Oil And Population: A New Estimate
By Peter Goodchild
03 October, 2012
One might argue that about 2 billion people will die of famine by the year 2030 as a result of the depletion of petroleum, with about an equal number of lost or averted births. The reasoning is that the energy for modern civilization is largely derived from fossil fuels, and as one declines so must the other. Yet if we argue on the basis of the amount of arable land, we arrive at a much larger potential figure for population.
It is impossible for both figures to be correct, but that based on arable land is more closely tied to any empirical evidence. Although there is no doubt a relationship between global oil production and global population, both in the past and in the future, that relationship may not be as simple as it looks. In other words, if annual oil production drops from its present 30 billion barrels down to 13 billion by the year 2030, as seems likely, that does not necessarily mean that population has to drop to that of the year 1965, i.e. 3 billion, when oil production was also 13 billion barrels.
The basic problem is that an estimation of population on the basis of the amount of oil production would conflict far too much with other, more-firmly established ways of estimating future population. A figure based on the ratio of population to arable land would be more reliable. Globally there are about 5 people per hectare of arable land, and this might be fairly close to a workable number, although this would still represent serious "overpopulation" in a world where agriculture is lacking fossil fuels.
Determining future global population on the basis of arable land involves multiplying the number of hectares of arable land by the number of people that could be supported per hectare. For example, in a study of corn (maize) production in Mexico that used only manual labor, David Pimentel (1984) claims that the average yield per hectare was 1,944 kg. He also notes that in a typical farm-based culture an adult burns about 1 million kilocalories ("calories") a year. Simplifying his various calculations considerably, we might say that these 1,944 kg of corn will provide about 9 million calories a year, or enough for 9 people. (There are uncertainties based largely on the question of what factors to be listed as input or output of calories. The term "net energy" sometimes suffers from a lack of clearly defined parameters.) By contrast, although there are many figures available on modern industrialized corn production, they tend to hover at around 6,000 kg or more. Crop yields from manual labor, in other words, are only a third of those found in agriculture that uses fossil fuels for machinery, fertilizer, pesticides, and so on.
Combining the figures on land use estimated separately by the CIA (annual) and by the FAO (Bot, Nachtergaele, & Young, 2000), we can say that in the entire world there are now about 1.5 billion hectares of arable land. This is about 10 percent of the world's total land area. If we multiply that figure of 1.5 billion hectares by the 9 people per hectare, we then apparently arrive at the notion that we can support 13.5 billion people without using fossil fuels -- far more, even, than our present population.
For various reasons, things are not quite that simple. Arable land is not evenly distributed in relation to the world's population, so some countries benefit more than others in that respect. Much of the arable land is not really used for that purpose. Land described as arable can actually be relatively unproductive, either because of natural factors such as mineral imbalance or harsh climate, or because it has been overworked for centuries. A certain amount of land must be left aside for fallowing in order to prolong the retention of nutrients and moisture. We must consider the fact that corn (maize), the above-mentioned crop, has a much higher yield in calories than most others, so these latter crops require more land per person. We must also take into consideration any rise in population beyond the present 7 billion.
When we include all these peripheral factors, we might need to start reducing the figures downward toward a practical maximum of about 4 people per hectare. If that is the case, it would seem we can still support 6 billion people with the world's arable land. However, about a third of the world's countries are already outside that 4:1 ratio; the worst areas are western Europe, the Middle East, most of southern and eastern Asia, and the islands of the Pacific. Most of sub-Saharan Africa does not have a low ratio of people to arable land, but hunger is nevertheless a problem there because agriculture is so badly organized, along with so many other economic and political matters. In view of all these qualifications and uncertainties, it might far too idealistic to be looking at future human population merely on the basis of arable land. In any case, it would provide us with numbers that could be applied only to the near future, not the more-distant future when many other elements of systemic collapse will be coming into play.
Even then, there is often not a direct relationship between "overpopulation" and "famine." For example, in the 1950s there were major famines, worse than those of later years, although the world population was only a third as large as it is today. For that matter, Ó Gráda (2007, March) claims that the worst famines in recent decades were in countries which rate not too badly in terms of population to arable land. Of more than 200 countries in the world, in terms of the ratio of population to arable land those mentioned by Ó Gráda as famine-prone would actually rate fairly highly: Angola 56th, Ethiopia 101st, Somalia 127th, Mozambique 81st, Afghanistan 64th, and Sudan 24th (CIA, annual).
The coming famines will certainly be a case of an imbalance between population and fossil fuels. Nevertheless, there will be other factors of importance, including government policy (as in the days of Stalin or Mao), warfare, ethnic discrimination, bad weather, poor methods of distribution, inadequate transportation, livestock diseases, and other variables that can turn mere hunger into genuine starvation. The fundamental issue, however, will be the amount of arable land.
Bot, A. J., Nachtergaele, F. O., & Young, A. (2000). Land resource potential and constraints at regional and country levels. World Soil Resources Reports 90. Rome: Land and Water Development Division, FAO. Retrieved from ftp://ftp.fao.org/agl/agll/docs/wsr.pdf
CIA. World factbook. (Annual). US Government Printing Office. Retrieved from https://www.cia.gov/library/publications/the-world-factbook/index.html
Ó Gráda, C. (2007, March). Making famine history. Journal of Economic Literature. Retrieved from http://www.ucd.ie/economics/research/papers/2006/WP06.10.pdf
Pimentel, D. (1984). Energy flows in agricultural and natural ecosystems. CIHEAM (International Centre for Advanced Mediterranean Agronomic Studies). Retrieved from http://www.ressources.ciheam.org/om/pdf/s07/c10841.pdf
Peter Goodchild is the author of Survival Skills of the North American Indians , published by Chicago Review Press. His email address is prjgoodchild[at] gmail.com
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