“The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction, and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague advance in terrific array, and sweep off their thousands and tens of thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world.”

So proclaimed Thomas Malthus (1766–1834) in his seminal An Essay on the Principle of Population. He became Britain’s first professor of history and political economy in 1805 and a most influential thinker. In his view, vice and misery explained population oscillations. Provide humans with any excess of food and they would copulate unrestrainedly—vice—until their numbers exceeded the food supply. Many would then starve—misery—restoring the equilibrium. He saw that population had the capacity to grow exponentially, but contended that the food supply only increased lineally. If living standards deviated from bare subsistence, vice or misery would set in.

Malthus witnessed the dawn of the industrial revolution that triggered the burgeoning human population growth that continues to this day. The world’s population was estimated at 200 million at the time of Christ, one billion in 1804, reached two billion in 1927, three in 1959, four in 1974, five in 1987 and six in 1999.

But Malthus was not right on the mark. Population increases in recent times have arisen “not because human beings suddenly started breeding like rabbits but rather because they stopped dying like flies”, as one sage put it. Improvements in public health—clean water, sewage disposal, vaccinations and so forth—have lowered infant mortality and prolonged life for the elderly. Once women were educated and gained access to birth control, they opted for small families and more prosperity. And as education and affluence increase around the globe, population growth is projected to decline and stabilise, probably at 9–10 billion in another 40–50 years, according to United Nations estimates.

But the problem of balancing food and population that Malthus recognised remains with us. Famines and wars are still rampant, which modern media make more apparent and poignant than ever before.

Yet surprisingly, despite the unparalleled growth in the abundance of humans over the past 150 years and the pessimism of people such as Paul Ehrlich and of the Club of Rome in the 1960s and 70s, the global food supply has more than kept pace with population. In 1959, world grain production was 818 million tonnes, in 1974 it was 1.2 billion tonnes, in 1987 it was 1.6 billion and in 1999 it was 1.87 billion. Grains, including those fed to livestock, constitute more than half of the calories in the human diet. At present, enough calories are produced to comfortably feed everyone in the world, but a large proportion of grain is diverted into feeding animals for meat production, and now into biofuels.

Food distribution is also a major problem, and likely to remain so. Some 25 per cent of people are undernourished. How will we fare in a world with a population of 10 billion?

There are other issues. As people become more affluent, they want more meat, eggs and milk products, higher-quality food and more of it. Taking account of this trend, food demand is projected to increase 56–120 per cent by 2050 compared with the output in 2000. But food producers will have to contend with increasing climate instability, lower rainfall, salinisation of many irrigated soils and increasing loss of arable land by erosion. And of course, there is virtually no more unused land with potential for agriculture.

Indeed, agriculture is already seen by some as the largest threat to biodiversity and the environment. It occupies more land than any other human activity and uses much of the world’s diminishing supplies of fresh water.

The Green Revolution, which introduced high-yielding crop cultivars, chemical fertiliser, herbicides, pesticides, irrigation and large-scale farming in the latter half of the 20th century, has been largely responsible for the increase in food production. Could genetically modified organisms (GMOs) hold the key to getting us out of the next food fix? Others say more sustainable farming is the only way to go and that that means organic. Between these poles lies conventional farming—and New Zealand agriculture.