How many people can the earth support?

Here’s Lester Brown’s take:

One of the questions I am often asked is, “How many people can the earth support?” I answer with another question: “At what level of food consumption?” Using round numbers, at the U.S. level of 800 kilograms of grain per person annually for food and feed, the 2-billion-ton annual world harvest of grain would support 2.5 billion people. At the Italian level of consumption of close to 400 kilograms, the current harvest would support 5 billion people. At the 200 kilograms of grain consumed by the average Indian, it would support 10 billion.

Of the roughly 800 kilograms of grain consumed per person each year in the United States, about 100 kilograms is eaten directly as bread, pasta, and breakfast cereals, while the bulk of the grain is consumed indirectly in the form of livestock and poultry products. By contrast, in India, where people consume just under 200 kilograms of grain per year, or roughly a pound per day, nearly all grain is eaten directly to satisfy basic food energy needs. Little is available for conversion into livestock products.

Among the United States, Italy, and India, life expectancy is highest in Italy even though U.S. medical expenditures per person are much higher. People who live very low or very high on the food chain do not live as long as those at an intermediate level. People consuming a Mediterranean-type diet that includes meat, cheese, and seafood, but all in moderation, are healthier and live longer. People living high on the food chain can improve their health by moving down the food chain. For those who live in low-income countries like India, where a starchy staple such as rice can supply 60 percent or more of total caloric intake, eating more protein-rich foods can improve health and raise life expectancy.

I can’t vouch for the accuracy of Brown’s figures – but he’s totally right that the whole question of diet is fundamental to whether we manage to feed the world’s rising population. I’m always struck by how the global food policy conversation often accepts demand projections – such as the World Bank’s estimate that we’ll need to produce 50% more food by 2030 – more or less uncritically.

In fact, as Brown’s final paragraph above implies, meeting these business-as-usual projections also implies that we cheerfully accept continuation of current increases in overweight, obesity, diabetes, heart disease and so on – not just in OECD economies, but increasingly in the developing world too.

Unfortunately, as I noted back in September, no OECD governments are yet making any real headway in nudging their citizens towards diets that are healthier, more environmentally sustainable and more compatible with development and social justice. They need to find a way.