Irrigated area is shrinking in the Middle East, notably in Saudi Arabia, Syria, Iraq, and possibly Yemen. In Saudi Arabia, which was totally dependent on a now-depleted fossil aquifer for its wheat self-sufficiency, production is in a freefall. From 2007 to 2010, Saudi wheat production fell by more than two thirds. By 2012, wheat production will likely end entirely, leaving the country totally dependent on imported grain.
The Arab Middle East is the first geographic region where spreading water shortages are shrinking the grain harvest. But the really big water deficits are in India, where the World Bank numbers indicate that 175 million people are being fed with grain that is produced by overpumping. In China, overpumping provides food for some 130 million people. In the United States, the world's other leading grain producer, irrigated area is shrinking in key agricultural states such as California and Texas.
The last decade has witnessed the emergence of yet another constraint on growth in global agricultural productivity: the shrinking backlog of untapped technologies. In some agriculturally advanced countries, farmers are using all available technologies to raise yields. In Japan, the first country to see a sustained rise in grain yield per acre, rice yields have been flat now for 14 years. Rice yields in South Korea and China are now approaching those in Japan. Assuming that farmers in these two countries will face the same constraints as those in Japan, more than a third of the world rice harvest will soon be produced in countries with little potential for further raising rice yields.
A similar situation is emerging with wheat yields in Europe. In France, Germany, and the United Kingdom, wheat yields are no longer rising at all. These three countries together account for roughly one-eighth of the world wheat harvest. Another trend slowing the growth in the world grain harvest is the conversion of cropland to nonfarm uses. Suburban sprawl, industrial construction, and the paving of land for roads, highways, and parking lots are claiming cropland in the Central Valley of California, the Nile River basin in Egypt, and in densely populated countries that are rapidly industrializing, such as China and India. In 2011, new car sales in China are projected to reach 20 million -- a record for any country. The U.S. rule of thumb is that for every 5 million cars added to a country's fleet, roughly 1 million acres must be paved to accommodate them. And cropland is often the loser.