Norman Borlaug, the 1970 Nobel Prize winner who developed more productive crop varieties to better feed the world, warned that the battle against hunger could ebb “if we become complacent and relax our efforts.”

For much of this decade, world supplies of corn, soybeans, wheat and rice have trailed their consumption. Not anymore.

Borlaug’s plant-breeding accomplishments and the related increase of fertilizers helped Mexican farmers boost their wheat yields sixfold in almost 20 years. His successor at Mexico’s International Maize and Wheat Improvement Center, Hans-Joachim Braun, cites modern agriculture’s dependence upon dwindling groundwater supplies and agricultural land base as being “in no way sustainable.”

The world’s population is projected to increase by 43% (3 billion) by 2085, according to the U.N.

Oxfam, the international relief consortium, recently predicted that food prices would more than double by 2030 from today’s level.

Monsanto has set the goal of developing

seeds that will double the yields of corn, soybeans and cotton by 2030 and require 30% less water, land and energy to grow.

We’ve doubled the world’s food production several times before in history, says Jonathan Foley, a University of Minnesota researcher. “The last doubling is the hardest. It is possible but it’s not going to be easy.”

James Specht, a soybean genetics expert at the University of Nebraska, quoted in the New York Times, said he doubted this could be done. "Seeing an exponential change in the yield curve is unlikely."

Recent droughts and floods have put agriculture on the front page, and speculation abounds on how long we can take full stomachs for granted.

If global warming is confirmed to be a continuing trend, the findings of two economists are alarming. Wolfram Schlenker of Columbia University and Michael Roberts of North Carolina State University have shown that corn and soybean yields fall sharply when exposed to temperatures above 84 and 86 degrees, respectively. “That was looking at yields 1950-2005,” Schlenker says. “The big challenge going forward is whether we can develop more heat-resistant crops.”

Although extra atmospheric carbon dioxide is thought to boost crop yields, new University of Illinois research finds that its bonus effect does not offset the projected yield decline of high temperatures or low rainfall. “We’re starting to believe that the positives of CO2are unlikely to outweigh the negatives of other factors,” says Illinois researcher Andrew Leakey.