A report by the Food Climate Network, based at the UK's University of Surrey, wants to bring back food rationing. If we don't limit ourselves to four modest portions of meat and one liter of milk a week, it says, there's no way we'll avoid run-away climate change. And we should seriously reduce low nutritional value food like alcohol, candies and chocolate.

Instead we should buy locally and seasonally, cook in bulk, cover our pots with lids or use pressure cookers, walk to the stores and convert to internet shopping. Encouraging people to change their habits voluntarily isn't enough, say the authors of this four-year study, considered the most thorough yet.

"Food is important to us in a great many cultural and symbolic ways, and our food choices are affected by cost, time, habit and other influences," the report says. "Study upon study has shown that awareness-raising campaigns alone are unlikely to work, particularly when it comes to more difficult changes."

Governments, it urges, should apply caps on greenhouse gas emissions and carbon pricing to ensure changes are made.  Alarmed by the amount of greenhouse gases from livestock, it recommends cutting meat consumption by at least half, and making sure animals are fed as much as possible on grass and food waste which can't be eaten by humans.

The UN and other bodies have recommended that developed countries should reduce total emissions by 80 percent by 2050. Are we likely to take any notice? When Rajendra Pachauri, the head of the United Nations intergovernmental panel on climate change, urged people recently to have at least one meat-free day a week, he sparked a global debate. That's a euphamism for steaming argument.