What fun it is watching again all those smug Volkswagen ads on YouTube, featuring men in mid-life crisis revving up their Golfs and Passats. German carmakers vie with French farmers for their sacred status in the European Union. That it has taken US authorities to sniff out the company’s cheating on emissions tests doesn’t say much for European environmental law, which is good at telling us we can only have low-powered kettles, but apparently unable to sniff out high emissions from overpowered diesel cars.

But the VW scandal isn’t just a story of corporate turpitude. It is part-product of an environmental policy in Britain as much as across the EU which has become fixated on carbon emissions to the exclusion of virtually everything else. Diesels have grown to account for just under half the UK car market thanks to changes the Blair government made to vehicle excise duty. From 2001, punitive rates of up to £500 were applied to cars which emit carbon emissions of more than 225g/km, while cars below 120 g/km were treated to token road-tax rates. As manufacturers quickly discovered, the only way to get many vehicles below these thresholds was to make them diesel.

It was well known that diesel engines produced large amounts of tiny carcinogenic soot particles, but this was brushed over. Particulate emissions were meant to be dealt with by filters, yet these are known to become blocked if engines spend too much time idling, as they do on urban roads. Diesels also produce far higher levels of nitrogen oxides, the subject of the VW scandal.

But the problem doesn’t end with diesel engines. Take wood-burning. That wood-combustion emits large quantities of soot particles was not lost on the authors of the 1956 Clean Air Act, passed to prevent a repeat of the deadly London smog of four years earlier. Wood fires were banned in smokeless zones along with coal fires. Burning wood also releases nitrogen oxides and carbon monoxide. Yet come the advent of climate change, and emissions from wood-burning have been forgotten. Far from being banished, wood-burning is now actively encouraged through a scheme known as the Renewable Heat Incentive, which lets owners of pellet stoves and boilers claim thousands of pounds of subsidies a year.

Burning biomass pellets made from wood and other vegetable matter is not so polluting as an open wood fire: stoves operate at higher temperatures and combustion is therefore more efficient. But they are hardly ‘clean’ energy. According to one Portuguese study, pellet stoves were found to emit half to two thirds as much soot as wood fires. A study of air pollution in British cities by King’s College London found that wood and pellet stoves account for 13 per cent of particulate pollution in some cities.

On a larger scale, coal-fired power stations have been incentivised to switch to burning wood pellets. The country’s largest coal power station, at Drax in Yorkshire, is gradually converting all its burners to run on wood pellets. The incentives were based on the conceit that burning wood is carbon-neutral, because it releases into the atmosphere only carbon dioxide recently sucked from the air by growing trees. That ignores something important: growing and harvesting trees, as well as manufacturing wood pellets and getting them to a power station, consumes large quantities of fossil fuels.

When the Department for Energy and Climate Change eventually did the calculations, the results were shocking. As Britain consumed 4.6 million tonnes of pellets last year but only produced 0.3 million tonnes from our own forests, the vast bulk must be imported, mostly from North America. For every MWh of electricity generated by burning wood pellets it turned out that between 0.16 MWh and 0.96 MWh of energy was being consumed in making and transporting the pellets. Nearly as much fossil fuel was being consumed as ‘renewable’ energy produced. We might as well have burnt coal and generated electricity from that.

Whether burning pellets reduces carbon emissions depends on what would otherwise happen to the wood from which they were made. If the pellets come from sawdust or fallen trees that would have been burnt by US foresters, it makes sense from the point of view of carbon emissions to burn them for energy. But if the trees would have been allowed to decompose where they fell in a Canadian forest, rotting slowly or turning to peat, it makes no sense at all.

It is an obsession with carbon emissions, too, that has driven policy on biofuels. Again, it makes sense from an environmental point of view to burn agricultural waste to produce energy. It is another matter to produce biofuels on a scale that requires the deforestation of land on which to grow them. Wind turbines, too, have been incentivised with little regard to other environmental problems. It emerged this week that gannet populations off Scotland face decimation from a new offshore windfarm close to their breeding grounds because they fly at a height above that of the lowest tips of the blades.

Then there is nuclear power. Remember the ‘Nuclear power: no thanks’ stickers that were the trademark of greens in the 1970s? The problems of nuclear energy have not gone away. We still have the issue of how to secure nuclear waste which will take thousands of years to decompose. And while nuclear power in Britain has an excellent safety record, no government has explained how we would deal with the economic cost of a serious disaster like the one that struck the Fukushima plant in Japan after the 2011 tsunami. Nuclear power is one thing in remote locations; quite another in highly developed ones. If the same 18-mile exclusion zone had to be set up around Hinkley Point as around Fukushima, we would have to evacuate Bridgewater,Weston-super-Mare, Taunton and several other towns.

Yet the green movement has gone strangely quiet on nuclear power. Anything which reduces carbon emissions they now reckon is good — even if 30 years ago they were trying to tell us nuclear toxicity would give us all cancer. When environmentalism becomes fixated on one thing the loser inevitably turns out to be the environment.