Julian Cribb, from the University of Technology Sydney, told delegates on Monday at the National Farmers' Federation congress in Brisbane that the world's food supply was already precariously balanced and demand would rise by 110 percent by 2050.

"Sustaining food production through the mid-century peak in human demand and numbers is the challenge of our age," Cribb said.

"It is more urgent even than global warming or the economic crisis."

Already over 1.2 billion people go hungry every day - the greatest number in history - and food prices are rising, he noted.

"The modern diet and the way we produce it are not sustainable," he said. "The farming challenge facing the current generations is immense."

Cribb indicated the challenge was to double the global food supply using much less water and land, without fossil fuels, in an increasingly erratic climate.

By 2050, 40 percent of the world would be in serious drought and the world was losing one percent of its agricultural land each year.