As wind farms show, we must be more sceptical about quack remedies peddled in the name of environmentalism.

An independent study declared at the weekend that most wind farms in England are a waste of space. Government targets for turbines assume that they will operate at 30% of capacity. Most work well below that, because their sites are insufficiently windy.

Businesses which establish turbines beside their offices, not to mention politicians who put them on their houses, are erecting “a garden ornament, not a power station”, in the words of an adviser to the Renewable Energy Foundation, which carried out the study. “These are statements about the company’s corporate social responsibility, not efficient generating capacity.” They are also, of course, damnably ugly.

The study is unsurprising to those of us who have believed all along that turbine mania reflects an unholy alliance between ambitious manufacturers, greedy landowners and credulous ministers - happy to lavish extravagant subsidies on doubtful technology which burnishes their green credentials without costing anybody save the taxpayer, who exists to be stuffed.

Likewise last week, the Economist published an assessment of the Fairtrade scheme, whereby shoppers knowingly pay a premium for food which is organically grown and meets minimum standards of “fair” prices paid to growers. The Economist suggests that Fairtrade merely indulges the almost unlimited gullibility of well-meaning consumers. They do not stop to think that 90% of the premium goes to the retailer, not the producer; that food can be delivered in huge lorries to supermarkets at less energy cost than is incurred by distribution in smaller vehicles to farmers’ markets. It is the car journeys we make to shops which cause food energy costs to soar.

“Buying British” may be patriotic, but makes limited ecological sense. Lamb can be raised in New Zealand and sold in England for less energy-cost than producing it here. Winter tomatoes can be grown in Spain and trucked to British shops more energy-economically than by growing them under glass here.

Questions are raised about the entire organic-growing concept: ploughing land to destroy weeds may do more environmental damage through fuel use than spraying herbicides. Some experts argue that a “no till” growing system, based on sowing cover crops and using herbicides, is more sustainable than so-called organic farming, a doubtful and uncertainly-defined concept even on a good day.

Now, my purpose here is not to claim instant credentials as a pundit on any of these issues, for which I am less qualified than, well - George Monbiot. It is merely to suggest that we, as citizens, should be much more sceptical about quack remedies peddled in the sacred name of environmentalism.

Thoughtful people have reached a condition in which most of us, individually as well as collectively, want to behave better towards the environment than we have done in the past. We yearn to make our tiny contributions towards stemming global warming, and pursuing sustainable resource policies.

Unfortunately, however, it is much harder to do so than we want to think. There are sharks out there, dressed in shiny green camouflage suits, who want to persuade us that by buying this, not buying that, despoiling the landscape with turbines each bearing the Toynbee seal of approval, we can “do our bit” without needing to spend years in the trenches, or go over the top at Passchendaele.

The truth, of course, is that, as with every divorce, there is no painless means of parting from our old life and embracing a new. Almost every significant improvement in the global environment will require international agreements made by governments, together with savage fiscal burdens imposed on individuals to change their behaviour, above all in the use of fossil fuels. Only a tiny minority of people are willing - for instance - to drive less, unless obliged by cost to do so.

It does not seem fanciful to me, a military historian, to compare the current passion for erecting wind turbines with the building of RAF Blenheim bombers in 1939. A few of you may have forgotten that the Blenheim was a disastrous military aircraft, known to be so at the time. Yet it was built in its hundreds, and rushed into deployments which conveyed planes and their hapless pilots almost seamlessly to extinction at the hands of the Luftwaffe.

The rationale for this folly was simple: it was “better to build something than nothing”. In truth, of course, it was pointless to put into the air machines incapable of doing the business, as pilots’ widows agreed. The erection of wind farms in England costs no lives, but represents the same mindset.

Sustainable energy we must have. Some of us pray nightly for the swift evolution of wave-power technology, offshore wind farms, electric cars, improved water harvesting, and home insulation. But it represents expensive, landscape-wrecking madness to plant turbines where there is insufficient wind to render them economic, which means almost everywhere in England.

Likewise on the issue of food: many of us find the words “world trade talks” mind numbing, but it is time to wake up. If we really want to help poor people and the environment, vastly more important than buying doubtfully green products in the supermarket is to end Europe’s common agricultural policy, along with US farm protectionism, and drastically liberalise the poor world’s access to our markets.

Of course this is difficult, and requires commitments by western governments, of a kind which are so far appallingly lacking. But these are indispensable if we are serious about promoting rational global agricultural policies. It also seems evident that we need to know more, quickly, about the environmental economics of shipping agricultural products across the world. Many of us worry about this, while being unsure about facts in an area where they are notoriously hard to come by.

Environmentalism generates extravagant emotion and often unreliable analysis. Some of us have never forgotten Greenpeace’s successful 1998 campaign to prevent the offshore sinking of the redundant Brent Spar oil rig. Subsequent studies suggested that Shell’s proposed solution would have been much greener than Greenpeace’s.

I respect much that Greenpeace does, in particular its crusade against global despoliation of fisheries, but Brent Spar was not an isolated example of the abuse of campaigning sentiment. Likewise, the arguments about nuclear power and GM crops are much more complex than many greens allow. Only a lunatic could embrace either technology with enthusiasm. Yet, as usual, there are important arguments about choices. Some of us believe that both will have to be accepted, because the alternatives are unconvincing.

The best argument for organic food purchases, like hybrid cars, is that at least they enable consumers to make gestures which show that they care. Climate change frightens many of us, including me, more than international terrorism.

It is because so many people are now waving green flags that an aspirant national leader like David Cameron jumps on the bandwagon. However cynical his motives, if more politicians start thinking like him and Al Gore rather than like George W, there is some small hope for us all. But please: unless or until the numbers add up, no more subsidised, futile turbines which look satanic beside the M4 and silly atop houses in Notting Hill.