After six years of denial, the United States now insists that we find ways to block some of the sunlight reaching the earth. This means launching either mirrors or clouds of small particles into the atmosphere. The demand appears in a recent US memo to the Intergovernmental Panel on Climate Change. It describes “modifying solar radiance” as “important insurance” against the threat of climate change.

Every scheme that could give us a chance of preventing runaway climate change should be considered on its merits. But the proposals for building a global parasol don’t have very many. A group of nuclear weapons scientists have proposed launching into the atmosphere a million tonnes of tiny aluminium balloons, filled with hydrogen, every year. Another proposal suggests spraying billions of tonnes of sea-water into the air. Another scheme would inject sulphate particles into the stratosphere. All these fixes appear more expensive than cutting the amount of energy we consume. None reduces the concentration of carbon dioxide, which acidifies the oceans, with grave consequences for the food chain.

The demand that money and research be diverted into these quixotic solutions is another indication that Bush’s avowed conversion to the cause of cutting emissions is illusory. He is drumming up new business for his chums. In his State of the Union address, he spoke of “the serious challenge of global climate change” and announced that he was raising the government’s mandatory target for alternative transport fuels five-fold. This is wonderful news for the grain barons of the red states, who will grow the maize and rapeseed that will be turned into biofuel. It’s a catastrophe for everyone else.

An analysis published last year by the Sarasin Bank found that until a new generation of vegetable fuels, made from straw or wood, is developed, “the present limit for the environmentally and socially responsible use of biofuels is roughly 5 per cent of current petrol and diesel consumption in the EU and US”. Bush now proposes to raise the proportion to 24 per cent by 2017. Already, though the rich world has replaced just a fraction of one per cent of its transport fuels, the UN Food and Agriculture Organisation reports that using crops to feed cars has raised world food prices.

But at least the argument over whether or not manmade climate change is happening is over. On Friday the Intergovernmental Panel on Climate Change publishes the first installment of its vast report. It shows that if you persist in believing that there is no cause for concern, you must have buried your head till only your toes are showing. If Bush now acknowledges that there’s a problem, surely we’ve seen the last of the cranks and charlatans who grabbed so much attention with their claims that global warming wasn’t happening? Some chance. A company called Wag TV is completing a 90-minute documentary called The Great Global Warming Swindle. Manmade climate change, the channel tells us, is “the biggest scam of modern times. The truth is that global warming is a multibillion-dollar worldwide industry: created by fanatically anti-industrial environmentalists; supported by scientists peddling scare stories to chase funding; and propped up by complicit politicians and the media. The fact is that CO2 has no proven link to global temperatures ... solar activity is far more likely to be the culprit.”

The programme’s thesis revolves around the deniers’ favourite canard: that the “hockey-stick graph” showing rising global temperatures is based on a statistical mistake made in a paper by the scientists Michael Mann, Raymond Bradley and Malcolm Hughes.

The decision to commission this programme seems even more odd. In 1997 the director, Martin Durkin, produced a similar series for Channel 4 called Against Nature, which maintained that global warming was a scam dreamed up by environmentalists. More damagingly, the only way in which Durkin could sustain his thesis was to deceive the people he interviewed and edit their answers to change their meaning. After complaints by his interviewees, the Independent Television Commission found that “the views of the four complainants had been distorted.” So the whole weary business of pointing out that the evidence against manmade climate change is sparse and unable to withstand critical scrutiny, while the evidence in favour is overwhelming and repeatedly confirmed, must begin all over again.

How often must scientists remind the media that a handful of studies do not amount to the refutation of an entire discipline? But with Bush’s defection, the quacks making these claims are diminishing fast. Now the oil and coal companies that support such people have changed their target. Instead of trying to persuade us that manmade global warming is a myth, they are seeking to divert us into doing everything except the one thing that has to happen: reducing our consumption of fuel. — The Guardian