricted number of companies,
which limits innovation and investment in the
technology. Finding ways to incentivize wide ac-
cess and sustainability, while encouraging a com-
petitive and innovative private sector to make
best use of developing technology, is a major
governance challenge.
The issue of trust and public acceptance of
biotechnology has been highlighted by the debate
over the acceptance of GM technologies. Because
genetic modification involves germline modifi-
cation of an organism and its introduction to the
environment and food chain, a number of par-
ticular environmental and food safety issues need
to be assessed. Despite the introduction of rig-
orous science-based risk assessment, this discus-
sion has become highly politicized and polarized
in some countries, particularly those in Europe.
Our view is that genetic modification is a poten-
tially valuable technology whose advantages and
disadvantages need to be considered rigorously
on an evidential, inclusive, case-by-case basis:
Genetic modification should neither be privileged
nor automatically dismissed. We also accept the
Table 1. Examples of current and potential future applications of GM technology for crop genetic
improvement. [Source: (18,49)]
Time scale Target crop trait Target crops
Current Tolerance to broad-spectrum
herbicide
Maize, soybean, oilseed
brassica
Resistance to chewing insect
pests
Maize, cotton, oilseed
brassica
Short-term
(5–10 years)
Nutritional bio-fortification Staple cereal crops, sweet
potato
Resistance to fungus and virus
pathogens
Potato, wheat, rice, banana,
fruits, vegetables
Resistance to sucking insect pests Rice, fruits, vegetables
Improved processing and storage Wheat, potato, fruits,
vegetables
Drought tolerance Staple cereal and tuber crops
Medium-term
(10–20 years)
Salinity tolerance Staple cereal and tuber crops
Increased nitrogen-use
efficiency
High-temperature tolerance
Long-term
(>20 years)
apomixis Staple cereal and tuber crops
Nitrogen fixation
Denitrification inhibitor
production
Conversion to perennial habit
Increased photosynthetic efficiency
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need for this technology to gain greater public
acceptance and trust before it can be considered
as one among a set of technologies that may
contribute to improved global food security.
There are particular issues involving new
technologies, both GM and non-GM, that are
targeted at helping the least-developed countries
(35,36). The technologies must be directed at
the needs of those communities, which are often
different from those of more developed country
farmers. To increase the likelihood that new tech-
nology works for, and is adopted by, the poorest
nations, they need to be involved
in the framing, prioritization, risk
assessment, and regulation of inno-
vations. This will often require the
creation of innovative institutional
and governance mechanisms that ac-
count for socio-cultural context (for
example, the importance of women
in developing-country food produc-
tion). New technologies offer major
promise, but there are risks of lost
trust if their potential benefits are
exaggerated in public debate. Efforts
to increase sustainable production
limits that benefit the poorest nations
will need to be based around new
alliances of businesses, civil society
organizations, and governments.
Reducing Waste
Roughly 30 to 40% of food in both
the developed and developing worlds
is lost to waste, though the causes
behind this are very different (Fig. 3)
(16,37–39). In the developing world,
losses are mainly attributable to the absence of
food-chain infrastructure and the lack of knowl-
edge or investment in storage technologies on
the farm, although data are scarce. For example,
in India, it is estimated that 35 to 40% of fresh
produce is lost because neither wholesale nor
retail outlets have cold storage (16). Even with
rice grain, which can be stored more readily, as
much as one-third of the harvest in Southeast
Asia can be lost after harvest to pests and spoil-
age (40). But the picture is more complex than
a simple lack of storage facilities: Although
storage after harvest when there is a glut of
food would seem to make economic sense, the
farmer often has to sell immediately to raise
cash.
In contrast, in the developed world, pre-retail
losses are much lower, but those arising at the
retail, food service, and home stages of the food
chain have grown dramatically in recent years,
for a variety of reasons (41). At present, food is
relatively cheap, at least for these consumers,
which reduces the incentives to avoid waste. Con-
sumers have become accustomed to purchasing
foods of the highest cosmetic standards; hence,
retailers discard many edible, yet only slightly
blemished products. Commercial pressures can
encourage waste: The food service industry fre-
quently uses “super-sized”portions as a compet-
itive lever, whereas “buy one get one free”offers
have the same function for retailers. Litigation
and lack of education on food safety have lead
to a reliance on “use by”dates, whose safety
margins often mean that food fit for consump-
tion is thrown away. In some developed
countries, unwanted food goes to a landfill
instead of being used as animal feed or compost
because of legislation to control prion diseases.
Different strategies are required to tackle the
two types of waste. In developing countries, pub-
lic investment in transport infrastructure would
reduce the opportunities for spoilage, whereas
better-functioning markets and the availability
of capital would increase the efficiency of the
food chain, for example, by allowing the intro-
duction of cold storage (though this has implica-
tions for greenhouse gas emissions) (38). Existing
technologies and best practices need to be spread
by education and extension services, and market
and finance mechanisms are required to protect
farmers from having to sell at peak supply, lead-
ing to gluts and wastage. There is also a need for
continuing research in postharvest storage tech-
nologies. Improved technology for small-scale
food storage in poorer contexts is a prime can-
didate for the introduction of state incentives for
private innovation, with the involvement of small-
scale traders, millers, and producers.
If food prices were to rise again, it is likely
thattherewouldbeadecreaseinthevolumeof
waste produced by consumers in developed coun-
tries. Waste may also be reduced by alerting con-
sumers to the scale of the issue, as well as to
domestic strategies for reducing food loss. Ad-
vocacy, education, and possibly legislation may
also reduce waste in the food service and retail
sectors. Legislation such as that on sell-by dates
and swill that has inadvertently increased food
waste should be reexamined within a more in-
clusive competing-risks framework. Reducing
developed-country food waste is particularly chal-
lenging, as it is so closely linked to individual
behavior and cultural attitudes toward food.
Changing Diets
The conversion efficiency of plant into animal
matter is ~10%; thus, there is a prima facie case
that more people could be supported from the
same amount of land if they were vegetarians.
About one-third of global cereal production is fed
to animals (42). But currently, one of the major
challenges to the food system is the rapidly in-
creasing demand for meat and dairy products that
has led, over the past 50 years, to a ~1.5-fold
increase in the global numbers of cattle, sheep,
and goats, with equivalent increases of ~2.5- and
~4.5-fold for pigs and chickens, respectively (2)
(Fig. 1). This is largely attributable to the increased
wealth of consumers everywhere and most re-
cently in countries such as China and India.
However, the argument that all meat con-
sumption is bad is overly simplistic. First, there
is substantial variation in the production effi-
ciency and environmental impact of the major
classes of meat consumed by people (Table 2).
Second, although a substantial fraction of live-
stock is fed on grain and other plant protein that
could feed humans, there remains a very sub-
stantial proportion that is grass-fed. Much of the
grassland that is used to feed these animals
could not be converted to arable land or could
only be converted with majorly adverse environ-
mental outcomes. In addition, pigs and poultry
are often fed on human food “waste.”Third,
through better rearing or improved breeds, it
may be possible to increase the efficiency with
which meat is produced. Finally, in developing
countries, meat represents the most concentrated
source of some vitamins and minerals, which is
important for individuals such as young children.
Livestock also are used for ploughing and trans-
port, provide a local supply of manure, can be a
vital source of income, and are of huge cultural
importance for many poorer communities.
Reducing the consumption of meat and in-
creasing the proportion that is derived from the
most efficient sources offer an opportunity to feed
more people and also present other advantages
(37). Well-balanced diets rich in grains and other
vegetable products are considered to be more
healthful than those containing a high proportion
of meat (especially red meat) and dairy products.
As developing countries consume more meat in
combination with high-sugar and -fat foods, they
may find themselves having to deal with obesity
before they have overcome undernutrition, lead-
ingtoanincreaseinspendingonhealththatcould
50% 100%0%
On-farm Transport and processing
Food Service Home and municipal
Retail
Developing
countries
USA
UK
Fig. 3. Makeup of total food waste in developed and develop-
ing countries. Retail, food service, and home and municipal
categories are lumped together for developing countries.
[Source: (16,37–39)]
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otherwise be used to alleviate poverty. Livestock
production is also a major source of methane, a
very powerful greenhouse gas, though this can
be partially offset by the use of animal manure
to replace synthetic nitrogen fertilizer (43). Of
the five strategies we discuss here, assessing the
value of decreasing the fraction of meat in our
diets is the most difficult and needs to be better
understood.
Expanding Aquaculture
Aquatic products (mainly fish, aquatic molluscs,
and crustaceans) have a critical role in the food
system, providing nearly 3 billion people with at
least 15% of their animal protein intake (44).
In many regions, aquaculture has been suffi-
ciently profitable to permit strong growth; repli-
cating this growth in areas such as Africa where
it has not occurred could bring major benefits.
Technical advances in hatchery systems, feeds
and feed-delivery systems, and disease manage-
ment could all increase output. Future gains may
also come from better stock selection, larger-
scale production technologies, aquaculture in
open seas and larger inland water bodies, and
the culture of a wider range of species. The long
production cycle of many species (typically 6 to
24 months) requires a financing system that is
capable of providing working capital as well as
offsetting risk. Wider production options (such as
temperature and salinity tolerance and disease
resistance) and cheaper feed substrates (for in-
stance, plant material with enhanced nutritional
features) might also be accessed with the use of
GM technologies.
Aquaculture may cause harm to the environ-
ment because of the release into water bodies
of organic effluents or disease treatment chem-
icals, indirectly through its dependence on in-
dustrial fisheries to supply feeds, and by acting
as a source of diseases or genetic contamination
for wild species. Efforts to reduce these negative
externalities and increase the efficiency of re-
source use [such as the fish in–to–fish out ratio
(45)] have been spurred by the rise of sustain-
ability certification programs, though these mainly
affect only higher-value sectors. Gains in sustain-
ability could come from concentrating on lower–
trophic level species and in integrating aquatic
and terrestrial food production, for example, by
using waste from the land as food and nutri-
ents. It will also be important to take a more
strategic approach to site location and capacity
within catchment or coastal zone management
units (46).
Conclusions
There is no simple solution to sustainably feed-
ing 9 billion people, especially as many become
increasingly better off and converge on rich-
country consumption patterns. A broad range of
options, including those we have discussed here,
needs to be pursued simultaneously. We are
hopeful about scientific and technological inno-
vation in the food system, but not as an excuse
to delay difficult decisions today.
Any optimism must be tempered by the
enormous challenges of making food produc-
tion sustainable while controlling greenhouse
gas emission and conserving dwindling water
supplies, as well as meeting the Millennium De-
velopment Goal of ending hunger. Moreover, we
must avoid the temptation to further sacrifice
Earth’s already hugely depleted biodiversity for
easy gains in food production, not only because
biodiversity provides many of the public goods
on which mankind relies but also because we do
not have the right to deprive future generations of
its economic and cultural benefits. Together, these
challenges amount to a perfect storm.
Navigating the storm will require a revolution
in the social and natural sciences concerned with
food production, as well as a breaking down of
barriers between fields. The goal is no longer
simply to maximize productivity, but to optimize
across a far more complex landscape of produc-
tion, environmental, and social justice outcomes.
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Feed required to produce 1 kg of meat kg of cereal per animal
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Cattle: grazing (Africa, India) 27–31 –
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Farming Futures. J.R.B. is also affiliated with Imperial
College London. D.L. is a Board Member of Plastid AS
(Norway) and owns shares in AstraZeneca Public Limited
Company and Syngenta AG. We are grateful to J. Krebs
and J. Ingrahm (Oxford), N. Nisbett and D. Flynn
(Foresight), and colleagues in Defra and DflD for their
helpful comments on earlier drafts of this manuscript.
If not for his sad death in July 2009, professor Mike Gale
(John Innes Institute, Norwich, UK) would also have been
an author of this paper.
10.1126/science.1185383
REVIEW
Breeding Technologies to Increase
Crop Production in a Changing World
Mark Tester*and Peter Langridge
To feed the several billion people living on this planet, the production of high-quality food must
increase with reduced inputs, but this accomplishment will be particularly challenging in the face of
global environmental change. Plant breeders need to focus on traits with the greatest potential to
increase yield. Hence, new technologies must be developed to accelerate breeding through improving
genotyping and phenotyping methods and by increasing the available genetic diversity in breeding
germplasm. The most gain will come from delivering these technologies in developing countries, but
the technologies will have to be economically accessible and readily disseminated. Crop improvement
through breeding brings immense value relative to investment and offers an effective approach to
improving food security.
Although more food is needed for the rapidly
growing human population, food quality
also needs to be improved, particularly for
increased nutrient content. In addition, agricul-
tural inputs must be reduced, especially those of
nitrogenous fertilizers, if we are to reduce en-
vironmental degradation caused by emissions
of CO
2
and nitrogenous compounds from agri-
cultural processes. Furthermore, there are now
concerns about our ability to increase or even
sustain crop yield and quality in the face of dy-
namic environmental and biotic threats that will
be particularly challenging in the face of rapid
global environmental change. The current di-
version of substantial quantities of food into the
production of biofuels puts further pressure on
world food supplies (1).
Breeding and agronomic improvements have,
on average, achieved a linear increase in food
production globally, at an average rate of 32 million
metric tons per year (2) (Fig. 1). However, to meet
the recent Declaration of the World Summit on
Food Security (3) target of 70% more food by
2050, an average annual increase in production of
44 million metric tons per year is required (Fig. 1),
representing a 38% increase over historical
increases in production, to be sustained for 40
years. This scale of sustained increase in global
food production is unprecedented and requires
substantial changes in methods for agronomic
processes and crop improvement. Achieving this
increase in food production in a stable environment
would be challenging, but is undoubtedly much
more so given the additional pressures created
by global environmental changes.
Global Environmental Change Alters
Breeding Targets
Certain aspects of global environmental change
are beneficial to agriculture. Rising CO
2
acts as a
fertilizer for C3 crops and is estimated to account
for approximately 0.3% of the observed 1% rise in
global wheat production (4), although this benefit
is likely to diminish, because rising temperatures
will increase photorespiration and nighttime res-
piration. A benefit of rising temperatures is the
alleviation of low-temperature inhibition of growth,
which is a widespread limitation at higher latitudes
and altitudes. Offsetting these benefits, however,
are obvious deleterious changes, such as an in-
creased frequency of damaging high-temperature
events, new pest and disease pressures, and al-
tered patterns of drought. Negative effects of other
pollutants, notably ozone, will also reduce benefits
to plant growth from rising CO
2
and temperature.
Particularly challenging for society will be
changes in weather patterns that will require
alterations in farming practices and infrastructure;
for example, water storage and transport networks.
Because one-third of the world’sfoodisproduced
on irrigated land (5,6), the likely impacts on
global food production are many. Along with
agronomic- and management-based approaches to
improving food production, improvements in a
crop’s ability to maintain yields with lower water
supply and quality will be critical. Put simply, we
need to increase the tolerance of crops to drought
and salinity.
In the context of global environmental change,
the efficiency of nitrogen use has also emerged as
a key target. Human activity has already more
than doubled the amount of atmospheric N
2
fixed
Australian Centre for Plant Functional Genomics, University of
Adelaide, South Australia SA 5064, Australia.
*To whom correspondence should be addressed. E-mail:
mark.tester@acpfg.com.au
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