Consider the recent predictions for population growth derived by the United Nations (UN): World Population Prospects: The 2012 Revision. The current world population is about 7 billion. The best guess of the future population places it at 10.85 billion in 2100, within the lifetime of a person born today. That is a significant 55% increase yet to come. However this is only an estimate. The UN dataset contains a range of possibilities from 6.75 billion to 16.64 billion (-4% to +238%). Consider what the population would be if the world went on its merry way procreating at the same rate as now; the UN’s constant fertility estimate would yield a population of 28.64 billion (+409%) in the year 2100. Human behavior must change considerably if we are to avoid a Malthusian future.
One way or another, the world is going to experience a great increase in the demand for food. It will probably be due to a large increase in the world’s population as well as a change in the type of food product desired.
It is not widely recognized that total population does not necessarily provide the greatest leverage on food production. Of perhaps greater importance is the type of diet that people aspire to. Humans have always had a desire for more meat than has been available. As the population has become wealthier, on average, meat consumption has increased. Much of agricultural production is aimed not at feeding people directly, but at feeding the animals that produce the meat we so much enjoy.
Lester R. Brown refers to this willingness to spend more of one’s income on animal products as "moving up the food chain." Brown discusses the issues related to food production in his book Full Planet, Empty Plates: The New Geopolitics of Food Scarcity.
If we want meat we must feed an animal to create the meat. If we want affordable meat we must mass produce it in an industrial setting: factory farms where animals of a given species are herded together and fed a mixture of feed (mostly grain, no matter what their natural diet might be) and chemicals needed to aid digestion, stimulate weight gain, and to avoid diseases. The cost of meat then is closely proportional to the amount of food the associated animal consumes.
And cost does matter.
Brown puts the agricultural demands of a meat-heavy diet in perspective.
"The average American, in contrast, consumes roughly 1,400 pounds of grain per year, four fifths of it indirectly in the form of meat, milk, and eggs. Thus the total grain consumption per person in the United States is nearly four times that in India."
As the population of India increases its wealth, the demand for meat, milk, and eggs is going to increase—a trend that Brown tells us has already been observed.
A more graphic perspective on what moving up the food chain would mean if all humanity attempts to do it is provided by Chandran Nair, who is concerned that world resources cannot maintain such a level of food production.
Brown has published an article at the Earth Policy Institute website that illustrates this effect in action as China attempts to keep up with the demand for its favorite meat—pork: Can the World Feed China? China has labored mightily to be self-sufficient in grain production, but it just cannot keep up with demand.
"In 2013, the world consumed an estimated 107 million tons of pork—half of which was eaten in China. China’s 1.4 billion people now consume six times as much pork as the United States does. Even with its recent surge in pork, however, China’s overall meat intake per person still totals only 120 pounds per year, scarcely half the 235 pounds in the United States. But, the Chinese, like so many others around the globe, aspire to an American lifestyle. To consume meat like Americans do, China would need to roughly double its annual meat supply from 80 million tons to 160 million tons. Using the rule of thumb of three to four pounds of grain to produce one pound of pork, an additional 80 million tons of pork would require at least 240 million tons of feedgrain."
China, similarly to most agricultural producers, is already growing about as much grain as possible.
China is not the only country attempting to move up the food chain.
Brown’s book is devoted to detailing the reasons why food production is having a difficult time keeping up with demand. Among the reasons discussed are lack of water for irrigation, little new land to cultivate, rising temperatures, and diminishing returns in terms of productivity gains.
He is greatly concerned about the tendency to use water in an unsustainable manner because the ability to produce food is tied to the water supply. If water usage is unsustainable, in terms of drawing down water supplies faster than they can be replenished, then food production is unsustainable. He refers to such a condition as living in a "food bubble."
Dramatic gains in grain production have come from increased productivity of existing cultivated land. Those improvements seem to have played out leaving many countries with stagnant farm yields.
"Impressive though the growth is over the last 60 years, the pace has slowed during the last two decades. Between 1950 and 1990, the world grain yield increased by an average of 2.2 percent a year. From 1990 to 2011, the annual rise slowed to 1.1 percent. In some agriculturally advanced countries, the dramatic climb in yields has come to an end as yields have plateaued."
Farmers are already using more fertilizer than the land can accommodate in order to get the last bit of yield. As a result, the excess is running off and entering our water systems. This pollution becomes not only a human health hazard, but a powerful disrupter of aquatic ecosystems that we also depend upon for food supply.
Global warming is also an issue going forward. Plants have evolved to thrive in a narrow range of temperature and other climatic conditions. Rising temperatures and changing weather patterns can have a significant effect on crop productivity.
"….as temperature rises, photosynthetic activity in plants increases until the temperature reaches 68 degrees Fahrenheit. The rate of photosynthesis then plateaus until the temperature reaches 95 degrees Fahrenheit. Beyond this point it declines, until at 104 degrees Fahrenheit, photosynthesis ceases entirely."
Concerns about rising temperatures have sent investigators off to look at historical data correlating crop production with correlated temperature history. Brown describes two studies, one of which concluded:
A second study of corn and soybeans yields concluded that a similar rise in temperature would diminish yields by 17 percent for each crop.
Brown also discusses the issues of soil erosion, desertification, and the conversion of cultivatable land to non-food crops, but the picture should be sufficiently clear by now: large increases in grain production will be difficult to attain. Not everyone will be able to enjoy the diet they might prefer.
Brown predicts that food prices will rise and become more volatile as demand increases. He expects this to lead to more political unrest, particularly in countries where food cost is a major budgetary component. He expresses his concerns in his conclusion to the article about China and grain demand.