Cod caught off Norway is shipped to China to be turned into filets, then shipped back to Norway for sale. Argentine lemons fill supermarket shelves on the Spanish Citrus Coast as local lemons rot on the ground. Half of the peas in Europe are grown and packaged in Kenya.

In the US, FreshDirect.com proclaims kiwi season has expanded to “All year!” now that Italy has become the world’s leading supplier of the national fruit of New Zealand, taking over in the Southern Hemisphere’s winter.

Food has moved around the world since Europeans discovered tea in China, but never at the speed or in the amounts it has over the last few years. Consumers in not only the richest nations but also, increasingly, the developing world expect food whenever they crave it, with no concession to season or geography.

Increasingly efficient global transport networks make it practical to bring food before it spoils from distant places where labour costs are lower. And the penetration of megamarkets in nations from China to Mexico with supply and distribution chains that gird the globe — like Wal-Mart, Carrefour and Tesco — has accelerated the trend.

But the movable feast comes at a cost: pollution, especially carbon dioxide, from transporting the food.
Under longstanding trade agreements, fuel for international freight carried by sea and air is not taxed. Now, many economists, environmentalists and politicians say it is time to make shippers and shoppers pay for the pollution, through taxes or other measures.

“We’re shifting goods around the world in a way that looks really bizarre,” said Paul Watkiss, an Oxford University economist who wrote a recent European Union report on food imports. He noted that Britain, for example, imports — and exports — 15,000 tonnes of waffles, and similarly exchanges 20 tonnes of bottled water with Australia. More important, Watkiss said, “we are not paying the environmental cost of all that travel.”

Europe is poised to change that. The European Commission announced this year that all freight-carrying flights into and out of Europe would be included in the European emissions trading programme by 2012, meaning that permits will have to be purchased for the pollution they generate.

Under a little known international treaty called the Convention on International Civil Aviation, signed in Chicago in 1944 to help the fledgling airline industry, fuel for international travel and transport of goods, including food, is exempt from taxes levied on fuel for trucks, cars and buses. There is also no tax on fuel used by ocean freighters.

Proponents say ending these breaks could help ensure that producers and consumers pay the environmental cost of increasingly well-travelled food. The food and transport industries say the issue is more complicated. The debate has put some companies on the defensive, including Tesco, the largest British supermarket chain, known as a vocal promoter of green initiatives.

Some studies have calculated that as little as three per cent of emissions from the food sector are caused by transportation. But Watkiss, the Oxford economist, said the percentage was growing rapidly. Moreover, imported foods generate more emissions than generally acknowledged because they require layers of packaging and, in the case of perishable food, refrigeration.

Proponents of taxing transportation fuel say it would change the economic calculus. The European Union has led the world in proposals to incorporate environmental costs into the price consumers pay for food at the market.

Switzerland, which does not belong to the EU, already taxes trucks that cross its borders.

The problem is measuring those emissions. The fact that food travels farther does not necessarily mean more energy is used. Some studies have shown that shipping fresh apples, onions and lamb from New Zealand might produce lower emissions than producing the goods in Europe, where for example, storing apples for months would require refrigeration.

Shippers have vigorously fought the idea of levying a transportation fuel tax, noting that if some countries repealed those provisions of the Chicago Convention, it would wreak havoc with global trade, creating an uneven patchwork of fuel taxes. It would also give countries that kept the exemption a huge trade advantage.

Box Fresh Organics, a popular British brand, for example, advertises that 85 per cent of its vegetables come from the British Midlands. But in winter, in its standard basket, only the potatoes and carrots are grown in Britain. The grapes are from South Africa, the fennel is from Spain and the squash is from Italy.

Retailers today could not survive if they failed to offer such variety, said Ed Moorehouse, a consultant to the food industry in London. “Unfortunately,” he said, “we’ve educated our customers to expect cheap food, that they can go to the market to get whatever they want, whenever they want it. All year. 24/7.”