| “How
Much Food Will We Need in the 21st Century?” Environment Watch 1997,
by William H. Bender
Ever since Malthus
[predicted that population growth would outstrip food production], society
has worried periodically about whether it will be able to produce enough
food to feed people in the future. Yet until recently most of the debate
surrounding the issue of food scarcity focused on the potential for
increasing the food supply. The key questions was whether there would
be enough land and water to produce the amount of food needed and whether
technology could keep increasing the yields of food grains. Now, however,
scientists are growing concerned that the intensive use land, energy,
fertilizer, and pesticides that modern agriculture seems to require
jeopardizes the health of the environment. This anxiety has been integrated
into the general debate about food scarcity, but interestingly enough,
the question of the demand for food—including the specific physiological
needs and dietary desires of different peoples—has not. In fact,
relatively little attention has been paid to the issue of demand despite
the fact that like energy and water, food can be conserved and the demand
for it adjusted to meet human needs and lessen the burden that modern
agriculture places on the environment.
Unlike with many other forms of consumption, there are limits to the
physical quantity of food that people can consume. In a number of high-income
countries, that limit seems to have been reached already. If global
population does double by 2050, as many have predicted, providing everyone
with a rich and varied diet (equivalent to that enjoyed by today’s
wealthiest countries) would only require a tripling of food production.
Alternatively, with sufficient improvements in efficiency and adoption
of a healthier diet in high-income countries, it would be possible to
provide such a diet for the entire global population with just a doubling
of food production. But even a doubling of current production could
strain Earth’s ecosystems, as critics of modern agriculture’s
intensive use of resources will attest. Clearly, then, increases in
food demand will have to be slowed if we hope to achieve a sustainable
agricultural system. Central to the issue of demand, however, is the
question of how much food the world really needs.
From an analytical standpoint, the amount of food a given population
(be it a country, a region, or the world) actually needs is the product
of two factors: the number of people and the average (minimal) food
requirement per person. The amount of food the population consumes,
however, is determined not only by its basic needs but also by its income
and dietary preferences. This difference is particularly important in
high-income countries, where crops that could be consumed directly are
instead fed to animals to produce eggs, meat, and milk. Finally, the
amount of food a given population requires (i.e., has to produce or
import) depends on how much is wasted in going from farm to mouth as
well as on its level of consumption. In mathematical terms,
Req = Pop. x PFR
x Diet x Eff
where Req is the
total number of food calories that has to be produced, Pop is population,
PFR is the number of calories per person that is needed to sustain life
and health. Diet is a factor reflecting the conversion of some plant
calories to animal calories, and Eff is the ratio of calories available
in the retail market to those consumed.
This article will address the neglected issue of food demand in terms
of the four variables of this equation. In the process, it will question
some of the assumptions previous analysts have made, particularly with
regard to desirable diets and food system efficiency. Though not definitive,
the analysis strongly suggests that the right policy choices can reduce
the growth in the global demand for food. Indeed, the potential scope
of such a reduction appears to be substantial: As Table 1 on the next
page shows, vastly different numbers of people can be supported by a
given amount of agricultural production depending on dietary habits
and degrees of efficiency.
Population
Global population will play an important role in determining how much
food we will require in the future. For this reason, attempts to calculate
future food requirements depend upon projections of population growth.
Although demographers generally agree that the current global population
will double by the middle of the next [21st] century, considerable uncertainty
accompanies these projections. The United Nations estimates of the world’s
population in 2050, for example vary from 7.9 billion to 11.9 billion.
If global population reaches the higher value rather than the lower
one, global food requirements will be 50% higher.
National and international policies that provide family planning services,
maternal education, and social support systems can affect population
growth, and these policies will undoubtedly have the single largest
effect on food requirements in the 21st century. The availability of
food will also play a role. However, famine—the most dramatic
example of lack of food—has fortunately been largely eliminated
(except during wars) and no longer ranks as a major factor in global
population growth. Even so, the relative abundance of food has a direct
effect on the other key factors that influence population growth, and
combined with the subtle influences exerted by the food and agriculture
sector. It can have a significant impact. For example, in rural agricultural
societies, the demand for agricultural labor affects fertility rates,
while reductions in child mortality (which are influenced by food availability)
usually precede reduction in fertility rates.
Physiological Requirements
Physiological food requirements, represented by PFR in the equation,
are determined by several factors, including the population’s
age and gender distribution, its average height and weight, and it activity
level. One may compute such requirements in two different ways, using
either actual circumstances or normative ones (such as desired heights
and weights or activity levels).
Around the world, actual per capita caloric consumption varies from
a low of 1,758 calories per day in Bangladesh to a high of 2,348 calories
per day in the Netherlands. Caloric consumption is higher in the Netherlands
for several reasons. First, the population is generally older, and adults
require more food than children. Second, people in the Netherlands are
on average taller and heavier than those in Bangladesh and, therefore,
need more food. (Lower activity levels in the Netherlands partially
offset these factors, however.) If the actual consumption levels in
these two countries were to change, either the weights of individuals
or their activity levels would have to change accordingly. Caloric consumption
levels vary by no more than one-third on a national basis—far
less than the variation in caloric availability.
When making future projections, normative considerations can also be
very important. A population’s general health, for instance, affects
the amount of food it needs. Parasites and disease can substantially
increase an individual’s energy requirements, with fever, for
example, raising his or her basal metabolic rate (the number of calories
he or she uses when at rest) approximately 10% for every one degree
Centigrade increase in body temperature. Disease can also impair the
body’s ability to absorb nutrients, while parasites siphon away
food energy for their own use. Although not important globally, health
factors are highly significant in certain low-income countries. In fact,
in localized situations health interventions may be more effective than
merely increasing the food supply in helping people to satisfy basic
physiological requirements.
Of course, to qualify as truly sustainable, the world’s agricultural
system has to produce enough calories to ensure food security around
the globe. This is a normative concept, as is clear in the commonly
accepted definition of food security: “access by all people at
all times to enough food for an active, healthy life.” Thus, for
future projections, we could consider a world with lower levels of undernutrition
and stunting, leading to higher food requirements.
Table 2 shows estimates of physiological food requirements for the world
as a whole, for high-income countries, and for low-income countries,
all based on current circumstances. High-income countries use much more
than twice as much food per person. This variation is not due to differences
in calories actually consumed but to differences in diet and the lower
efficiency of food systems in those countries.
Dietary Patterns
Diets are largely determined by economic factors, particularly prices
and incomes. In Africa, for example, people derive two-thirds of their
calories from less expensive starchy staples (including cereals, roots,
and tubers) and only 6% from animal products. In Europe, on the other
hand, people derive 33% of their calories from animal products and less
than one-third from starchy staples. The global diet falls somewhere
in the mid-range between these two extremes.
As people’s level of income increase, the share of starchy staples
in their diet declines, and the shares of animal products, oils, sweeteners,
fruits, and vegetables increase….
The overall increase in food availability over the last several decades,
while a welcome development, has created problems of its own. As people
consume more animal products, they tend to consume more animal fats
than recent medical research has shown to be healthy. Currently, the
World Health Organization (WHO) recommends that people limit their dietary
intake of fat to no more than 25 to 20 percent of the daily intakes.
At present, 16.8% of the global population lives in high-income countries,
where, on average, fat consumption exceeds the 30% level. But health
concerns have clearly begun to affect consumption patterns in those
countries: Despite rising incomes and relatively stable prices, beef
consumption has declined in a number of countries since the mid-1970s.
In the U.S., for instance, per capita beef consumption has dropped 25%.
(Overall meat consumption in the U.S. has remained approximately constant,
however, because people merely shifted to eating poultry.)
Clearly, public policy that encourages people to reduce their consumption
of animal fat has two benefits. It improves the health of the population
while reducing the pressure that increased food production places on
the global agricultural system. Table 3 shows the conversion rates of
grain to animal products in terms of two common measures: kilograms
and calories. For the past 30 years, approximately 40% of all cereal
grains produced globally have been used for feed, with 50% being used
for food. (The remaining 10% have gone to seed, been used in processing,
or ended up as waste.) As Table 2 shows, however, the use of grain for
feed is much higher in high-income countries.
Efficiency
The last factor affecting global food requirements is the efficiency
with which food moves from farms to human mouths. Efficiency actually
has two components, one pertaining to marketing and distribution and
one pertaining to “end use.” Losses in marketing distribution
such as those due to rodents and mold, are important in low-income countries
but decline steadily with increases in income. Inefficiencies in end
use, which include losses due to spoilage, processing and preparation
waste, and plate waste, are most significant in high-income countries,
however.
The United Nations
Food and Agriculture Organization (FAC) estimates that per capital caloric
availability (i.e., the amount of food that appears in the retail market)
ranges from a low of 1,667 calories in Ethiopia to a high of 3,902 calories
in Belgium-Luxembourg. These two figures differ by 234%--much more than
the 33% difference in physiological consumption. Because it is physiologically
impossible for the population of an entire country to consume an average
of 3.902 calories, we know that a substantial amount of food in high-income
countries is never consumed. According to estimates, losses from end-use
inefficiencies equal to 30 to 70 percent of the amount of food actually
consumed. With the exception of Belgium-Luxembourg, it is middle-income
countries such as Greece, Ireland, Yugoslavia, Hungary, Bulgaria, Egypt,
and Libya that have the highest levels of waste. But in every country,
where per capita income is more than $1,500 (U.S.), at least 20% more
food is used than is consumed. The computed values for the end-use efficiency
factor in Table 2 also reflect the discrepancy between high- and low-income
countries.
It is unclear to what extent these losses are a necessary component
of increases standards of living because little analysis has been done
on the sources of this waste. Some intercountry comparisons provide
useful insights, however. The Netherlands, Finland, Japan, and Sweden,
which have comparable levels of income, waste only about 35% (on a per
capita caloric basis). While the U.S., Belgium-Luxembourg, Switzerland,
and Italy waste nearly 60%. This suggests that there is scope for reducing
food requirements without lowering standards of living, much as high-income
countries have done with energy use since the 1970s.
Given the current distribution of food consumption and food system efficiency,
if every middle- and high-income country were to reduce its level of
waste to 30%, global food requirements would decline 7.4%. (If consumption
of animal products were to decrease in proportion, requirements would
decline 12.5% owing to the lower demand for feed.) Clearly, as global
incomes increase and the number of people living in countries with low
food system efficiency continues to grow, the level of end-use waste
will become an increasingly important part of overall food requirements.
Final Thoughts
By its very nature, agricultural production has significant impacts
upon natural ecosystems and the environment. There is little question
that agricultural production must increase to meet population growth,
but the magnitude of the increase necessary to improve human welfare
is very much a question of policy tradeoffs between demand management
and supply promotion.
Food is the only sector of the economy that has reached satiation for
a large portion of the world’s population. Tripling world food
production would provide sufficient food for a doubled global population
to have a varied, nutritious, and healthy diet comparable to today’s
European diet. The same goal could be reached by slightly more than
doubling agricultural production if an effort were made to improve food
system efficiencies and if diets low in fat became commonplace. This
change will only take place if public policy creates explicit incentives
for healthier diets and more efficient food systems, however.
It is environmentally and medically prudent to prevent the levels of
waste and fat consumption in the wealthier developing economies from
rising to those seen in North America today. It is also fiscally prudent:
Grain imports tend to rise rapidly in maturing developing economies,
so that decreased food system efficiency and increased fat consumption
can lead directly to the loss of vital foreign exchange. Therefore,
self-interest can be used to dramatically improve the long-term sustainability
of the global agricultural system.
(Tables are available
in the Resource Book in the classroom.)
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