I have been thinking about future food supplies. Not long ago I re-read portions of E. O. Wilson's 2002 book The Future of Life. He wrote,
"If everyone agreed to become vegetarian, leaving little or nothing for livestock, the present 1.4 billion hectares would support about 10 billion people."A number of authorities report that world "arable land" totaled 1.38 billion hectares in 2008. This article, which I consider most reliable, reports 1.365 billion as of 2005. This is less than the land under cultivation, however, because "arable" counts only land that doesn't need irrigation. All cultivated land totaled 1.73 billion hectares in 2005. Still, all the figures are in a range that is unlikely to change much unless huge breakthroughs are made in land usage effectiveness.
Just over 30% of the cultivated land is used for livestock, about 0.52 billion hectares. This includes land that grows crops which are fed to livestock. It leaves 1.2 billion hectares to produce all the vegetable foods for the world population of seven billion persons. That resource produces:
- 57 million metric tons (MTm) of beef
- 104 MTm of pork, ham and other swine meats
- 87 MTm of chicken meat
- 13 MTm of other fowl
- 700 MTm of milk (all kinds)
- 64 MTm of eggs
As world prosperity rises, larger numbers will want better diets. Suppose meat consumption in the West could be reduced by 20%, and four billion people in Asia and Africa were to demand an increase of meat availability to that level (90 kg per person per year), could we produce it?
Five billion times 90 kg = 450 MTm per year. 450/261 = 1.72, a 72% increase. If we assume an equivalent increase in the demand for milk and eggs (less likely for reasons we will get to soon), it would require either a 72% increase in land devoted to livestock production—from 0.52 billion Ha to 0.89 billion Ha—or an equivalent increase in livestock productivity per hectare. Neither is likely.
By 2025, just 13 years from now, there are expected to be eight billion of us. Just to feed that extra billion, assuming the current distribution of diet, will require either a 14% increase in average productivity, or a 14% increase in cultivated acreage. This is also unlikely.
Several factors complicate such an analysis. Firstly, few adult Asians can drink cow or buffalo milk because of lactose intolerance. Their "milk" of choice is soy milk. The leftover soy roughage is fed to livestock, though it needs to be mixed in with more palatable fare, or the animals won't eat it. Secondly, increasing amounts of "cultivated" land are being turned over to ethanol production for motor fuel. This will simply have to come to an end within the next couple of decades, or riots will ensue. Thirdly (and finally for this discussion), it takes 2-3 kg of vegetable feed to produce one kg of chicken meat, but 10-12 kg to produce a kg of beef. Pork is in the middle at 3.5-4. I foresee a continuing trend away from cattle to other animals. Beef will become a rare "premium" treat.
I didn't mention seafood anywhere above. While a there is a little on-land aquaculture, most fish- and prawn-farming is done at sea, so it doesn't impact the amount of arable or cultivable land, and is presently a small portion of total seafood consumption; most seafood is wild caught. But this is as good a time as any to state that fish catches have been decreasing for years, and are likely to drop by half in the next 10-20 years. That will increase the pressure on meats and on sea- and land-based aquaculture.
This brings me back to the Wilson quote. Sometime between 2050 and 2100 AD, world population could rise to nine billion, then ten billion. There is a lot of hope, with little justification, that population will level off between nine and 9.5 billion prior to 2100. Suppose it does: there will still be no way to afford using so much land for livestock.
There will always be marginal grasslands where grazing animals are the best way to turn sunlight into calories, and there will be byproducts like extracted soy meal that people won't eat. The conclusion I must draw from my rough calculations is that everyone except a few of the wealthiest individuals will be eating much less animal food than at present. Fashionable item in future trousseaux: a vegetarian cookbook.