Surging population growth and climate change are driving the planet towards episodes of worsening hunger which only an overhaul of the food system will fix, a panel of experts said on Wednesday.

"In the 21st century, as we are now we've got a major set of converging threats," said John Beddington, a British professor who chaired a 13-member nine-month probe.

"There's population growth, unsustainable resource use and big pressures on humanity to transform the way that we use food," Beddington said in a teleconference.

"But it is intimately linked to water issues and energy issues -- and of course with the major issue of climate change."

Beddington said that in 2007-8, a surge in food prices drove 100 million people into poverty, and 40 million more followed them in the 2010-2011 spike.

"There is a real concern about hunger, and there are consequences at the level where food price increases cause instability," he said.

The so-called Commission on Sustainable Agriculture and Climate Change was set up in February by the Consultative Group on International Agricultural Research (CGIAR), an umbrella organisation funded by national governments, regional organisations and research foundations.

Drawing on published studies, the panel is offering guidance on how the world can be fed as its population rises from seven billion to more than nine billion in mid-century and diets shift to higher consumption of calories, fats and meat.

During this time, greenhouse gases emitted in past decades will have an inevitable effect on the climate system, adding to the risk of drought and flood.

"The challenge that's ahead of us globally is really quite hard even to comprehend," said Megan Clark, chief executive officer of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia.

"We must increase global food production by 2050 by some 30 to 80 percent and reduce our (carbon) emissions by half.

"To put it another way, as my children grow old over the next 60 years, we'll have to produce as much food as has been produced in human history and at the same time during that period, we will have to learn how to halve our emission rate from agriculture."

The panel released a "summary for policymakers," setting down seven recommendations. The full report will be issued early next year.

The proposals include a big focus on curbing waste through smarter supply chains, as roughly a third of food produced for human consumption is lost or wasted across the global food system.

Sustainable methods and support for poor, small farmers are also promoted. Costly over-use of fertilisers is cited as a problem, as are methods that wreck farmland.

"An estimated 12 million hectares (30 million acres) of agricultural land, and their potential for producing 20 million tonnes of grain, are lost each year to land degradation," said Lin Erda, director of the Research Centre of Agriculture and Climate Change at the Chinese Academy of Agricultural Sciences.

Asked what role genetically-modified crops should play, Clark said, "the commission didn't set out to pick winners with regard to agriculture."

"We looked at the major factors that would enhance resilience, productivity and sustainable use," said Clark. "We really came to the conclusion that you need to diversify responses, all the way through from organic to genetic."