Eating More With Less

A good guess is that food production will have to rise by 70% by 2050.  Several variables will drive this - - from population increases to the explosion of developing countries' megacities to changes in diet.  The output part of the equation is definable - - more babies, more people, more economic opportunities equals a somewhat linear demand for more food.

Historically our collective response to food output demands has been to look at our standard menu of input options.  The Big Three of reliable agricultural inputs has typically been land, water, and fertilizer.  But the reliable three have their own constraints and problems - - in fact, the standard inputs represent our trilemma in the context of the agricultural equation.

The February 26th-March 4th, 2011 issue of The Economist has a wonderful 14-page special report on the future of food.  Looking at just one of the trilemmas, water, the article highlights the following: 

According to Nestle's Peter Brabeck, roughly 4,200 cubic kilometres of water could be used each year without depleting overall supplies.  Consumption is higher, at about 4,500 cubic kilometres a year, of which agriculture takes about 70%.  As a result, water tables are plummeting.  The one in Punjab has fallen from a couple of metres below the surface to, in parts, hundreds of metres down.  The rivers that water some of the world's breadbaskets, such as the Colorado, Murray-Darling and Indus, no longer reach the sea.

By 2030, on most estimates, farmers will need 45% more water.  They won't get it.  Cities are the second-largest users of water, and those in the emerging world are growing exponentially.  They already account for half the world's population, a share that will rise to 70% by 2050.  In any dispute between cites and farmers, governments are likely to side with cities.  Agriculture's share of the world's water used to be 90%, so it has already fallen a long way.  It will surely decline further.

The reason water matters so much is that irrigated farming is so productive.  It occupies only one-fifth of the world's farmland but contributes two-fifths of the world's food output.  Rice, the world's most important crop in terms of calories, is mostly irrigated, and is especially sensitive to shortage of water, stopping growth at the first sign of getting dry.

Water problems will worsen both because irrigated areas will suffer disproportionately from the effects of climate change and because diets are shifting towards meat, which is "thirsty".  Arjen Hoekstra, of the University of Twente, says it takes 1,150-2,000 litres of water to produce 1 kg of wheat, but about 16,000 litres of water for 1 kg of beef.  As more people eat more meat, rising demand by farmers will collide with contracting water supplies.

With sustainability constraints from the classic Big Three, technology must play a much bigger role.  Technology that saves water, increases yields, decreases waste (30-50% of all food produced rots away uneaten) will become increasingly important.  Some optimal combination of biology and engineering will be needed - - scale and efficiency will drive both (and hopefully sufficiency will drive our cultural norms).  The old inputs of plentiful water and cheap energy will need to be reexamined - - climate change and energy prices will impact both.

Like Robert Louis Stevenson wrote, "Sooner or later, we sit down to a banquet of consequences."  A population of nine billion people will produce a whole new set of consequences that engineers will be required to sit down at the table to consider.