Wednesday, August 19, 2015

Statistics and the Future of Food Production

An interesting piece of analysis by Doug Boucher who is an expert in preserving tropical forests to curtail global warming emissions. He has been participating in United Nations international climate negotiations since 2007 and his expertise has helped shape U.S. and U.N. policies. He holds a Ph.D. in ecology and evolutionary biology from the University of Michigan.

“We will need to produce at least 60% more food in 2050”, a statement that has been repeated over and over again in speeches and on websites explaining why it’s necessary to raise agricultural production, whether by using GMOs, clearing forests, or totally revolutionizing the global food system. The wording may vary (sometimes it’s 70% or “doubling” or) as does the exact phrasing (often it includes phrases like “to feed our rapidly growing population”) but the message is always one of urgency and alarm.

What exactly is the analysis that this prediction is based on? Naively, one might think that you’d measure food by weighing it, so that the 60% figure meant 60% more kilograms, pounds or tons. A little more sophisticated approach could be to look at the amount of energy in the food, which would mean measuring it in calories. This would take into account the fact that some foods (e.g coffee or celery) have very little energy, while others (e.g. rice or pork) have considerably more, so that their weights are a good reflection of their value for human growth and survival. Other possibilities could include weighting foods by their protein content, or other important nutrients such as phosphorus, calcium or vitamins.


Rather it turns out that none of these but instead the unit of measurement for the calculation, is dollars. What does it mean say that the global population will need to consume many more dollars of food in 2050? The answer is that this is an economic projection, not an estimate of need.

The authors who did the calculation – FAO experts Nikos Alexandratos and Jelle Bruinsma, for successive publications in 2006, 2009, 2012 and 2013 – made this quite clear. Here is a quote that is repeated verbatim in their 2006 and 2012 reports:
“The figures we use refer to the aggregate volume of demand and production of the crop and livestock sectors. They are obtained by multiplying physical quantities of demand or production times price for each commodity and summing up over all commodities.”

And, in more detail:
“The figure 70 percent from average 2005/7 to 2050 has been widely quoted. It is important to realize what it means: when speaking of growth rates of aggregate agricultural production or consumption, it matters what units are used in the measurement of change, in particular whether quantities of the different commodities are just aggregated in physical units …. or aggregated after making them homogeneous by multiplying each quantity with an appropriate weighting factor and summing up. The weights often considered are food-specific calorie content of each commodity (e.g. kcal per kg.) or price. ….This study uses the international dollar prices of 2004/06 …. the physical weight aggregation would not make sense and the same goes for calorie weights.”

So the authors are quite clear: this is a projection, in economic units, of the global demand for food. It weights foods not by how many calories or how much protein they contain, but by their prices.

What is the consequence of this?

It turns out that the prices of different kinds of foods, in dollars per kilo or per pound are very different. Here, for example, were the U.S. export prices of different foods in July 2005, indexed by taking maize (corn) as equal to 1.0:
Beef     33.0
Pork    17.0
Poultry 6.7
Wheat  1.9

In other words, this way of doing the calculations counts meat, and particularly beef, way out of proportion to its calorie or protein content. So that as global diets shift towards more meat as incomes increase, the projection of “need,” done in dollar terms, will go up.

FAO 2006: “At the world level, the growth of demand for all crop and livestock products is projected to be lower than in the past, 1.5 percent p.a. in the period 1999/01-2030 and 0.9 percent for 2030-50 compared with rates in the area of 2.1-2.3 percent p.a. in the preceding four decades.”

FAO 2009: “The projections show that feeding a world population of 9.1 billion people in 2050 would require raising overall food production by some 70 percent between 2005/07 and 2050.”

FAO 2012: “…global production in 2050 should be 60 percent higher than that of 2005/2007.”

CGIAR/FAO 2013: “FAO estimates that global agricultural production in 2050 will need to increase by at least 60 percent relative to 2006, a growth rate of just less than 1.2 percent annually.”

The Economist 2011: “ demand for food will rise about 70% in the 44 years from 2006 to 2050, more than twice as much as demand for cereals.” (The Nine Billion-People Question, 26 February 2011, p. 4)

National Geographic 2014: “By 2050 the world’s population will likely increase by about 35%…. To feed that population, crop production will need to double.” (Feeding Nine Billion, May 2014, p. 45)

The false conclusion is that in order to feed the world’s growing population, more food in the next 50 years than in the past 10,000, during a 40-year period  in which global population is projected to increase by less than 40%? Hard to believe, if it’s kilos or calories of food – but perhaps the case if you measure food in dollars. The predictions are all dollar figures, not an actual measure of need.

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