Rarely in political history can there have been such a rapid and dramatic reversal of a received wisdom as we have seen in the past 18 months over biofuels - the cropping of living plants, such as soybeans, wheat and sugar cane, to generate energy.
Two years ago biofuels were still being hailed as a dream solution to what was seen as one of the most urgent problems confronting mankind - our dependence on fossil fuels, which are not only finite but seemed to be threatening the world with the catastrophe of global warming.
In March 2007 the leaders of the European Union, in a package of measures designed to lead the world in the "fight against climate change", committed us by 2020 to deriving 10pc of all transport fuel from "renewables", above all biofuels, which theoretically gave off no more carbon dioxide than was absorbed in their growing.
Since then, however, the biofuels dream has been disintegrating with the speed of a collapsing card house. Environmentalists, formerly keen on this "green energy", expressed horror at the havoc it was inflicting on the world's ecosystems, not least the clearing of rainforests to grow fuel crops.
As the world suddenly faced its worst food shortage for decades, sending prices spiralling, experts pointed out that a major cause had been the diverting of millions of hectares of farmland from food production to fuel.
The damage this was inflicting on the world's poor led a United Nations official to describe the rush for biofuels as "a crime against humanity".
As damaging as anything to the belief that biofuels could help save the planet from global warming have been various studies showing that producing biofuels can give off more carbon dioxide than they save.
So devastating has been this production in the light of the "global food crisis", then, within a matter of weeks, redesignated for biofuel production.
Yet, despite all this going on behind the scenes, when the EU's political leaders nodded through their "global warming" package in March 2007, biofuels were thrown in, seemingly without any questioning from the politicians, including Tony Blair.
In fact, it was at this point that, with startling speed, the backlash against biofuels suddenly erupted on all sides.
Even before the EU had adopted its new target, the first criticism of biofuels was coming from those same environmental groups, Greenpeace and Friends of the Earth, which had once been their most fervent advocates.
Their particular focus was the damage being done in the Third World, not least by the clearing for biofuels of vast areas of rainforest in Brazil and Indonesia, inter alia endangering the survival of Borneo's orang-utans.
Next to weigh in, as the world suddenly woke up to its serious food shortage, were all those experts pointing out that a significant reason for this was the vast area of foodgrowing land already diverted to biofuels, thus shrinking food stocks and driving up prices.
According to the World Bank's top economist, Don Mitchell, biofuels had been responsible for three-quarters of the 140pc rise in world food prices between 2002 and 2008.
It was this that last October prompted Jean Ziegler, the UN's "special rapporteur on the right to food", to comment that biofuels could only bring "more hunger to the poor people of the world" and were a "crime against humanity".
Most alarming of all to the global warming lobby, however, was a succession of studies showing that, far from helping to cut global carbon dioxide emissions, biofuel production can often give off much more carbon dioxide than it saves - even the British Government, which prides itself on being the greenest of the green, commissioned a review, published last Monday, urging a slowdown in the move to biofuels.
When this recommendation was endorsed by senior ministers, this put Britain directly at odds with a European Union policy to which it had already signed up. But the EU is firmly holding its line, saying it has no intention of lowering its target.
* Click here to visit The Age website to read the full in-depth analysis written by Christopher Booker and Richard North, who recently published Scared To Death: From BSE to Global Warming, How Scares Are Costing Us The Earth.