How many people can the earth support? Alex Evans

November 9, 2010 | More on Climate and resource scarcity, Economics and development | 7 comments

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.

7 comments »

Debanjana on November 15th, 2010 at 2:03 pm:

one thing was missed out about India while doing the cross country analysis…Indian are mostly vegetarian and most of the poorer population can not afford to buy milk..so it remains interesting to see how India deals with malnutrition among the low income vegetarian population, which seems to be quite a unique problem.
@steadystater on November 15th, 2010 at 8:09 pm:

Being vegetarian is not a diet that leads to malnutrition. Being too poor to buy food leads to malnutrition. A vegetarian (and vegan) diet easily provides all the nutrition required by a human being, with using less resources. On top of that, if it is balanced, it is healthier than a diet that includes meat and dairy. Vegetarians are less likely to have heart disease, suffer from strokes or contract diabetes, as well as a decreased risk of cancer and gastrointestinal problems. Studies have proven this to be true and even the ADA recognizes vegetarianism as a nutritionally sound diet.
@steadystater on November 15th, 2010 at 8:10 pm:

Oops, something went wrong with that, cut out some of my comment, here's the whole thing:

Being vegetarian is not a diet that leads to malnutrition. Being too poor to buy food leads to malnutrition. A vegetarian (and vegan) diet easily provides all the nutrition required by a human being, with using less resources. On top of that, if it is balanced, it is healthier than a diet that includes meat and dairy. Vegetarians are less likely to have heart disease, suffer from strokes or contract diabetes, as well as a decreased risk of cancer and gastrointestinal problems. Studies have proven this to be true and even the ADA recognizes vegetarianism as a nutritionally sound diet.

Vegetarians also usually experience an increase in energy and mental clarity after ridding their body of meat and dairy, but that's just something you'll have to take my word for – don't know if there are studies on that.

Plus, it is cheaper and more efficient to feed vegetarians. Instead of requiring the vast swaths of land and resources to produce the protein in an animal, a much smaller amount of farmland and resources can be used to grow more protein.

So, to say that their are vegetarian and imply that is why many suffer from malnutrition is erroneous. You can simply support more people on a vegetarian diet, and they can still eat well and be very healthy – if not more so.

Cheers,
Joshua
Mike on January 24th, 2011 at 3:44 pm:

People who say vegetarians suffer from malnutrition have completely failed to grasp any sense of reality. Dairy food is one of the worst foods that you can possibly eat. We are the only species that drinks milk after infancy. Think about it – what does a Goriila eat?

Thinking that you need milk & dairy for calcium -completely false!
Thinking you need meat for protein – completely false!

There are numerous studies a that are trying to educate you on what you instinctually know, that a plant-based diet has more benefits than an animal based diet. You can take control of your health by eating a plant based diet rather than relying on Doctors or other health experts.
Giant industries are lieing to you!
There is no money in telling you to eat that apple off your apple tree, but the meat and dairy industry are only benefiting from you succumbing to their lies. Think about this and begin to question what you see on television and in magazines. Ask yourself, if I was starving and in front of me were apples or a dead cow, which one would you instinctually gravitate towards?

And for anybody who thinks that I am weak or suffer from malnutrition through being a vegan, I'll challenge you to a fitness competition.

Best of luck.
Rick on May 13th, 2011 at 11:27 am:

Interesting question and comments, but this question is too general. Obviously it ended up all about vegetarians. And that, of course, is hardly the point of the question.
Is China and more importantly, India, and Africa doing anything about child-birth rates. Becuase that is the ugly truth at the end of the day. The world needs to equalize its birth-rates with its death-rates(due to longer living old-age).
Secondly, when you say support, do you mean is there enough jobs for people to even be able to buy food, clothing, shelter, … the "bare" necesseties. ? Shockingly, NO !,
The answer is "jobs" in general will not provide enough money for most. There may be a lot more jobs in the future, but you can hardly call "outsourcing" a miraculous job creation. In fact, the few extremely rich will become even richer, while the ever-expanding poorer masses become even poorer. …(contined on next comment).
Rick on May 13th, 2011 at 11:28 am:

(…cont. from last comment).
Future Technologies will most "obviously" force all remaining jobs, work,…, to become even more and more "irrelevant", therefore more people is not good, since the income to buy food will not be there.
And we now know, we cannot depend on Gov't, or synonymously, Corporations',.., to be there. Seriously, "…the caring and compassion of world gov'ts, and corporations" -I don't know anyone who could seriously mean that. ?! And yes, my glass is half-empty
As cruel as it may appear to some, but in this case, less is truly more.
Consider techology one last time, and this fact: "we need the earth, but earth does NOT need Humans"
So, in case of technological disasters, which will happen, we need to roughly know how much of the "natural" earth can be used to comfortably sustain/support humans, livestock, … "without" technology, and therein will lie you real answer to how many "people can the earth support". ?
In the above scenario, we have sadly far surpassed that level already.
rabe12 on October 31st, 2011 at 2:15 pm:

I don't think that was necessarily what the author was saying. I think he was stating that there are poor people who also happen to be vegetarians who cannot afford to buy any more protein rich foods. He was saying that rice alone made up 60% of their diet, which is a little more than recommended for daily consumption based on percentages.

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