Oxfam called on Tuesday for an overhaul of the world’s food system, warning that in a couple of decades, millions more people would be gripped by hunger due to population growth and climate-hit harvests.

A “broken food system” means that the price of some staples will more than double by 2030, battering the world’s poorest people, who spend up to 80 percent of their income on food, the British-based aid group predicted.

“The food system is buckling under intense pressure from climate change, ecological degradation, population growth, rising energy prices, rising demand for meat and dairy products and competition for land from biofuels, industry, and urbanization,” Oxfam said in a report.

It added: “The international community is sleepwalking into an unprecedented and avoidable human development reversal.”

Noting that some 900 million people experience hunger today, Oxfam said the tally of misery could rise still further when a “perfect storm” struck a few decades from now.

By 2050, the world’s population was expected to rise by a third, from 6.9 billion today to 9.1 billion. Demand for food would rise even higher, by 70 percent, as more prosperous economies demanded more calories.

But by this time, climate change will have started to bite, with drought, flood and storms affecting crop yields that, after the “green revolution” of the 1960s, had already begun to flatline in the early 1990s.

The price of staple foods such as corn, also known as maize, which has already hit record peaks, will more than double in the next 20 years, it predicted.

“In this new age of crisis, as climate impacts become increasingly severe and fertile land and fresh water supplies become increasingly scarce, feeding the world will get harder still,” Oxfam chief Jeremy Hobbs said.

The report, Growing a Better Future, trails a campaign for reform that Oxfam is launching in 45 countries, supported by former Brazilian president Lula Luiz Inacio Lula da Silva, South African Nobel laureate Desmond Tutu and actress Scarlett Johansson.

Solutions envisaged by Oxfam focus on cutting out waste, especially of water, and to encourage the growing of food in a sustainable way.

The “Western” lifestyle — characterized by over consumption and emphasis on beef and dairy which kilo for kilo (pound for pound) use up far more natural resources than cereals — is given a hammering.

“In more than half of industrialized countries, 50 per cent or more of the population is overweight, and the amount of food wasted by consumers is enormous — quite possibly as much 25 per cent,” said Oxfam.

The report also calls for prising open closed markets and ending the domination of commodities and seeds trade by a handful of large corporations.

Small farms — traditionally dismissed as a hindrance to food productivity — could in fact drive the renaissance in yield with the help of investment, infrastructure and market access, it argued.

Just as important, said the report, is to set up new global governance to tackle food crises, including the creation of a multilateral food bank.

“During the 2008 food price crisis, cooperation was nowhere to be seen,” lamented the report, saying the disarray ignited a “grab” for agricultural land in Africa by parched countries in the Gulf and elsewhere.

“Governments were unable to agree on the causes of the price rises, let alone how to respond. Food reserves had been allowed to collapse to historic lows,” it said.

“Existing international institutions and forums were rendered impotent as more than 30 countries imposed export bans in a negative-sum game of beggar-thy-neighbour policy making.”