The trouble is that rainfall is less reliable, especially in the Northern Hemisphere. Records over the past century show that peaks and troughs in rainfall, particularly north of the equator, have become sharper and bigger. It's either deluge or drought.
Years of drier weather in the U.S. plains have steadily reduced beef herds, with the number of calves down 8% since 2006 as pastures have dried out and feed costs have rocketed.
A return to food riots?
Thanks to new crop hybrids, irrigation and other technological advances, global food production has consistently risen despite the vagaries of weather patterns. But food security is skewed toward the developed world. In poorer countries, where a larger part of family income is spent on food, unpredictable harvests and volatile food prices can lead to social unrest.
A sudden increase in the price of staples in 2007 and 2008, in part due to adverse weather, led to riots in about a dozen countries.
According to Colin Chartres, who heads the International Water Management Institute, we can expect more extreme weather.
"In monsoon climates, we expect later onset of the monsoon, heavier rainfall, shorter monsoon duration and so on. More flooding is to be expected, as are more droughts. Forecast temperature increases due to climate change will mean higher rates of evaporation," Chartres said during a visit to Kazakhstan.
It might seem the perfect storm: the prospect of less reliable harvests, a growing world population and demand for food projected by the United Nations Food and Agriculture Organization to rise 70% by mid-century. But the experts say there are many ways we can mitigate the effects.
"More than one-fourth of all the water we use worldwide is taken to grow over 1 billion tons of food that nobody eats," said Torgny Holmgren, director of the Stockholm International Water Institute.
Most of it is wasted in developed countries where food is plentiful, some by poor storage in developing countries.
In its latest report (PDF), the institute says the focus should be on "energy efficiency in food production, including getting more 'crop per drop,' " and "how to reduce the 30-50% of food that is lost and wasted from harvest to consumption."
At least part of the answer may come from new small-scale irrigation techniques. Chartres said that low-cost sustainable techniques can double yields for small farmers.
"These systems have been based on cheap pumps that run on electricity or diesel," he said. "When coupled with drip irrigation, they can be very water-efficient."
Half a million smallholders in Ghana alone use such techniques, and in Burkina Faso they have helped almost triple vegetable production over the past 15 years.
But financing remains a problem.
"In some parts of Africa, even the $500 needed to purchase basic equipment is beyond the means of small farmers," Chartres said. "Sometimes, entrepreneurs buy a pump and take it round to farmers on a bicycle."
Ali Kachelo in Pakistan's Sindh province knows similar problems. He says mismanagement of the antiquated irrigation system has made efficient farming much more difficult.
"The ministry of agriculture is supposed to aid in having farmers learn and implement new irrigation methods but has not been very helpful," he said.
Kachelo says that he is learning how to employ overhead sprinklers to help conserve water but that most irrigation methods have not been updated since the British ruled Pakistan.
"We rely heavily on our reservoirs (which hold meltwater from the Himalayas), but poor management has caused them to dry up."