In the 1960s many experts predicted mass famine in Asia. A bestselling 1968 book warned that hundreds of millions would starve in the coming decade, and India, after two failed monsoons, depended on shipments of American wheat. Famine on that scale never came. A large part of the reason was a set of changes in farming that became known as the Green Revolution.

Short wheat and miracle rice

The story usually starts in Mexico in 1944, where a program backed by the Rockefeller Foundation and the Mexican government brought in a young American plant scientist, Norman Borlaug. Borlaug spent years crossing thousands of wheat varieties, shuttling between two growing regions so he could raise two generations a year. His key step was to breed in dwarfing genes from a Japanese variety. Ordinary tall wheat, given heavy fertilizer, grows tall and top-heavy and falls over, a problem called lodging. Semi-dwarf wheat had short, stiff stems that could carry heavy heads of grain without collapsing. It also resisted rust, a fungal disease, and grew well across many latitudes.

In 1966 the International Rice Research Institute in the Philippines released IR8, a semi-dwarf rice soon nicknamed miracle rice, which could double yields when well watered and fertilized. Borlaug received the Nobel Peace Prize in 1970 for his part in feeding a hungry world.

A package, not a seed

The new seeds did not work alone. Green Revolution varieties delivered high yields only with irrigation, fertilizer and pest control. They were bred to turn extra nitrogen into grain instead of straw, so their advantage appeared only when farmers applied much more fertilizer, made by the Haber-Bosch process. Governments supplied credit, subsidized inputs, built irrigation and guaranteed prices. In India, the agricultural scientist M. S. Swaminathan and ministers in New Delhi pushed the program hard after the droughts of 1965 and 1966. India's wheat harvest more than doubled within about six years, and the country stopped depending on food aid.

Worldwide, cereal production more than tripled between the early 1960s and the 2010s, while the area planted grew far more slowly. Supporters stress what this meant for nature. Borlaug and others argued that higher yields spared land from the plow: feeding today's population at 1960s yields would have required clearing vast additional areas of forest and grassland.

The critics

The Green Revolution has drawn strong criticism, and the best critics do not deny the extra grain. They question its costs and who bore them. The first concern is environmental. Heavy irrigation drew down groundwater, salted soils and drained rivers. Fertilizer runoff polluted water. Pesticide use rose, sometimes with serious harm to farmworkers. Planting a few high-yielding varieties over huge areas narrowed the genetic base of crops, which can leave them exposed to a single new disease.

The second concern is social. Farmers who could afford irrigation and inputs gained most at first, and in some regions larger farmers bought out smaller ones. Debt became a burden when crops failed or prices fell. The Indian scholar and activist Vandana Shiva, in a 1991 book, argued that the program made farmers dependent on purchased seed and chemicals and left soils and communities poorer. A third concern is diet: as wheat and rice spread, farmers grew fewer pulses and millets, which are rich in protein and minerals.

Finally, sub-Saharan Africa largely missed the first Green Revolution. Its main crops, such as sorghum, cassava and millet, got less research attention; most farming relied on rain rather than irrigation; and roads and markets were thin. Efforts to raise African yields have continued since, with debate over whether they should follow the Asian model or take a different path.

Worked example: Punjab

The Indian state of Punjab was the showcase of the Green Revolution. Its flat land, canals and enterprising farmers made it ideal for the new wheat, and later rice. By the 1970s Punjab, with a small fraction of India's land, was supplying a large share of the grain the national government bought to feed the cities and the poor. Farm incomes rose and rural poverty fell.

Fifty years on, Punjab also shows the costs. Rice is a thirsty crop, and Punjab is not naturally a rice region. Subsidized electricity let farmers pump groundwater freely, and in much of the state the water table has been falling year after year. Burning rice stubble after harvest adds to severe autumn smog across northern India. Many farmers carry heavy debts, and rural distress has been tied to a wave of suicides. Government price guarantees for wheat and rice make it risky for farmers to switch to other crops.

Both camps can claim Punjab. It is evidence that science, seeds and public investment can end hunger fast, and evidence that a system built for one decade's emergency can become a trap for the next.