Here's a piece I wrote for a Times supplement published yesterday in print, not available online.
In the twentieth century, the world population quadrupled. By the 1960s, it was growing at 2% a year. Yet, unlike the nineteenth century when the prairies, pampas and steppes had been brought under the plough, little new land was available to grow human food. Some in the western world began to suggest that food aid to the poor was only making the population problem worse. The ecologist Paul Ehrlich forecast famines `of unbelievable proportions' by 1975; the chief organizer of Earth Day, 1970, said it was `already too late to avoid mass starvation'; a professor in Texas said that by 1990 famines would be devastating `all of India, Pakistan, China and the Near East, Africa'.
Why did this not happen? Why was India a net exporter of food by the mid 1970s? Why did China never revisit the horrors of Mao's famines? Why has famine virtually disappeared from Africa except where foolish dictators cause it? Why has the growth rate of the world population halved to 1%?
It is not fully true to say that the answer to these questions is `Norman Borlaug', but it is not entirely false either. Borlaug was an American biologist who bred new varieties of wheat in Mexico in the 1950s. By deliberately crossing `dwarf' varieties from Japan with other strains, he soon had a wheat plant that not only put more of its energy into grain and less into stalk, but also could withstand heavy applications of synthetic fertilizer without collapsing. Borlaug then fought, like a tiger, against bureaucratic obstacles to get his wheat varieties tested in India and Pakistan and to open those countries up to fertilizer imports. The result was a rapid transformation of wheat yields on the Indian subcontinent, known as the green revolution, which was then emulated elsewhere and with different crops.
Consider the effect of this not just on famine, but on wilderness. We currently feed nearly seven billion people by farming about 38% of the land surface of the planet. If we wanted to feed that many people by using the techniques, varieties and - mostly organic - fertilizers of the 1950s, we would need to cultivate roughly 84% of the land surface. There goes the rain forest, the national parks, the wetlands. The intensification of agriculture has saved wilderness.
It has also defused the population bomb. The best way of cutting population growth - paradoxically - is by preventing famine. When child mortality drops, people have fewer babies. Birth rates are now dropping so fast that the population may not even go up by 50% this century, whereas it rose by 300% in the last century. By 2075, perhaps sooner, world population will probably be falling.
Can we feed the nine billion people who will then exist on earth? Yes. We trebled yields in the last 60 years without taking extra land under the plough. If we did that again - by getting fertilizer to farmers in Africa and central Asia, by cutting losses to pests and droughts through ever more subtle genetic manipulation, by improving roads and encouraging trade - then we could feed nine billion better than we feed seven billion today. And still retire huge swathes of land from farming to rainforest and other forms of wilderness.
The two most effective policies for frustrating this uplifting ambition are: organic agriculture and renewable bio-energy. Organic farming means growing your nitrogen fertilizer rather than fixing it from the air. That requires more land, either grazed by cattle or planted with legumes. The quickest way to destroy what wilderness we have left is to go organic. Bio-energy (growing crops to make fuel or electricity) takes food out of the mouths of the poor. In 2010, the world diverted 5% of its grain crops into making fuel, displacing just 0.6% of oil use yet killing an estimated 192,000 people by tipping them into malnutrition through higher food prices. We should stop such madness now.