The continuing failure to agree worldwide measures to limit greenhouse gas emissions has seen an epidemic of piecemeal interventions at the level of national governments. Some of these well-intentioned schemes will make little difference but luckily have limited costs. Others impose substantial burdens and have been manipulated shamelessly by rent-seeking economic interests in pursuit of corporate welfare – the subsidy-farmers in the renewable energy ‘‘industry’’ in Ireland are merely the most egregious local example.

The least-cost policy to cut emissions would be a worldwide tax on the consumption of carbon-intensive products, pitched at a level designed to achieve the emission reductions which the scientific evidence indicates. Such a tax, the proceeds of which would remain with national governments, would be paid mainly by wealthier consumers in the developed world. Instead, individual countries pursue national targets for emissions with varying degrees of enthusiasm, little success and unmeasured costs. Meanwhile, some products and activities which generate emissions are taxed heavily in many countries, some are taxed lightly or not at all and some are even subsidised. Peat-fired electricity in Ireland and auto-fuel at under 20c/l in parts of the Middle East are glaring examples.

Companies in many sectors, conscious of widespread concern about global warming, have spotted a marketing opportunity: promote your product as environmentally sustainable and the public will warm to your product. Persuade people that food imported over long distances can be substituted with homegrown alternatives and you can appeal both to environmental angst and to economic nationalism.

Exports

For any country reliant on agricultural exports, the growing deployment of the ‘‘food miles’’ theme in food advertising and promotion is short-sighted and irresponsible. It is also demonstrable nonsense in economic terms. The food miles fairy story goes like this. Your local supermarket offers food products imported from distant suppliers. These items could be produced locally (presumably on land currently a wilderness and by farmers currently on holidays). Hey presto, there is less need for freight transport, carbon emissions are reduced and with one brave bound the planet is saved.

International trade happens for good reasons, including differences in labour and capital endowments and in climate. It is technically possible to grow bananas in Donegal but wiser to stick with potatoes and leave the banana business to Guatemala. The food miles argument is a little more sophisticated: it is possible for Britain to be self-sufficient in dairy products, so why ship stuff in from New Zealand? Britain has a lot of dairy farmers after all and there is nothing wrong with British cheese. If you are willing to countenance the costs, including the environmental costs, the dairy herds of Munster could relocate to the arid plains of Andalucía.

But the argument fails on its own terms. It has been calculated that the efficiencies are such that New Zealand dairy production uses less energy, even with the shipping component, than would the expansion of British dairying into less suitable parts of the country currently devoted to arable crops. In any event, the task of climate policy is not to economise product-by-product on energy inputs, ignoring the scarcity of all the other factors of production. The task is to discourage emissions on a global basis in the manner with the lowest overall economic cost.

That this is not happening is a consequence of the extreme difficulty of securing agreement internationally on a concerted global policy. The best that has been achieved is the solemn adoption of aspirational national emission targets which make no economic sense and to which the commitment of governments is suspect. Concrete measures to discourage emissions are ducked.

An illustration of this, and a tiny excuse for the food miles propaganda, is the unfortunate reality that marine diesel and jet kerosene are not taxed at all, due to international agreements that long pre-date the concerns about climate change. About 10c/l on both would correspond to the kind of optimal carbon tax which would place global policy on a safe trajectory. This would add a few per cent to long-distance freight costs but would not make dairying profitable in the granaries of East Anglia. An efficient carbon tax would need to be accompanied by numerous minimum-tax measures in all other areas and an end to fossil fuel subsidies. The biggest offenders are, by and large, countries outside of Europe.

Marketing gimmicks

It is the failure to face the music on these issues which leaves the door open to the rent-seeking corporate welfare enthusiasts for green energy, and the slick marketing gimmicks in the food business.

Consumers genuinely concerned about climate change would be well advised to resist the current campaigns to buy locally-produced food: there is no guarantee that any useful purpose, environmental or otherwise, is served by encouraging inefficient patterns of international specialisation in agricultural production.