Do we have lots of spare agricultural land?

This question is prompted by a comment in Wayne Grudem’s chapter on the Environment in Politics According to the Bible which I’ve browsed before, but thought I ought to look at more thoroughly as the man himself is visiting Tyndale House where I work.

Grudem is a significant theologican of the American Evangelical Right, and gets a lot of readership in that community. He is on the advisory board of the climate-sceptic Cornwall Alliance, authors of An Evangelical Declaration on Climate Change, and the chapter credits Cal Beisner, its head, heavily. So this chapter (and the book generally) provides a helpful insight into the mindset of this community.

It would be an instructive exercise for someone to analyse his environmental chapter in detail and assess the claims and theology made in it. I already have several pages listing points I either disagree with or struggle with. I’ve also found reading Stephen Grey’s blog helpful. He’s a Christian member of the Green Party has gone through most of the book commenting on it (see, for instance this post) in more general terms.

For this post, I want to evaluate just one claim. Grudem writes:

But will we run out of land to grow enough food to feed the world’s population? No, not at all. Out of the total ice-free land surface of the earth, about 24% is “arable”–that is, it could produce an acceptable level of food crops. That is about 3.2 billion hectares… But this potential crop land is more than three times the area actually used for growing crops in any given year at the present time? Roger Revelle, former director of Harvard University’s Center for Population Studies, estimated as far back as 1984 that … it could feed about 3 billion people “at an average intake of 2350 kcal per day.” (pages 336-7)

The other figures in this section also come from a chaper Revelle wrote in 1984. Perhaps you, like me, found them rather surprising – aren’t we told land is in short supply? So I cross-referenced against a UN Food and Agriculture Organisation (FAO) report from 2003: World Agriculture: Toward 2015/2030. I appreciate this is rather old (I misread the date initially) but would have been accessible to Grudem when writing his book (published in 2010).

The FAO use a different definition of arable, i.e., the land actually in use for growing crops, and give the figure of 1.57 billion hectares (Bha) which broadly agrees with Revelle’s figure. What are we doing with other 90% of the land. A small proportion (0.15 Bha) is for permanent crops such as orchards and plantations, but a large amount (3.36Bha) forms permanent pastures. Forests form over 30% of world area (4Bha).

Could this be converted to cropland? In theory, the FAO reckon another 2.7Bha could be used, but about a third of this is so marginal as not to be useful. The remaining 1.8Bha is usable but has problems, including:

  • 90% of it is in Latin America and sub-Saharan Africa, with virtually none in China and the Middle East where we would like it. It isn’t clear whether this land is even in the right parts of sub-Saharan Africa though.
  • Considerable investment in infrastructure is required to be able to use it effectively (like get the food out).
  • Much is of pretty low quality or not suitable for crops which can be exported, or wanted – for instance much spare land in DR Congo is good for cassava but not wheat.
  • About 60% is already in use for things we want (forests 45%, protected land 12%, human settlements 3%).

Their estimate is thus that by 2030, the global South will increase its arable area by only 120 million hectares, or about 6% of what Revelle reckons. They don’t give a productivity figure, but Revelle’s estimate of feeding 35 billion would be too high even if the amount of land was there – he is making unreasonably high assumptions of the quality of the land, and (implicitly) assuming a pure vegetarian diet which I don’t think Grudem would want anyone to have imposed on them given his broadly libertarian attitude to government. It also disregards the rather scary statistics for land degradation and the risk of land-loss to sea level rise (which to be fair are likely to be reasonably small before 2030, the end-date for the FAO report, but will increase radically thereafter.)

Not only that, but Revelle’s 2350kcal daily intake is contradicted in Grudem’s book by a graph on the following page (coincidentally taken from a different FAO report also published in 2003) which gives daily calorie intake per capita in 2010 at over 2800kcal, and increasing. Finally, Revelle seems an odd choice of source, both given the date, and his lack of expertise as an agronomist – he was a climate scientist and geologist.

So some conclusions:

  • Grudem’s claim that we use what, to me, was a comparativel low proportion of the world’s land for growing crops, is correct.
  • But advocating we can solve food crises by just expanding onto the rest is naive, with the possible exception of parts of sub-Saharan Africa. The conventional view that we are using almost all the land we reasonably can seems vindicated.
  • In any case, using this comparatively marginal land requires considerable energy use and infrastructure investment, which we are  still short of. (Grudem would solve this by assuming continued massive economic growth, but he is not taking into account the consequence of oil price increases – his economics need to wait for another post.)
  • Grudem puts a lot of weight on a calculation done 25 years previously by a non-expert while ignoring a more recent UN report that says something different. Poor scholarship on this point at least.




Filed under Books and resources

3 responses to “Do we have lots of spare agricultural land?

  1. Ann Parker

    Zero Carbon Britain which ran an online conference a month or so back and now has the information availaable through the Alt energy centre, CAT, had a good presentation on how we could make better use of land in this country

    • Colin Bell

      Ann, thanks for this. Going to make a follow-up post including this and some other information I’ve been sent.

  2. Pingback: Agricultural land revisited | Sustainability in Crisis

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