Four billion more people than the 7.2 billion now alive could be fed an adequate diet if current crop production devoted to nonfood uses, such as animal feed and biofuels, were switched to direct consumption. This is one the fascinating calculations made in a new article published in Science by a team of researchers led by Paul West, a researcher at the University of Minnesota's Institute on the Environment. West and his colleagues are looking for "leverage points" in global agriculture that would reduce humanity's impact on the natural world while at the same time providing more than enough food for the 9 billion or so people who will be alive in 2050.
This analysis stands in stark counterpoint to the perennial apocalyptic prophecies of impending famine spawned by overpopulation. Last year, in the Proceedings of the Royal Society B, the Population Bomber himself, Paul Ehrlich and his wife Anne asked yet again, "Can a collapse of global civilization be avoided?" and answered that the "human predicament is driven by overpopulation" among other horrors. In his 2013 screed, Ten Billion, Cambridge University computer scientist Stephen Emmott argued that humanity's growing population constitutes "an unprecedented planetary emergency." In addition, Emmott claimed, "By 2050, 1 billion hectares of land is likely to be cleared to meet rising food demands from a growing population. This is an area greater than the U.S."
West and his colleagues focus their analysis on 17 major crops consisting of the 16 highest-caloric crops consumed as food and cotton. They occupy 58 percent of the world's croplands and produce 86 percent of world's crop calories. They are specifically looking to see if it will be possible to boost crop production on the current land base while at the same time cutting inputs like fertilizer and irrigation that sometimes generate deleterious side-effects on the natural world.
One particularly promising strategy is closing the "yield gap." The yield gap is the difference between current yields and those possible using modern farming techniques. For example, corn yield in the United States averages 162 bushels per acre. In Africa, India, and Latin America, corn yields average 32, 41, and 48 bushels per acre respectively. The world average is 81 bushels per acre. West and his colleagues calculate that raising yields in low performing areas to 50 percent of the attainable level would produce enough calories to meet the basic need of about 850 million people. This may be too conservative a figure.
In 2012, Jesse Ausubel, director the Human Environment Program at Rockefeller University, and his colleagues suggested that the world was on the brink of "peak farmland." Future agricultural productivity will be so great that farmers will increasingly spare more land for nature. How much? Depending on how demand for biofuels develop farmers will return between 146 million and 400 million hectares to nature. The first is an area the size of France, Spain, Portugal, and Britain combined, and the second is about equal to all the land in the United States east of the Mississippi River. This is quite in contrast to Emmot's baleful auguries about future land use.
Current practices of using modern fertilizers also result in harmful side effects including enhanced man-made global warming and the creation of algal blooms and dead zones in the oceans. Nitrogen and phosphorous fertilizers have been critical to boosting crop production over the past century. University of Manitoba environmental researcher Vaclav Smil reckons that 40 percent of the world's dietary protein now originates from synthetic nitrogen fertilizers. West and his colleagues calculate that the nutrients in harvested crops account for only 40 percent of the nitrogen fertilizer and 52 percent of the phosphorous spread by farmers, much of the rest runs off the fields into streams, lakes and the oceans. Given this excess, they estimate nitrogen and phosphorous applied to wheat, rice and corn could be cut by 14 to 29 percent and 13 to 33 percent respectively while maintaining current yields.
Irrigation accounts for about 70 percent of all freshwater withdrawals and 90 percent of water consumption. The researchers looked only at croplands where evaporation rates exceed precipitation rates. Just raising the productivity of irrigated land currently languishing in the bottom 20th percentile to above that benchmark would decrease water consumption by 8 to 15 percent while keeping food production constant.
The "diet gap" is defined as those crop calories that people could eat that do not end up in the food supply. Most of these are crops grown for animal feed and biofuels. Between 1961 and 2009, the portion of crops consumed directly as food has dropped from 57 to 51 percent. As noted in the beginning, if people consumed food crops directly, 70 percent more calories would become available, which is enough to feed an additional 4 billion people. The researchers figure that corn production in the United States accounts for 19 percent of their diet gap, representing enough calories to feed 760 million people. With considerable understatement, the researchers observe, "Although the diet gap presents opportunities to improve food security, cultural preferences and political obstacles create large challenges to reducing meat as well as overconsumption." Translation: People love to eat meat.
The United Nations Food and Agriculture Organization (FAO) reports that average global meat consumption per capita increased from 53 pounds in 1965 to 91 pounds today. The average American eats about 270 pounds of meat annually. Interestingly, the per capita consumption of beef on a global basis has been essentially flat while there are big gains in pork and chicken. Recent research suggests that switching from a high meat diet to a vegan diet would cut an individual's greenhouse emissions associated with food production in half.
A lot of food is wasted. West and his colleagues cite a report from the FAO that estimates that, for example, around 30 percent of cereal grains are lost between harvest and consumption. They calculate that curbing consumer waste of foods made from wheat, rice, vegetables, and meat in the United States, China, and India could feed 413 million people.
What makes this study noteworthy is that it assumes no new agricultural or food production technologies, instead its analysis concludes that more judiciously deploying what is already available would be more than enough feed the world's future population. Nevertheless, significant new food and agricultural technologies are in the pipeline. Consider the problem of excess nitrogen. Biotechnology researchers are hard at work at developing crops that use much less nitrogen fertilizer as they increase yields. For example, the biotech seed company Arcadia Biosciences announced in 2013 that nitrogen use efficient variety of rice out-produced conventional varieties while using 50 percent less nitrogen. Meanwhile researchers at the International Rice Research Institute are heading up a project to endow rice with the more efficient C4 form of photosynthesis found in corn. If successful, the new rice varieties would need less water and fertilizer and yield 50 percent more grain than the best current varieties.
Solutions to providing more food may also come from outside of traditional agriculture. The concept of a diet gap makes it clear that growing a pound of meat takes a lot of feed and water. A 2011 study in Environmental Science & Technology calculated that vat-grown meat could lower energy use by approximately 7–45 percent, shrink greenhouse gas emissions by 78-96 percent, cut land use by 99 percent and reduce water use by 82-96 percent. And in 2013 other researchers reported that they have figured out how to turn abundant cellulose locked up in trees and grass into edible starches and glucose suitable for fermenting into biofuels.
West and his colleagues acknowledge that more work is needed to figure out how to get best practices that they identified widely adopted. Nevertheless they conclude that "a relatively small set of places and actions could provide enough new calories to meet the basic needs for more than 3 billion [and simultaneously] address many environmental impacts with global consequences."
In other words, the prophets of overpopulation doom and imminent global famine will likely once again be disappointed.