The world population will hit 10 billion by 2100. That's what the United Nations says in its latest estimate.
Is this finally the "population bomb" that will end the world as we know it, as Paul Ehrlich wrongly predicted in 1968? Or can we really feed this many people—even with sustainable agriculture?
Well, there are promising signs that we will be able to feed a growing world. Earlier this year, two French research organizations released Agrimonde, a report detailing two possible scenarios for feeding 9 billion over the next five decades. One model emphasized economic growth over the environment and required an estimated 80 percent growth in farm productivity. The other emphasized an agro-ecological system, requiring a 30 percent growth in agricultural productivity. What both models had in common: They used a global average of 3,000 calories per person per day.
Three thousand calories is well below our current consumption in the United States (and other blue regions in the map below). In other words, we can feed the world if you stop eating so many steaks, snacks, and sodas.
What complicates these projections is the methods we use for measuring global food production—maximum yields, arable land, and per capita energy intake. All these variables are complex and highly subjective, so the deep structure of debate about feeding the world comes down to data.
Historian Warren Belasco argues in A History of the Future of Food that hunger is newsworthy only when it's countable, so the recurring debates—biotechnology versus agroecology—have really been battles over which data the sages and oracles use to predict the future of food. Ending hunger is more than just redistributing calories, Belasco says. It's about questioning the underlying assumption involved with concentrating calories into profitable and wasteful products.
In short, calculations of the total food supply require a comprehensive audit of the global food chain. Production of calories is only the start.
Furthermore, the 3,000-calories-a-day solution comes with cultural assumptions. Think about a school lunch. Chances are it's made with wheat and corn. And we generally give kids liquid milk instead of cultured yogurts. Those choices aren't universal.
Until we answer the more qualitative questions—how many people do we feed for how long, with what technology, and with what kind of stability—any population estimates will continue fostering competing visions by the world's cornucopianists or Malthusian catastrophists.